Journal articles: 'Ductile-to brittle transition temperature (dbtt)'

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Lee, Tae-kyung, Seokmin Hong, Jongmin Kim, Min-Chul Kim, and Jae-il Jang. "Evaluation of Transition Temperature in Reactor Pressure Vessel Steels 6using the Fracture Energy Transition Curve from a Small Punch Test." Korean Journal of Metals and Materials 58, no. 8 (August 5, 2020): 522–32. http://dx.doi.org/10.3365/kjmm.2020.58.8.522.

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The small punch (SP) test is one of the small specimen test techniques, and standardization of the SP test method for evaluating the mechanical properties of metallic materials is in progress. In this study, the impact transition temperature of reactor pressure vessel steels (RPV) in nuclear power plants was estimated using the draft standard SP test method. The SP fracture energy (ESP) and normalized SP fracture energy (ENSP) of the RPV steels were evaluated at various temperatures, and their transition curves were derived and compared to the transition curve in the Charpy V notch (CVN) test. The SP transition region appeared at a much lower temperature range than that of the CVN owing to the size and notch effect. Ductile brittle transition temperature (DBTT) in the SP transition curve showed a linear relationship with DBTT and T41J in the CVN transition curve. The ductile to brittle transition behaviors of SP specimens were analyzed using fractographs and compared with the transition curves in ESP and ENSP. ENSP started to decrease at the temperature at which the SP ductile to brittle transition behavior occurred, and this means that the ENSP transition curves were in good agreement with transition behavior in the SP test. However, the ESP transition curves did not match transition behavior. Using DBTT in the ENSP transition curve is appropriate to estimate the CVNDBTT and T41J.

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Hwang, Byoung Chul, Tae Ho Lee, Seong Jun Park, Chang Seok Oh, and Sung Joon Kim. "Ductile-to-Brittle Transition Behavior of High-Nitrogen 18Cr-10Mn-0.35N Austenitic Steels Containing Ni and Cu." Materials Science Forum 654-656 (June 2010): 158–61. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.158.

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Ductile-to-brittle transition behavior of high-nitrogen 18Cr-10Mn-0.35N austenitic steels containing Ni and Cu was investigated by means of Charpy impact test and fractographic analysis. The commonly observed fracture mode of the specimens tested at -196 oC was transgranular cleavage-like brittle with flat facets occurring along {111} crystallographic planes, thereby leading to the occurrence of ductile-to-brittle transition. For all the steels investigated in the present study, the ductile-to-brittle transition temperature (DBTT) measured from Charpy impact tests was much higher by 90 to 135 oC than that predicted by empirical equation strongly depending on N content. The combined addition of Ni and Cu enabled the 18Cr-10Mn-0.35N steels to have the lowest DBTT, which could be explained by relatively high austenite stability and favorable effect of Cu as well as the absence of delta-ferrite.

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Shamim, Shahrukh, Gaurav Sharma, and Chandrabalan Sasikumar. "The Effect of Intermetallic Phases on Ductile to Brittle Transition of Aluminium-Iron Alloy." Applied Mechanics and Materials 592-594 (July 2014): 770–75. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.770.

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The effect of intermetallic phases and grain size on ductile to brittle transition temperature of Aluminium-Iron alloy (Al–11% Fe) was investigated in this research work. An Izod impact testing method was adopted to study the DBTT in the temperature interval of 77 K to 373 K. The ductile-brittle transition points: fracture transition plastic (FTP), fracture-appearance transition temperature (FATT), impact energy transition temperature (IETT), fractional surface area of cleavage (brittle) and fibrous (ductile) fractures and grain size of the samples were also determined. The fracture toughness of Al-Fe alloy found decreasing with temperature in contrast to conventional materials. The fractographic investigation revealed that the microstructural changes play a major role in determining the fracture toughness of these alloys. Annealing of these samples slightly improved the fracture toughness as the spherical morphology of intermetallic particles resists the crack propagation.

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Khattak, M. A., M. A. Khan, and Mohd Nasir Tamin. "Effects of Thermal Aging on Ductile-to-Brittle Transition Temperature Behavior of Welded A516 Steel." Key Engineering Materials 462-463 (January 2011): 1379–84. http://dx.doi.org/10.4028/www.scientific.net/kem.462-463.1379.

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Prolonged high temperature exposure of welded C-Mn steels is likely to cause microstructural changes leading to an inrease in the ductile-to-brittle transition temperature (DBTT) of the welded joint. Consequently, such degrading material properties should be quantified in view of establishing accurate component life prediction model. This study examined effects of isothermal aging on DBTT behavior of the heat affected zone (HAZ) in welded Type A516 Gr 70 steels. Microstructures of the as-received weld region revealed the presence of pearlite and ferrite in the base metal while upper and lower bainite are found in the HAZ and weld metal, respectively. Hardness measures for the weld metal region, HAZ and base steel are 172, 209 and 150, respectively. Aging at 420 oC, 500 hours lowers hardness value of the HAZ by 20 %. A series of Charpy impact tests on V-notched specimens are performed for as-received and thermally aged samples at 420 oC for 500, 800 and 1200 hours. Results showed that the absorbed impact energy displays a sigmoidal variation with test temperatures. DBTT ranges from -60 to 5 oC for HAZ while narrow range from -25 to 12 oC for weld metal region. Absorbed impact energy variations in samples aged for durations up to 800 hours display another saturation level over test temperatures between -30 to 10 oC. Fractographic analysis on HAZ fracture surface indicated brittle fracture at -60 oC while ductile failure dominated at 27.7 oC. A mix-mode fracture mechanism is displayed for test conducted at -38 oC.

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Rieth, Michael, and Andreas Hoffmann. "Impact Bending Tests on Selected Refractory Materials." Advanced Materials Research 59 (December 2008): 101–4. http://dx.doi.org/10.4028/www.scientific.net/amr.59.101.

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The possible use of tungsten alloys as structural materials in future fusion reactor divertors strongly depend on their ductile-to-brittle transition temperature (DBTT). The present paper gives an overview on different rod and plate materials fabricated by PLANSEE. It is demonstrated that DBTT is clearly improved compared to commercially available standard materials. Moreover, the significant impact of the microstructure on fracture mode and on toughness is discussed in detail.

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Takahashi, O., Y. Shibui, P. G. Xu, S. Harjo, T. Suzuki, and Y. Tomota. "Microstructural Features and Ductile-Brittle Transition Behavior in Hot-Rolled Lean Duplex Stainless Steels." Quantum Beam Science 4, no. 1 (March 5, 2020): 16. http://dx.doi.org/10.3390/qubs4010016.

