检索结果-南通市图书馆

Journal of materials Science & Technology 2006年第3期22卷 382-386页

作者： Lin ZHAO Wuzhu CHEN Wudong ZHANG Jiguo SHAN Department of mechanical Engineering Tsinghua University Beijing 100084 China Key Laboratory for Advanced materials Processing Technology Ministry of Education Tsinghua University Beijing 100084 China

800 mPa grade new ultra-low carbon bainitic （NULCB） steel is the recently developed new generation steel. The microstructure in the coarse-grained heat affected zone （CGHAZ） of NULCB steel under laser welding conditions was investigated by thermal simulation. The influence of the cooling time from 800℃ to 500℃.t8/5 （0.3-30 s）, on the microstructure of the CGHAZ was discussed. The experimental results indicate that the microstructnre of the CGHAZ is only the granular bainite which consists of bainitic ferrite （BF） lath and m-a constituent while t8/5 is 0.3-30 s. The m-a constituent consists of twinned martensite and residual austenite, and the change of the volume fraction of the residual austenite in the m-a constituent is very small when t8/5 is between 0.3 and 30 s. The morphology of the m-a constituent obviously changes with the variation of t8/5.As t8/5 increases, tile average width, gross and shape parameter of the m-a constituent increase, while the line density of the m-a constituent decreases.

关键词： Laser welding New ultra-low carbon bainitic steel Coarse-grained heat-affected zone microstructure m-a constituent

RELATIONSHIP BETWEEN m-a constituent AND CLEAVAGE FRACTURE BEHAVIOUR OF GRANULAR BAINITIC WELD mETAL

在线全文

学校读者我要写书评

暂无评论

Acta metallurgica Sinica(English Letters) 1989年第2期2卷 143-146页

作者： XU Xiangxing SU Yi ZHOU Wei Tsinghua University,Beijing,ChinaCAI Qigong Central Iron and Steel Research Institute,ministry of metallurgical Industry,Beijing,China XU Xiangxing,Dept.of mechanical Engineering,Tsinghua University,Beijing,100084,China

The cleavage fracture mechanism of granular bainitie weld metal in 15mnVN steel has been investigated.SEm observation of a special specimen for revealing simultaneously fracture sur- face and microstructure shows that the cleavage of the weld is initiated by m-a constituent. The 95th percentile equivalent diameter of m-a constituent controls the cleavage fracture stress of the weld metal.

关键词： granular bainite m-a constituent weld cleavage fracture

Investigation of m-a constituent in Weld CGHAZ of High-strength microalloyed Steel

在线全文

学校读者我要写书评

暂无评论

Investigation of M-A Constituent in Weld CGHAZ of High-stren...

microstructural refinement mechanism and its effect on toughness in the nugget zone of high-strength pipeline steel by friction stir welding

第五届国际材料与热加工物理模拟及数值模拟学术会议

作者： Chen Cuixin Peng Huifen Dong Tianshun (School of materials science and Engineering Hebei University of Technology Tian Jin 300130 China)

Thermal simulating technology was used to simulate weld CGHAZ of microalloyed steel with different thermal cycle for the purpose of investigation on morphology of m-a constituent and its influence on toughness. The experimental results showed that in comparison with base metal specimens after thermal cycle have poorer toughness for its larger size, englongated and sharp massive shape and non-uniform distribution. Toughness of specimen value has maximum value with maximum area fraction for cooling time of 7s, and then it will drop whether cooling time is longer or shorter. moreover, its mean chords of all specimens are all smaller than 0.5μm. Only those with the length larger than 2μm or the length-width ratio exceeding 4, cleavage fracture can occur. So it is concluded that m-a constituent is not the main influencing factor of impairing toughness for steel with different thermal cycle for its smaller mean chord and area fraction.

关键词： microalloyed steel m-a constituent shape toughness

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2021年第34期93卷 221-231页

作者： R.H.Duan G.m.Xie P.Xue Z.Y.ma Z.A.Luo C.Wang R.D.K.misra State Key Laboratory of Rolling and Automation Northeastern UniversityNo.3 Wenhua RoadShenyang 110819China Shi-changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of metallurgy Northeastern UniversityNo.3 Wenhua RoadShenyang 110819China Department of metallurgical Materialsand Biomedical EngineeringUniversity of Texas at El PasoTX 79968USA

High-strength pipeline steel was subjected to friction stir welding(FSW)at rotation rates of 400-700 rpm,and the grain refinement mechanism of the nugget zone(NZ)was determined.The thermomechanical process during FSW in the NZ was simulated by multi-pass thermal compression,thereby achieving the austenitic non-recrystallization temperature(T_(nr)).The austenitic non-recrystallization in the NZ at the lowest rotation rate of 400 rpm caused a significant grain refinement.Furthermore,the reduced rotation rate also resulted in the formation of a high ratio of island-like martensite-austenite(m-A)constituent.The toughness of the NZs was enhanced as the rotation rate decreased,which is attributed to the fine effective grains and homogeneously distributed fine m-a constituents dramatically inhibiting crack initiation and propagation.

关键词： Pipeline steel Friction stir welding Grain refinement m-a constituent Toughness

microstructure and Property of Coarse Grain HAZ X80 Pipeline Steel

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research(International) 2005年第6期12卷 54-58页

作者： ZHOU Yun XUE Xiao-huai QIAN Bai-nian LI Jing-li SHAN Yi-Yin LOU Song-nian Shanghai Jiaotong University Shanghai 200030 China Academia Sinica Shenyang 110015 China

The coarse grain HAZ microstructure and property of X80 pipeline steel with different carbon content was investigated. The weld thermal simulation test was carried out on Gleeble 1500 thermal mechanical test machine. The Charpy tests were completed at --20 ℃ for evaluating the toughness of coarse grain heat affected zone （CGHAZ）. The microstructure was examined by optical microscope （Om） and transmission electron microscopy （TEm）, and the austenite constituent was quantified by X-ray diffraction. The results showed that the ultra-low carbon can improve the toughness of CGHAZ by suppressing the formation of carbide, decreasing the martensite austenite （m-A） constituent and increasing the residual austenite in the m A.

关键词： X80 pipeline steel CGHAZ weld simulation FesC carbide ultra low carbon m-a constituent bainitic ferrite

Cold cracking susceptibility of X100 pipeline steel

在线全文

学校读者我要写书评

暂无评论

China Welding 2019年第3期28卷 25-33页

作者：严春妍姜心怡元媛纪秀林张可召 College of mechanical and Electrical Engineering Hohai UniversityChangzhou 213022China CRRC Zhuzhou Locomotive Co. Ltd.Zhuzhou 412001China

The y-groove Tekken test has been performed to evaluate the cold cracking susceptibility of X100 pipeline steel.The impact of preheating state on the microstructure,distribution of hardness,and the stress-strain state in the welded joint was analyzed.The results show that X100 pipeline steel reveals a low susceptibility to cold cracking with cracking ratios below 20%.It is found that elevated preheating temperature leads to longer cooling time in the welded specimen and ultimately results in a lower cold cracking susceptibility.Preheating temperatures of up to 100℃ are favorable in decreasing the cold cracking susceptibility due to a relative fine microstructure and low m-a constituent amount in coarse grained heat affected zone,a low hardenability,and low-level residual stress and strain.However,excessive preheating temperatures of 150℃ and 200℃ lead to grain coarsening,higher m-a constituent amount,higher residual stress level and increasing strain level in the Tekken specimens.Preheating temperature above 150℃is not favorable for decreasing the cold cracking susceptibility of X100 steel.

关键词： numerical simulation temperature field residual stress strain m-a constituent