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Effect of stress-relief annealing on thermal fatigue cracks for die-casting die steels

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Journal of Iron and Steel Research International 2024年第5期31卷 1164-1176页

作者： Zhi-xiong Bai Xiao-chun Wu School of Materials Science and Engineering Shanghai UniversityShanghai200444China

The effect of stress-relief annealing at different stages of thermal fatigue tests on crack growth was investigated using a self-built thermal cycle *** results showed that annealing could limit crack expansion *** reduced dislocation density and released the accumulation of residual *** addition,the strain accumulation in carbides was reduced by this *** was also found that double annealing was even more effective at inhibiting crack expansion compared to single stress-relief *** 1000 cycles,the maximum crack length was reduced by 31.1%and 45.2%for the samples after using the optimal single and double annealing processes,*** single stress-relief annealing,earlier annealing provides more benefit in delaying crack ***,effective double stress-relief annealing requires a suitable time interval between the annealing ***,after 800 cycles,surface hardness decreased significantly accompanied by an increase in the size and number of carbides,and cracks expanded predominantly along grain boundaries.

关键词： thermal fatigue Steel Carbide Stress-relief annealing Dislocation Residual stress

thermal fatigue behavior of K465 superalloy

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Rare Metals 2006年第3期25卷 202-209页

作者： YANG Jinxia ZHENG Qi SUN Xiaofeng GUAN Hengrong HU Zhuangqi Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

The thermal fatigue behavior of K465 superalloy was investigated at the peak temperature of 1050℃. By scanning electron microscopy （SEM） and optical microscopy, the main crack length was observed and measured. The initiation sites of the tested alloys are different in as-cast （named as K465） and solution heat treatment （named as SK465） conditions. In K465 alloy, most thermal fatigue cracks nucleate at （Nb,W,Ti）C carbides. In SK465 alloy, thermal fatigue cracks initiate in interdendritic regions, MC-type carbides and some interfaces. thermal fatigue cracks propagate in transdendritic mode, and M6C-type carbides could retard thermal fatigue crack growth for SK465 superalloy.

关键词： K465 superalloy thermal fatigue crack initiation and growth carbides

thermal fatigue behavior of 441 ferritic stainless steel in air and synthetic automotive exhaust gas

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Science China(Technological Sciences) 2022年第1期65卷 169-178页

作者： ZHAN JianMing BI HongYun LI MouCheng Materials Genome Institute Shanghai UniversityShanghai 200072China Research Institute Baoshan Iron&Steel Co.Ltd.Shanghai 200431China Institute of Materials School of Materials Science and EngineeringShanghai UniversityShanghai 200072China

The thermal fatigue behavior of 441 ferritic stainless steel was investigated in air and synthetic automotive exhaust gas by the cyclic tests under 100℃-800℃ and 900℃ *** the fracture failure,the microstructure,oxide film,and precipitated phases were analyzed using optical microscopy,X-ray diffraction,scanning electron microscopy,and transmission electron *** both atmospheres,increasing the maximum temperature from 800℃ to 900℃ results in lower strength and fatigue life and higher elongation and grain *** the same maximum temperature,the thermal fatigue life of the specimen is lower in the synthetic exhaust gas than in the *** the higher maximum temperature and the synthetic exhaust gas facilitate fatigue *** failure mechanism is discussed according to the grain size,thermal stress,high-temperature oxidation rate,and the precipitation of secondary *** precipitated carbides play an important role in the rapid fatigue failure of specimens in the synthetic exhaust gas.

关键词： stainless steel automobile exhaust gas thermal fatigue oxidation precipitation

thermal fatigue Behaviour of a Chromium Electroplated 32NiCrMo145 Steel

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Journal of Materials Science & Technology 2004年第3期20卷 269-273页

作者： A.Abdollah-zadeh M.S.Jamshidi S.M.M.Hadavi Department of Materials Engineering Tarbiat Modarres UniversityP.O.Box 14115-143TehranIranGST Research CenterP.O.Box 13185-665TehranIranSchool of Materials science and EngineeringMalekashtar UniversityP.O.Box 17665-3197TehranIran

thermal fatigue behavior of hard chromium electroplated steel in three different crack intensities of high contraction(HC), medium contraction (MC) and low contraction (LC) was studied. Maximum and minimum temperaturesduring thermal cycle were 800 and 100℃, respectively. The topography and cross sections of the samples exposedto 50, 100 and 200 thermal cycles were studied. The thermal fatigue behavior was analyzed using the data obtainedfrom surface roughness, crack networks and stress induced during cycles. Although the as-coated sample with LCchromium contained no crack, it appeared to have a high crack density after only 50 cycles. The crack depth andwidth in cyclically oxidized LC coating were much less than those in MC and HC coatings. It was concluded that theLC coating protected the substrate from having cracks or subsurface oxidation during thermal fatigue. The cracksin the HC and MC coatings increased in density as well as in depth by thermal cycles. Moreover, the opening of thecracks to the substrate resulted in sub-surface oxidation.