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The characteristics of texture and microstructure of lean duplex stainless steels with low Ni content produced through hot rolling followed by annealing were investigated locally with electron backscatter diffraction and globally with neutron diffraction. Then, the ductile–brittle transition (DBT) behavior was studied by Charpy impact test. It is found that the DBT temperature (DBTT) is strongly affected by the direction of crack propagation, depending on crystallographic texture and microstructural morphology; the DBTT becomes extremely low in the case of fracture accompanying delamination. A high Ni duplex stainless steel examined for comparison, shows a lower DBTT compared with the lean steel in the same crack propagating direction. The obtained results were also discussed through comparing with those of cast duplex stainless steels reported previously (Takahashi et al., Tetsu-to-Hagané, 100(2014), 1150).

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Yuan, Hao, Yue Zhang, Artur V. Ganeev, Jing Tao Wang, and Igor V. Alexandrov. "Strengthening and Toughening Effect on Tungsten Subjected to Multiple ECAP." Materials Science Forum 667-669 (December 2010): 701–6. http://dx.doi.org/10.4028/www.scientific.net/msf.667-669.701.

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This paper presents the research results of the grain refining effect on the ductile-to- brittle transition temperature (DBTT) of commercial purity tungsten. The as-received tungsten was subjected to eight passes of equal-channel angular pressing (ECAP) at decreasing temperatures from 1300 to 1150 °C. According to optical and TEM microscopy the average grain size was refined considerably from ~80 μm to ~1 μm. The mechanical tensile tests, carried out at various temperatures for the tungsten samples, showed that DBTT decreased approximately 80 °C as a result of microstructure refinement by ECAP, at the same time the strength also increased 50-100 % by grain refinement. SEM observation of the fractures confirmed the mechanical testing results.

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Kameda, Jun, and Martin L. Jokl. "Ductile-brittle transition temperature shift controlled by grain boundary decohesion and thermally activated energy in Ni-Cr steels." Corrosion Reviews 37, no. 5 (September 25, 2019): 455–58. http://dx.doi.org/10.1515/corrrev-2019-0052.

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AbstractTemper embrittlement induced by segregation of metalloid solutes to grain boundary (GB) was evaluated by a shift of the ductile-brittle transition temperature (DBTT). DBTT was found to be linearly correlated with the amount of metalloid on the GB (Xgb) for both dynamic and static displacement rates (dδ/dt) in high and medium hardness steels. Recent first-principles calculations have determined the GB embrittling potency (Δep) of segregated Sb, Sn and P. In both high and medium hardness steels, the slope (α) of DBTT vs. Xgb was found to be linearly dependent on Δep regardless of the segregated solutes. In high hardness steels, the slope is independent of dδ/dt, while in medium hardness steels the α is dependent on dδ/dt. An Arrhenius plot of dδ/dt vs. the reciprocal DBTT was used to drive the thermal activation energy (Eact), which represents a barrier to plasticity. It was found that Eact correlates to a reduction in the GB fracture surface energy. The Eact depends strongly on GB decohesion in high hardness steels but only weakly depends on it in medium hardness steels.

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Lee, Won Bae, Jeong Kil Kim, Joon Sik Park, In Su Woo, and Jong Bong Lee. "Effect of Interstitial Elements on the Toughness of Ferritic Stainless Steel Weld." Materials Science Forum 580-582 (June 2008): 45–48. http://dx.doi.org/10.4028/www.scientific.net/msf.580-582.45.

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In this study, the toughness of 11Cr ferritic stainless steel weld was evaluated by DBTT (Ductile-Brittle-Transition-Temperature) with the interstitial elements level. DBTT of the weld increased with increasing interstitial level due to the formation of martensite phase and solidsolution strengthening. Interstitial elements level should be limited by the adoption of back shielding gas during welding process because increased C+N level detrimentally affects the toughness of ferritic stainless weld. Adoption of Ar as back shielding gas lowered N content in the weld.

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Zhang, Zu Rui, Hua Bing Li, Zhou Hua Jiang, and Zhen Li. "Microstructural and Mechanical Aspects of High Nitrogen Steels at Cryogenic Temperature." Advanced Materials Research 97-101 (March 2010): 733–36. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.733.

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Charpy V-Notch impact tests of N1, N2 and N3 steels from 77K to 293K are possessed in this paper. With increasing the nitrogen concentration, the ductile to brittle transition temperature (DBTT) increases. The toughness of the tested steels decreases rapidly with decreasing the temperature. The change of fracture patterns of high nitrogen austenitic stainless steels is dimple → shallow dimple → mixture of quasi-cleavage facet and dimple → cleavage facet. Fracture facets with river patterns, with tear ridges, along annealing twin boundary and cross the annealing twin plane are observed in this investigation. Critical dislocation density of crack tips ρc=[6π(τp)2/(KIc)2]2 can affect ductile to brittle transition (DBT) behavior at cryogenic temperature. Deformation twinning is also frequently observed at cryogenic temperature. Crack forms along the coherent twin boundary between one twin and the matrix.

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Pan, Jianhua, Yan Wang, and Mingjie Guo. "Performance of ferritic steel 16MnDR using improved local fracture criterion." E3S Web of Conferences 260 (2021): 03023. http://dx.doi.org/10.1051/e3sconf/202126003023.

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Based on the finite element analysis and fracture toughness test data, this paper verifies the improved Ritchie-Knott-Rice (RKR) local failure criterion using 16MnDR ferritic steel for cryogenic pressure vessels. This criterion's applicability to 16MnDR was verified to verify fracture toughness's different influence factors in the ductile-to-brittle transition temperature (DBTT) region, such as specimen thickness (TST) and temperature. The results indicate that the (4δt, σ22c) criterion applies to 16MnDR steel and effectively transfers the minimum Jc value between samples of different temperatures and thickness.

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12

Wolfenden, A., Y.-H. Joo, T. Hashida, and H. Takahashi. "Determination of Ductile-Brittle Transition Temperature (DBTT) in Dynamic Small Punch Test." Journal of Testing and Evaluation 20, no. 1 (1992): 6. http://dx.doi.org/10.1520/jte11891j.

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Kim, Hyung Ick, Yong Huh, Jae Sil Park, and Chang Sung Seok. "Evaluation of the Ductile-Brittle Transition Behaviour of Aging Specimens by the Fracture Toughness Test." Key Engineering Materials 321-323 (October 2006): 536–40. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.536.

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The safety and reliability of industrial machineries and structures used in various, and severe conditions has become an increasing concern. This study proposes ductile-brittle transition temperature (DBTT) evaluation technique by the sub-sized specimen test to prevent cleavage fracture. Four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared. The fracture toughness tests were performed on sub-sized specimens both at room and low temperatures. The results of the fracture toughness tests were analyzed to obtain the DBT behaviours of the specimen materials

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Bai, Bing, Chang Yi Zhang, Jia Sheng Wang, Zhen Feng Tong, Qun Xian Lv, and Wen Yang. "Thermal Aging Effect of 17-4PH Martensitic Stainless Steel Valves for Nuclear Power Plant." Materials Science Forum 850 (March 2016): 96–100. http://dx.doi.org/10.4028/www.scientific.net/msf.850.96.

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In this work, impact toughness and tensile properties of valve stem used in NPP are obtained. Combining with microstructure analysis of fracture morphology and metallurgical structure, the thermal aging behavior of the martensitic stainless steel is studied. The results show that the thermal aging embrittlement is significant when the valve stem serves in high temperature for a long time. The ductile to brittle transition temperature (DBTT) and the hardness increase, and the upper platform energy decreases.

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Lee, S., J. Wadsworth, and O. D. Sherby. "Impact Properties of a Laminated Composite Based on Ultrahigh Carbon Steel and a Ni-Si-Steel." Journal of Engineering Materials and Technology 114, no. 3 (July 1, 1992): 278–81. http://dx.doi.org/10.1115/1.2904173.

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A laminated composite consisting of an ultrahigh carbon steel (UHCS) and an 8Ni-2Si iron interleaf material can be selectively heat treated without carbon diffusion between adjacent layers. This desirable attribute leads to a low ductile-brittle transition temperature (DBTT) of about 163K ( − 110°C) after selective heat treatment. This result is a consequence of notch blunting from the presence of the sharp interlayer boundary and the tough interleaf material. Based on Charpy notch impact results of selectively heat-treated UHCS composites containing 8Ni-2Si iron and other interleaf materials, it is concluded that the DBTT is principally a function of the notch-toughness of the interleaf material.

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Gunawan, Gunawan, and Amir Arifin. "INTERGRANULAR CORROSION AND DUCTILE-BRITTLE TRANSITION BEHAVIOUR IN MARTENSITIC STAINLESS STEEL." Indonesian Journal of Engineering and Science 2, no. 3 (September 8, 2021): 031–41. http://dx.doi.org/10.51630/ijes.v2i3.23.

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Material mechanical behavior is critical for both safety and economic considerations. Because engineering items are manufactured using appropriate grade materials, mechanical approval of the materials used must be completed before assembly. Petrochemicals, marine, and biomaterials are just a few of the industries that use stainless steel. Despite its extensive use, structural failure is still frequently caused by inadequate stainless steel type selection. As a result, dangerous conditions, resulting in personal harm or financial loss. Dangerous conditions is might result in accidents, resulting in personal injury or financial loss. Martensite stainless steel is a type of stainless steel with a high strength value but is brittle, necessitating careful handling. Intergranular corrosion, sensitization, tempering heat treatment, and the Ductile to Brittle Transition Temperature (DBTT) are topics still working on Martensite stainless steel for researchers.

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Jeon, Ji Ho, Woo Il Lee, Jong Min Choi, and Sung Woong Choi. "Analysis of Cryogenic Impact Properties for a Glass-Fiber-Reinforced Dicyclopentadiene with a Different Amount of Decelerator Solution." Materials 12, no. 19 (October 4, 2019): 3246. http://dx.doi.org/10.3390/ma12193246.

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Composites using dicyclopentadiene (DCPD) as a matrix have gained significant popularity owing to their excellent impact and chemical corrosion resistance. In the present study, experiments addressing the impact behavior of glass-fiber-reinforced DCPD were conducted to quantitatively evaluate its impact properties. The glass-fiber-reinforced polydicyclopentadiene composite utilized in impact tests was manufactured using structural reaction injection molding (S-RIM) because of its fast curing characteristics and low viscosity. The impact properties of the glass-fiber-reinforced DCPD (GF/DCPD) were quantitatively evaluated by varying its fiber content and decelerator solution. The impact properties of neat DCPD and GF/DCPD composites were examined with different amounts of decelerator solution under various temperatures from room temperature to cryogenic temperature to observe the ductile-to-brittle transition temperature (DBTT). With an increase in the fiber weight fraction of the GF/DCPD composite, the effect of the DBTT significantly decreased. However, the decreasing rate retarded as the weight fraction of the GF increased. The decreased DBTT with the addition of GF in the GF/DCPD can be attributed to the differences in the thermal expansion ratio and the interfacial force between neat DCPD and the fiber. A fractograph analysis demonstrates that the effect of the brittle (smooth) surface resulted in a lower impact absorbed energy when the temperature decreased, along with the increased amount of the decelerator.

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Vértesy, Gábor, Antal Gasparics, Inge Uytdenhouwen, Ildikó Szenthe, Ferenc Gillemot, and Rachid Chaouadi. "Nondestructive Investigation of Neutron Irradiation Generated Structural Changes of Reactor Steel Material by Magnetic Hysteresis Method." Metals 10, no. 5 (May 15, 2020): 642. http://dx.doi.org/10.3390/met10050642.

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The neutron irradiation embrittlement of four different types of nuclear pressure vessel materials (three base metals and one weld material) were investigated by a magnetic nondestructive testing method, magnetic adaptive testing (MAT). The method is based on the measurement of minor magnetic hysteresis loops on Charpy specimens irradiated by neutrons in the BR2 reactor. Due to the neutron irradiation, the structure of the material was modified. The Charpy impact method is suitable for destructive characterization of material embrittlement. The results of Charpy impact test measurements at SCK CEN Belgian Nuclear Research Centre were compared with the nondestructively measured magnetic parameters. A definite correlation was found between magnetic descriptors and the ductile-to-brittle transition temperature (DBTT), regardless of the type of material or irradiation condition. The results suggest that this “calibration curve“ can be used to estimate the DBTT from non-destructive measurements.

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Takahashi, Satoru, Masayuki Yoshiba, Raito Kawamura, and Yoshio Harada. "In Situ Observation of Failure Behavior for Plasma Sprayed Thermal Barrier Coating Systems under Static Loadings." Materials Science Forum 522-523 (August 2006): 345–52. http://dx.doi.org/10.4028/www.scientific.net/msf.522-523.345.

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In situ observation of the mechanical failure behavior was conducted for different kinds of the plasma sprayed thermal barrier coating (TBC) systems by means of an optical microscopy under the static loadings at room and elevated temperatures; as the fundamental aspect, in order to clarify the thermomechanical failure mechanism of TBC system in connection with various coating characteristics. Mechanical tensile or compressive loading was applied progressively to the TBC specimen by an axial loading mode. It was found that the failure behavior of TBC system depends strongly on the testing temperature under both the tensile and compressive loadings. At the elevated temperature which is higher than the ductile-brittle transition temperature (DBTT) of metallic bond-coat (BC), in particular, the ceramic top-coat (TC) spallation can be prevented by virtue of the stress relief induced by the enhanced plastic flow in the BC layer. At the room temperature which is lower than the DBTT of BC, on the contrary, the TC spalling was inevitably induced, but the initiation site of TC spalling is closely related with the magnitude of local plastic deformation in the alloy substrate. Furthermore, an influence of thermally grown oxides (TGO) layer developed at the TC / BC interface on the crack initiation and propagation behavior was investigated in some detail.