关键词： thermal fatigue Hard chromium plating 32NiCrMo145 steel

thermal fatigue Behavior of Ni_3Al Based Superalloy IC6E

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Chinese Journal of Aeronautics 2006年第B12期19卷 1-4页

作者： JI Lei LI Shu-suo HAN Ya-fang JIANG Li-wu School of Materials Science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The thermal fatigue behavior of Ni3Al based superalloy IC6E during the cycles between 900 ℃/1 000 ℃ and the room tempera- ture was investigated. The experimental results indicate that the primary and secondary thermal fatigue cracks initiate inside or round the borides and then spread away along grain boundaries and/or in interdendritic areas. The fracture of borides and their separation from the matrix at interfaces are mainly responsible for the crack initiation and its spreading. At temperatures higher than 1 000 ℃, the grain boundary oxidation combined with cyclic stresses accelerates the crack growth.

关键词： Ni3Al thermal fatigue cast superalloy

thermal　fatigue　Study　on　the　Divertor　Plate　Materials

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Plasma Science and Technology 2002年第5期4卷 1463-1468页

作者：吴继红张斧许增裕严建成 Southwestern Institute of Physics Chengdu 610041 China

thermal fatigue property of the divertor plate is one of the key issues that governs the lifetime of the divertor plate. Taking tungsten as surface material, a small-mock-up divertor plate was made by hot isostatic press welding (HIP). A thermal cycling experiment for divertor mock-up was carried out in the vacuum, where a high-heat-flux electronic gun was used as the thermal source. A cyclic heat flux of 9 MW/m2 was loaded onto the mock-up, a heating duration of 20 s was selected, the cooling water flow rate was 80 ml/s. After 1000 cycles, the surface and the W/Cu joint of the mock-up did not show any damage. The SEM was used to analyze the microstructure of the welding joint, where no cracks were found also.

关键词： fusion reactor divertor-plate materials thermal fatigue divertor mock-up

Influence of microstructures on thermal fatigue property of a nickel-base superalloy

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Frontiers of Materials Science 2015年第1期9卷 85-92页

作者： Peng-Cheng XIA Feng-Wen CHEN Kun XIE Ling QIAO Jin-Jiang YU College of Materials Science and Engineering Shandong University of Science and Technology Qingdao 266590 China Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

Effect of microstructures such as the distribution and shape of carbide and y＇ phase on thermal fatigue property of a superalloy was investigated experimentally. The resistance of thermal fatigue of the studied alloy decreases with the rising upper temperature. For the as-cast alloy, the thermal fatigue crack mostly origins from carbide at low upper temperature and results from oxidation at high upper temperature. The thermal fatigue crack of the heat treated alloy is mainly initiated by the oxidized cavity and then propagates through the join of the oxidized cavity. The orientation of crack propagation and direction of dendrite growth of alloy have the angle of 45°. There is y＂ denuded region near the thermal fatigue crack because of oxidation.

关键词： nickel-base superalloy thermal fatigue microstructure crack

The Intrinsic Relationship Between Microstructure Evolution and thermal fatigue Behavior of a Single-Crystal Cobalt-Base Superalloy

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Acta Metallurgica Sinica(English Letters) 2017年第12期30卷 1192-1200页

作者： Wei-Min Gui Hong-Yu Zhang Min Yang Tao Jin Xiao-Feng Sun Qi Zheng Superalloys Division Institute of Metal ResearchChinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China State Key Laboratory of Solidification Processing Northwestern Polytechnical University

The intrinsic relationship between the microstructure evolution and thermal fatigue behavior of a single-crystal cobalt-base superalloy has been investigated. The thermal fatigue tests are performed cyclically between room temperature and 1050 ℃ using V-notch plate specimens. Three states of thermal fatigue specimens are selected： the as-cast, solutionized as well as aged states. The solution treatment is carried out at 1260 ℃ for 24 h, which results in the dissolution of most of interdendritic continuous primary carbides. The subsequent aging treatment is carried out at 1100 ℃ for 100 h after solution treatment, resulting in the precipitation of a profusion of chain- and point-like M23C6 carbides in the matrix. The results indicate that the heat treatment can improve the thermal fatigue properties of the alloy and the effect of the solution treatment is more prominent than that of the aging treatment. The coarse and continuously distributed primary carbides in the as-cast state are changed into small and discontinuous distribution by heat treatment, which is the dominant factor in the improvement of thermal fatigue property. Additionally, the effect of oxidation behavior during thermal fatigue test on the thermal fatigue behavior is also studied.

关键词： Cobalt-base superalloys Heat treatment thermal fatigue Carbide Oxidation

Finite Element Simulation on thermal fatigue of a Turbine Blade with thermal Barrier Coatings

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Journal of Materials Science & Technology 2014年第4期30卷 371-380页

作者： L.Yang Q.X.Liu Y.C.Zhou W.G.Mao C.Lu Key Laboratory of Low Dimensional Materials & Application Technology(Ministry of Education) Xiangtan University Faculty of Materials Optoelectronic & PhysicsXiangtan University Department of Mechanical Engineering Curtin University

In this paper, a finite element model was developed for a turbine blade with thermal barrier coatings to investigate its failure behavior under cyclic thermal loading. Based on temperature and stress fields obtained from finite element simulations, dangerous regions in ceramic coating were determined in terms of the maximum principal stress criterion. The results show that damage preferentially occurs in the chamfer and rabbet of a turbine blade with thermal barrier coatings and its thermal fatigue life decreases with the increase of thermal stress induced by high service temperature.

关键词： Turbine blade thermal barrier coatings Finite element model thermal fatigue Life prediction