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Jafari, Meysam, Yuuji Kimura, and Kaneaki Tsuzaki. "Role of Delamination Fracture for Enhanced Impact Toughness in 0.05 %P Doped High Strength Steel with Ultrafine Elongated Grain Structure." Advanced Materials Research 409 (November 2011): 231–36. http://dx.doi.org/10.4028/www.scientific.net/amr.409.231.

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Ultrafine elongated grain (UFEG) structures with strong <110>// rolling direction (RD) fiber deformation texture were produced by warm caliber-rolling at 773 K, namely tempforming in the 1200 MPa-class medium-carbon low-alloy steel with phosphorous (P) contents of 0.001 and 0.053 mass%. Charpy impact tests were performed at temperature range of-196 to 150 °C on the UFEG structure. Regardless of P content, high upper shelf energy about 145 J and a very low ductile to brittle transition temperature (DBTT) of around-175 °C were obtained. P segregation embrittlement completely disappeared in the 0.053 %P steel and both steels showed ductile fracture on the planes normal to RD at temperature range of-150 to 150 °C. The main reason for the high upper shelf energy and very low DBTT in the 0.053 %P steel would be delamination fracture along RD when both 0.001 and 0.053 %P steels showed quite similar microstructures including texture. Since the occurrence of delamination requires relatively weak interfaces or planes, P segregated to the ferrite grain boundaries and interfaces of cementite particles-ferrite matrix and made them feasible paths for crack branching and consequently delamination occurred. We showed in this work the advantage of delamination (crack arrester-type) on the high absorbed energy obtained by 0.053 %P steel in comparison with 0.001 %P steel.

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Alam, Md Zafir, D. Chatterjee, S. V. Kamat, V. Jayaram, and D. K. Das. "Evaluation of ductile–brittle transition temperature (DBTT) of aluminide bond coats by micro-tensile test method." Materials Science and Engineering: A 527, no. 26 (October 2010): 7147–50. http://dx.doi.org/10.1016/j.msea.2010.07.059.

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Mazuro, Paweł, Julia Pieńkowska, and Ewa Rostek. "Influence of Various Heat Treatments on Hardness and Impact Strength of Uddeholm Balder: Cr-Mo-V-Ni Novel Steel Used for Engine Construction." Materials 14, no. 17 (August 30, 2021): 4943. http://dx.doi.org/10.3390/ma14174943.

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The construction of an engine requires optimized geometry and superb material properties in various environments. Tensile and yield strength are not the only parameters essential to consider. Hardness, impact toughness, and ductile-brittle transition temperature (DBTT) are also crucial. In this paper, Balder, Chromium-Molybdenum-Vanadium-Nickel steel with low impact toughness attested is considered. It contains both high Nickel and high Vanadium content, a rare combination among iron-based alloys. This study aims at proving that conventional heat treatment can improve its impact toughness while maintaining hardness level, exceeding its to-date performance. Steel’s exact elemental composition was checked, and material samples’ hardness and impact toughness were measured. Four heat treatments were proposed, then hardness and impact toughness were measured again. It was established that impact toughness over three times higher than marketed (57.3 J against 17 J) can be achieved with simultaneous 2 HRC points (from 46.4 HRC to 48.4 HRC) rise in hardness. Achieved parameters place examined alloy at the high-ranking position among similar steels. Occurrence of temper embrittlement was avoided. Notably, the ductile-brittle transition was not observed in any sample.

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Heilmaier, Martin, Manja Krüger, and Holger Saage. "Recent Advances in the Development of Mechanically Alloyed Mo Silicide Alloys." Materials Science Forum 633-634 (November 2009): 549–58. http://dx.doi.org/10.4028/www.scientific.net/msf.633-634.549.

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We review the current development status of Mo-Si-B alloys consisting of Mo solid solution and the intermetallic phases Mo3Si and Mo5SiB2 which could take advantage of the beneficial oxidation resistance of the silicide phases and of the outstanding mechanical properties of molybdenum. For adequate low temperature toughness a continuous Mo solid solution matrix should be established in the microstructure. Besides, wrought processing of such alloys at elevated temperatures requires the presence of an ultra-fine grained (UFG) microstructure. Both the prerequisites can be fulfilled using mechanical alloying (MA) as the crucial processing step which even yields nanostructured supersaturated powders after milling. However, values for the ductile-to-brittle transition temperature (DBTT) close to room temperature are unlikely due to grain boundary embrittlement by Si segregation. The possibility of reducing this segregation tendency by various micro-alloying additions will be demonstrated. Finally, the high temperature deformation behaviour of these UFG materials will be comparatively assessed against state-of-the-art Nickelbase single-crystalline superalloys.

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Li, Xiucheng, Jingxiao Zhao, Lili Dong, R. Devesh Kumar Misra, Xuemin Wang, Xuelin Wang, and Chengjia Shang. "The Significance of Coherent Transformation on Grain Refinement and Consequent Enhancement in Toughness." Materials 13, no. 22 (November 12, 2020): 5095. http://dx.doi.org/10.3390/ma13225095.

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Coherent transformation is considered to be an effective approach to refine the microstructure and enhance toughness of structural steels. However, there are gaps in the knowledge on the key aspects of microstructure that govern toughness. In this regard, a low alloyed experimental steel with lean chemistry was subjected to a simple heat treatment involving austenitization at different temperatures, followed by quenching and tempering to obtain bainitic microstructures with different boundary composition. The microstructure of the four experimental steels was characterized by electron backscattered diffraction and mechanical properties were determined. The study indicated that the density of high angle grain boundaries does not adequately reflect the change of ductile-to-brittle transition temperatures (DBTT) of the experimental steels. Thus, we propose here a new mechanism on reducing DBTT from the perspective of misorientation of boundary, which takes into consideration these aspects in defining DBTT. One is inhibition effect on cleavage fracture by boundaries with high {100}-plane misorientation angles, and the other is ductility improvement by boundaries with high {110}-plane misorientation angles. Furthermore, the contribution of prior austenite grain boundary, packet boundary, block boundary, and sub-block boundary on toughness is also analyzed.

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Takashima, Yasuhito, Mitsuru Ohata, and Fumiyoshi Minami. "Analysis of Statistical Scatter in Charpy Impact Toughness." Materials Science Forum 783-786 (May 2014): 2394–99. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2394.

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Charpy impact toughness values show large statistical scatter, particularly in the ductile-to-brittle transition temperature (DBTT) range. Although the statistical distribution of Charpy absorbed energy has not been clarified, critical values of the stress intensity factor, J-integral and crack-tip opening displacement (CTOD) at brittle fracture generally show the Weibull distribution with two or three parameters. This study proposes a brittle fracture model, based on the weakest link theory, for evaluating the scatter in Charpy absorbed energy KV. The numerical results show that the amplitude of the opening stress fields ahead of the V-notch at varying amounts of KV are uniquely characterized as the square of the applied load. With these numerical results, the Weibull shape parameter of the statistical distribution of KV is almost equal to 2. The proposed statistical model is verified through experimental results. It is found that the statistical distribution of KV is characterized by a two-parameter Weibull distribution with the shape parameter of 2 under the condition of pure brittle fracture.

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Lindgren, Kristina, Krystyna Stiller, Pål Efsing, and Mattias Thuvander. "On the Analysis of Clustering in an Irradiated Low Alloy Reactor Pressure Vessel Steel Weld." Microscopy and Microanalysis 23, no. 2 (March 21, 2017): 376–84. http://dx.doi.org/10.1017/s1431927617000162.

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AbstractRadiation induced clustering affects the mechanical properties, that is the ductile to brittle transition temperature (DBTT), of reactor pressure vessel (RPV) steel of nuclear power plants. The combination of low Cu and high Ni used in some RPV welds is known to further enhance the DBTT shift during long time operation. In this study, RPV weld samples containing 0.04 at% Cu and 1.6 at% Ni were irradiated to 2.0 and 6.4×1023 n/m2 in the Halden test reactor. Atom probe tomography (APT) was applied to study clustering of Ni, Mn, Si, and Cu. As the clusters are in the nanometer-range, APT is a very suitable technique for this type of study. From APT analyses information about size distribution, number density, and composition of the clusters can be obtained. However, the quantification of these attributes is not trivial. The maximum separation method (MSM) has been used to characterize the clusters and a detailed study about the influence of the choice of MSM cluster parameters, primarily on the cluster number density, has been undertaken.

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Guo, Fujian, Wenle Liu, Xuelin Wang, R. D. K. Misra, and Chengjia Shang. "Controlling Variability in Mechanical Properties of Plates by Reducing Centerline Segregation to Meet Strain-Based Design of Pipeline Steel." Metals 9, no. 7 (July 4, 2019): 749. http://dx.doi.org/10.3390/met9070749.

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Low variability in mechanical properties is required for pipeline project designs to meet a strain-based design, which is used in regions of large ground movements. The objective of this study is to elucidate the influence of centerline segregation in continuously cast slab on variability in the mechanical property of pipeline steel, and controlling centerline segregation can meet the requirements of a strain-based design. Mannesmann rating method was used to evaluate the degree of segregation of two slabs and its effect on variability in mechanical properties of corresponding plates. Microstructural characterization indicated that bainite/martensite was formed in a segregated area where the content of C and Mn enriched. The mechanical property results indicated that controlling the degree of centerline segregation can reduce tensile strength variability and improve ductile-brittle transition temperature (DBTT).

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Xing, Rui Si, Xu Chen, and Dun Ji Yu. "Evolution of Impact Properties of 16MND5 Forgings for Nuclear Reactor Pressure Vessel during Thermal Aging at 500°C." Key Engineering Materials 795 (March 2019): 54–59. http://dx.doi.org/10.4028/www.scientific.net/kem.795.54.

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Effects of thermal aging on tensile and Charpy impact properties in 16MND5 steel was investigated, which were aged at 500°C for 0 h, 1000 h, 3000 h, 5000 h. A significant decrease in the yield stress and ultimate tensile strength was observed after thermal aging, while the elongation exhibited a slight decrease follow by an increase aged for 5000 h. What's more, the ductile-to-brittle transition temperature (DBTT) showed a remarkable increase with the prolongation of thermal aging duration. These facts indicate thermal aging caused embrittlement of the steel, which was further investigated by microstructure observation of SEM. The results show cleavage fracture after thermal aging. Furthermore, experimental results at 350°C thermal aging temperature originated from the previous literature were used to analysis the effect of thermal aging temperature. Thus, thermal embrittlement should be taken seriously.

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Ghaith, Fadi A. "Nonlinear Finite Element Modeling of Charpy Impact Test." Advanced Materials Research 83-86 (December 2009): 182–89. http://dx.doi.org/10.4028/www.scientific.net/amr.83-86.182.

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Finite element modeling of Charpy impact test was performed for a normalized carbon steel specimen based on plane strain geometry and bilinear isotropic hardening plasticity. As the suggested approach takes into account all aspects of nonlinearity such as geometric, material and contact nonlinearities, it may describe the conventional destructive impact test accurately with much less effort and cost. A failure criterion is assumed to be at 10 % of plastic strain based on the tensile experiment data. Impact energy was estimated at different testing temperatures. It was found that impact energy required for fracture of the selected steel specimen at room temperature (i.e. 25 °C) is to be 65.9 Joul. According to simulation results, it is found that the ductile to brittle transition temperature (DBTT) equals 0 °C. In order to validate the numerical model, a comparison study was established by comparing the numerical results with the corresponding experimental tests at the same conditions, which shows good match with maximum deviation of 5 % for all computer runs.

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Kim, Byung Jun, Ryuta Kasada, and Akihiko Kimura. "Effects of Chemical Composition on the Impact Properties of A533B Steels." Materials Science Forum 654-656 (June 2010): 2895–98. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.2895.

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In order to estimate the long life integrity of vessel steels with considering various material compositions and irradiation conditions, it is necessary to understand physical mechanisms of the degradation of mechanical properties. In this research, chemical composition effects were investigated for Reactor Pressure Vessel Steels (RPVS) to apply small specimen test technique to surveillance test method. All specimens used in this study were machined from the A533B plate material, which are standard, low Mn, high Cu, high P, and high Cu and high P steels. Tensile strength is increased by phosphorous and copper additions. Charpy tests were carried out at temperature from 73 K to 473 K. The ductile to brittle transition temperature (DBTT) is shifted to higher temperatures with phosphorus additions accompanied by the reduction of the upper shelf energy (USE). The fracture mode of P-added A533B steels at temperatures in the lower shelf energy (LSE) region is intergranular cracking. Test results were discussed in view of the differences on elements of Cu, Mn and P.

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Sindelar, Robert L., Poh-Sang Lam, George R. Caskey,, and Leta Y. Woo. "Flaw Stability in Mild Steel Tanks in the Upper-Shelf Ductile Range—Part I: Mechanical Properties." Journal of Pressure Vessel Technology 122, no. 2 (November 2, 1999): 162–68. http://dx.doi.org/10.1115/1.556173.

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Mechanical properties of 1950’s vintage, A285 Grade B carbon steels have been compiled for elastic-plastic fracture mechanics analysis of storage tanks (Lam and Sindelar, 2000). The properties are from standard Charpy V-notch (CVN), 0.4T planform compact tension (C(T)), and tensile (T) specimens machined from archival steel from large water piping. The piping and storage tanks were constructed in the 1950s from semi-killed, hot-rolled carbon steel plate specified as A285 Grade B. Evaluation of potential aging mechanisms at both service conditions shows no loss in fracture resistance of the steel in either case. Site and literature data show that the A285, Grade B steel, at and above approximately 70°F (21°C), is in the upper transition to upper shelf region for absorbed energy and is not subject to cleavage cracking or a brittle fracture mode. Furthermore, the tank sidewalls are 1/2 or 5/8-in. (12.7 or 15.875 mm) thick, and therefore, the J-resistance JR curve that characterizes material resistance to stable crack extension under elastic-plastic deformation best defines the material fracture toughness. The JR, curves for several heats of A285, Grade B steel tested at 40°F (4.4°C), a temperature near the average ductile-to-brittle (DBTT) transition temperature (CVN at 15 ft-lb or 20.3 J), are presented. This data is applicable to evaluate flaw stability of the storage tanks that are operated above 70°F (21°C) since, even at 40°F (4.4°C), crack advance is observed to proceed by ductile tearing. [S0094-9930(00)00402-9]

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Zhou, Tihe, Ronald O’Malley, Hatem Zurob, Mani Subramanian, Sang-Hyun Cho, and Peng Zhang. "Control of Upstream Austenite Grain Coarsening during the Thin-Slab Cast Direct-Rolling (TSCDR) Process." Metals 9, no. 2 (February 1, 2019): 158. http://dx.doi.org/10.3390/met9020158.

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Thin-slab cast direct-rolling (TSCDR) has become a major process for flat-rolled production. However, the elimination of slab reheating and limited number of thermomechanical deformation passes leave fewer opportunities for austenite grain refinement, resulting in some large grains persisting in the final microstructure. In order to achieve excellent ductile to brittle transition temperature (DBTT) and drop weight tear test (DWTT) properties in thicker gauge high-strength low-alloy products, it is necessary to control austenite grain coarsening prior to the onset of thermomechanical processing. This contribution proposes a suite of methods to refine the austenite grain from both theoretical and practical perspectives, including: increasing cooling rate during casting, liquid core reduction, increasing austenite nucleation sites during the delta-ferrite to austenite phase transformation, controlling holding furnace temperature and time to avoid austenite coarsening, and producing a new alloy with two-phase pinning to arrest grain coarsening. These methodologies can not only refine austenite grain size in the slab center, but also improve the slab homogeneity.

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Chang, S. J. "Probability of Fracture and Life Extension Estimate of the High-Flux Isotope Reactor Vessel." Journal of Pressure Vessel Technology 120, no. 3 (August 1, 1998): 290–96. http://dx.doi.org/10.1115/1.2842060.

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The state of the vessel steel embrittlement as a result of neutron irradiation can be measured by its increase in ductile-brittle transition temperature (DBTT) for fracture, often denoted by RTNDT for carbon steel. This transition temperature can be calibrated by the drop-weight test and, sometimes, by the Charpy impact test. The life extension for the high-flux isotope reactor (HFIR) vessel is calculated by using the method of fracture mechanics that is incorporated with the effect of the DBTT change. The failure probability of the HFIR vessel is limited as the life of the vessel by the reactor core melt probability of 10−4. The operating safety of the reactor is ensured by periodic hydrostatic pressure test (hydrotest). The hydrotest is performed in order to determine a safe vessel static pressure. The fracture probability as a result of the hydrostatic pressure test is calculated and is used to determine the life of the vessel. Failure to perform hydrotest imposes the limit on the life of the vessel. The conventional method of fracture probability calculations such as that used by the NRC-sponsored PRAISE CODE and the FAVOR CODE developed in this Laboratory are based on the Monte Carlo simulation. Heavy computations are required. An alternative method of fracture probability calculation by direct probability integration is developed in this paper. The present approach offers simple and expedient ways to obtain numerical results without losing any generality. This approach provides a clear analytical expression on the physical random variables to be integrated, yet requires much less computation time. In this paper, numerical results on 1) the probability of vessel fracture, 2) the hydrotest time interval, and 3) the hydrotest pressure as a result of the DBTT increase are obtained. Limiting the probabilities of the vessel fracture as a result of hydrotest to 10−4 implies that the reactor vessel life can be extended up to 50 EFPY (100 MW) with the minimum vessel operating temperature equal to 85°F.

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Al Jabr, Haytham M., John G. Speer, David K. Matlock, Peng Zhang, and Sang Hyun Cho. "Anisotropy of Mechanical Properties of API-X70 Spiral Welded Pipe Steels." Materials Science Forum 753 (March 2013): 538–41. http://dx.doi.org/10.4028/www.scientific.net/msf.753.538.

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The effects of microstructure and texture on the toughness anisotropy of two API-X70 pipeline steels were investigated. One steel contained no nickel (0Ni) and the other contained 0.3 wt pct nickel (0.3Ni). Charpy V-notch impact testing was conducted on plate samples for both steels in three directions: longitudinal (L), transverse (T), and diagonal (D) with respect to the rolling direction. The microstructures of both steels were mixed and consisted of acicular ferrite, granular bainite, and small amounts of polygonal ferrite, with martensite-austenite and retained austenite islands as secondary phases. The ductile to brittle transition temperatures (DBTT) for the Charpy impact test were higher in the D direction for both plates, with a pronounced increase in the 0Ni steel. The anisotropy in toughness was mainly attributed to the crystallographic texture.

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Kennett, Shane C., and Kip O. Findley. "Strengthening and Toughening Mechanisms in Martensitic Steel." Advanced Materials Research 922 (May 2014): 350–55. http://dx.doi.org/10.4028/www.scientific.net/amr.922.350.

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Low carbon martensitic steels are often produced by reaustenitizing and quenching (RA/Q). Direct quenching (DQ) has gained interest in the past few decades and requires quenching immediately after working above or below the austenite recrystallization temperature to form martensitic microstructures. In the current study, microalloyed ASTM A514 steel is used to produce martensite from either equiaxed or pancaked prior austenite grain (PAG) microstructures. The equiaxed PAG conditions simulate microstructures produced by RA/Q and the pancaked PAG conditions simulate microstructures produced by controlled rolling (CR) before DQ. Controlled rolling followed by DQ was simulated with double hit compression in a Gleeble® 3500. The prior austenite grain size (PAGS) was varied between 9 and 75 μm prior to controlled rolling. The strengthening and toughening mechanisms are being investigated in the as-quenched (AsQ), low temperature tempered (LTT: 200 °C), and high temperature tempered (HTT: 600 °C) conditions. The equiaxed PAG condition has a Hall-Petch (H-P) relationship between yield strength (or microhardness) and PAGS in the AsQ condition. There is not a H-P relationship between PAGS and microhardness in the CR-DQ conditions. The CR-DQ conditions generally exhibit higher microhardness than the RA/Q conditions with similar PAGS, with the most significant differences in the larger PAGS conditions. Toughness was only measured in the equiaxed PAG conditions. The smallest PAGS has the lowest ductile-to-brittle transition temperature (DBTT) with the highest strength in the AsQ and LTT conditions. The smallest PAGS has the lowest DBTT and the lowest strength in the HTT condition.

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Guo, Fujian, Xuelin Wang, Jingliang Wang, R. D. K. Misra, and Chengjia Shang. "The Significance of Central Segregation of Continuously Cast Billet on Banded Microstructure and Mechanical Properties of Section Steel." Metals 10, no. 1 (January 2, 2020): 76. http://dx.doi.org/10.3390/met10010076.

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The solidification structure and segregation of continuously cast billets produced by different continuous casting processes are investigated to elucidate their effect on segregated bands in hot-rolled section steel. It suggested that segregated spots are mainly observed in the equiaxed crystal zone of a billet. The solidification structure is directly related to superheating and the intensities of secondary cooling. To a certain extent, the ratio of the columnar crystal increases with the increase of superheating and secondary cooling. Moreover, the number of spot segregations decreases with the decrease of the equiaxed crystal ratio. After hot rolling, the segregation spots are deformed to form segregated bands in steels. The severe segregation of Mn in segregated bands corresponds with that in the segregation spots. The elongation ratio and low temperature toughness deteriorate significantly by a high fraction of degenerate pearlite caused by central segregation. With a decrease of central segregation, the total elongation is increased by 10% and the ductile–brittle transition temperature (DBTT) is also reduced from −10 to −40 °C. According to the experimental results, columnar crystal in billets is preferred to effectively reduce the degree of central segregation and further improve low temperature toughness and the elongation ratio.

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Perlado, J. M., and J. Sanz. "Neutron damage and activation of the first wall of inertial confinement fusion reactors: Recycling and waste disposal." Laser and Particle Beams 11, no. 2 (June 1993): 437–42. http://dx.doi.org/10.1017/s0263034600005024.

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Even though general conclusions cannot be derived for all the protection schemes in inertial confinement fusion (ICF) reactors, the feasibility of the ferritic alloy HT-9 as the main component of the first structural wall (FSW) in ICF facilities using thin-film Li17Pb83 liquid protection, flowing through porous tubes (INPORT), can be demonstrated as a solution in terms of radiation damage. Swelling and shift in the ductile-brittle transition temperature (DBTT) can be analyzed using the results of experimental fast-fission reactors, which are demonstrated to be good experimental tools in that ICF range. The good performance of HT-9 is remarkable. The generation of new solid transmutants and the depletion of initial constituents need also be considered. Further, a reduced-activation HT-9 (niobium-free) has been studied using recycling and shallow land burial (SLB) criteria. The recycling using that HT-9 is shown to be not feasible, as is SLB waste disposal. The unexpected critical role of some short-lived isotopes is remarkable, and more research on their nuclear data must be performed.

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di Schino, Andrea, and Mauro Guagnelli. "Metallurgical Design of High Strength/High Toughness Steels." Materials Science Forum 706-709 (January 2012): 2084–89. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.2084.

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The proper balance between yield strength, YS, and ductile to brittle transition temperature, DBTT, has been the main concern during development of high strength engineering steels and the effect of microstructure on impact toughness has attracted a great attention during the last decades. In this paper a review concerning the relationship between strength and toughness in steels will be presented and the effect of different microstructural parameters will be discussed, aiming toimprovesuch properties in designingnewhigh strength steels. Complex microstructures, obtained by quenching and tempering (Q&T) and thermo-mechanical (TM) processing are considered. The steels are low/medium carbon steels (C=0.04%-0.40%) with yield strength in the range YS=500-1000 MPa. Results show that the strength and the impact toughness behaviour are controlled by different microstructural parameters and not, as in the case of polygonal ferritic steels, by the same structural unit (the grain size) and that a “fine” microstructure is required in order to achieve high levels of both strength and toughness. The metallurgical design of high strength steels with toughness requirements is discussed using the same approach for both Q&T and TMCP processes.

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39

Bai, Bing, Chang Yi Zhang, Pei Pei Zhang, and Wen Yang. "Effect of Precipitate on Thermal Aging Effect of 17-4PH Martensitic Stainless Steel Used as Valve Stem in Nuclear Power Plant." Materials Science Forum 944 (January 2019): 466–72. http://dx.doi.org/10.4028/www.scientific.net/msf.944.466.

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The valve stem used in the main steam system of nuclear power plant is usually 17-4PH martensitic stainless steel. When it served in 300°C for a long time, the thermal aging embrittlement of valve stem will be significant, with the performance of the ductile brittle transition temperature (DBTT) and the hardness increased, the upper stage energy (USE) decreased. It will increase the risk of brittle fracture of the valve stem, and seriously affect the safety and economic operation of nuclear power plant (NPP). Similar cases have occurred in foreign nuclear power plants. Therefore, it is important to study the thermal aging effect of the 17-4PH steel used as valves in nuclear power plant. In this work, the 17-4PH martensitic stainless steel samples served in nuclear power plant for many years were studied, and they exhibit obvious thermal aging embrittlement. By use of small angle neutron scattering (SANS) and three-dimensional atomic probe (3DAP), the nanosize precipitate in stainless steel is studied. The results show that the size of the larger cluster (~7nm) in stainless steel increases and the volume fraction of the cluster with size of ~1nm increases obviously after thermal aging. The larger nanosize precipitate was growing up during long service at high temperature, and precipitation of the smaller ones continuously occurred. Combing with the results of 3DAP, the nanosize clusters were formed by segregation of Ni, Mn and other elements with Cu-rich cluster, which are mainly in the form of Cu core and Ni-Mn shell.

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Bhowmik, Sumit, Prasanta Sahoo, Sanjib Kumar Acharyya, Sankar Dhar, and Jayanta Chattopadhyay. "Effect of Microstructure Degradation on Fracture Toughness of 20MnMoNi55 Steel in DBT Region." International Journal of Manufacturing, Materials, and Mechanical Engineering 6, no. 3 (July 2016): 11–27. http://dx.doi.org/10.4018/ijmmme.2016070102.

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The paper considers the effect of microstructure degradation on fracture toughness of 20MnMoNi55 pressure vessel steel. This degradation is reflected through the shift of fracture toughness vs. temperature curve along the temperature axis and rise in reference temperature in ductile to brittle transition (DBT) region. Hardness also depends on the microstructure of metallic alloys. The present study explores the correlation between hardness and fracture toughness for different microstructures in order to calibrate loss in toughness from hardness. The master curve reference temperature and microhardness for different microstructures are measured experimentally. It is observed that there exists a fair linear relation between microhardness and reference temperature.

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41

Cicero, Sergio, and Sergio Arrieta. "Dealing with the Fracture Ductile-to-Brittle Transition Zone of Ferritic Steels Containing Notches: On the Applicability of the Master Curve." Metals 11, no. 5 (April 23, 2021): 691. http://dx.doi.org/10.3390/met11050691.

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Characterizing the fracture resistance of ferritic steels operating within their Ductile-to-Brittle Transition Zone (DBTZ) has been successfully addressed through the development of the well-known Master Curve (MC). This tool assumes that fracture, in the presence of crack-like defects, is controlled by weakest-link statistics and follows a three-parameter Weibull distribution. When dealing with notch-type defects, there is no standardized solution to predict the fracture resistance within the DBTZ, but the authors have published some works demonstrating that the MC can also be applied in different ways to characterize ferritic steels containing notches. One of these ways is the direct application of the MC methodology, providing a specific reference temperature (T0N) for each material and notch radius. This work reviews this initial attempt to apply the MC in notched conditions, assessing the validity of the main MC hypotheses (initially valid for cracked conditions) when analyzing notch-type defects and providing experimental validation on steels S275JR, S355J2, S460M and S690Q.

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42

Mori, Hiroaki, Hiroyuki Ogiwara, Kazuyoshi Saida, Hisashi Serizawa, Takanori Hirose, and Hiroyasu Tanigawa. "Laser Beam Welding for Reduced Activation Ferritic/Martensitic Steel F82H." Materials Science Forum 783-786 (May 2014): 2771–76. http://dx.doi.org/10.4028/www.scientific.net/msf.783-786.2771.

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A fusion reactor is expected as one of the new electric power sources in next generation. Reduced activation ferritic/martensitic steel F82H is planned to be used as a structural material for the blanket modules set on the inner wall of the reactor. However, especially in the case of laser beam welding (LBW), the weldability of the steel was not completely clarified. On the other hand, although post weld heat treatment (PWHT) should be conducted for the welds of the steel in accordance with general standards for chrome steels, the heat treatment conditions were uncertain. Therefore, adaptability of LBW as a joining method for the steel and the applicable PWHT conditions for the welded joints were investigated in this study. The effect of LBW conditions on weld penetration behavior were ascertained by observation of cross sections in the welds. The adequate PWHT conditions were confirmed in consideration of both hardness distributions measured in welds and ductile-brittle transition temperatures (DBTT) evaluated using Charpy impact test. Full penetration without weld defects such as hot cracking, porosity etc. was obtained for plates with the thickness of 4mm of the steel by control welding conditions. That means laser beam is one of useful welding heat sources to realize sound weld joints of the steel. In addition, due to select appropriate PWHT conditions, the hardness in welds was suppressed to the level of base metal and the toughness in the welded joints was improved to a practical level without the damage to base metal.

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Bayu-Aji, Leonardus B., and P. Pirouz. "Brittle-to-ductile transition temperature in InP." physica status solidi (a) 207, no. 5 (December 14, 2009): 1190–95. http://dx.doi.org/10.1002/pssa.200925347.

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44

Aikin, R. M. "On the ductile-to-brittle transition temperature in MoSi2." Scripta Metallurgica et Materialia 26, no. 7 (April 1992): 1025–30. http://dx.doi.org/10.1016/0956-716x(92)90224-3.

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45

SEO, Kenji, Jun-ichi MASAKI, Fumio NOGATA, and Masahiro KUSAKA. "Brittle fracture initiation of steel at the temperature of the ductile-to-brittle transition region. (1st report Criteria for ductile-to-brittle transition)." Transactions of the Japan Society of Mechanical Engineers Series A 53, no. 489 (1987): 905–10. http://dx.doi.org/10.1299/kikaia.53.905.

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46

Zhan, Guo-Dong, Mamoru Mitomo, Rong-Jun Xie, and Keiji Kurashima. "Ductile-to-brittle Transition in Superplastic Silicon Nitride Ceramics." Journal of Materials Research 17, no. 1 (January 2002): 149–55. http://dx.doi.org/10.1557/jmr.2002.0023.

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The ductile-to-brittle transition was observed in a superplastic silicon nitride nanoceramic. This transition depends on strain rates and deformation temperatures. Generally, the material exhibits ductility at low strain rates and high deformation temperatures. At 1600 °C, the material is brittle when the strain rates are higher than 10−3/s. At a fixed strain rate of 10−3/s, the material exhibits brittleness when the temperatures are lower than 1550 °C. Moreover, critical strain rate for the brittle to ductile transition depends on deformation temperature. The critical strain rates increase with increases in the deformation temperature. When the deformation temperature is 1700 °C, the critical strain rates reach a maximum at 10−2/s. The extent of superplastic deformation in the present material was found to be limited not by intergranular cavitation but by the initiation and growth of surface cracks.

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47

Li, G., M. Q. Jiang, F. Jiang, L. He, and J. Sun. "Temperature-induced ductile-to-brittle transition of bulk metallic glasses." Applied Physics Letters 102, no. 17 (April 29, 2013): 171901. http://dx.doi.org/10.1063/1.4803170.

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Nazari, Ali, and Amir Ali Milani. "RETRACTED: Ductile to Brittle Transition Temperature of Functionally Graded Steels." International Journal of Damage Mechanics 21, no. 2 (March 7, 2011): 191–205. http://dx.doi.org/10.1177/1056789511398270.

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Vogel, D., L. Newman, P. Deb, and D. H. Boone. "Ductile-to-brittle transition temperature behavior of platinum-modified coatings." Materials Science and Engineering 88 (April 1987): 227–31. http://dx.doi.org/10.1016/0025-5416(87)90089-9.

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50

Li, Lu-Lu, Yanqing Su, Irene J. Beyerlein, and Wei-Zhong Han. "Achieving room-temperature brittle-to-ductile transition in ultrafine layered Fe-Al alloys." Science Advances 6, no. 39 (September 2020): eabb6658. http://dx.doi.org/10.1126/sciadv.abb6658.

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Fe-Al compounds are of interest due to their combination of light weight, high strength, and wear and corrosion resistance, but new forms that are also ductile are needed for their widespread use. The challenge in developing Fe-Al compositions that are both lightweight and ductile lies in the intrinsic tradeoff between Al concentration and brittle-to-ductile transition temperature. Here, we show that a room-temperature, ductile-like response can be attained in a FeAl/FeAl2 layered composite. Transmission electron microscopy, nanomechanical testing, and ab initio calculations find a critical layer thickness on the order of 1 μm, below which the FeAl2 layer homogeneously codeforms with the FeAl layer. The FeAl2 layer undergoes a fundamental change from multimodal, contained slip to unimodal slip that is aligned and fully transmitting across the FeAl/FeAl2 interface. Lightweight Fe-Al alloys with room-temperature, ductile-like responses can inspire new applications in reactor systems and other structural applications for extreme environments.

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Journal articles on the topic 'Ductile-to brittle transition temperature (dbtt)'

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