预应变对高强结构钢低温断裂韧性的影响  

Effect of Prestrain on Fracture Toughness of High-Strength Structural Steel at Low Temperature

作　　者：肖光春[1,2] 荆洪阳[1,2] 徐连勇[1,2] 

机构地区：[1]天津大学材料科学与工程学院,天津300072 [2]天津市现代连接技术重点实验室,天津300072

出　　处：《天津大学学报》2011年第4期303-307,共5页Journal of Tianjin University(Science and Technology)

基　　金：国家自然科学基金资助项目(50975196);教育部博士点新教师基金资助项目(20070056096);高等学校博士学科点专项科研基金资助项目(20090032110026);天津市自然科学基金资助项目(08JCYBJC09100)

摘　　要：对高强结构钢Q420试样及具有2%预应变试样分别进行了不同温度下的拉伸试验和断裂韧性试验,测试了其力学性能和断裂韧性.试验结果表明,温度对结构钢的断裂韧性具有明显的作用,钢材的断裂韧性随着温度的降低显著减小,断裂方式也由延性断裂转变为脆性断裂;拉预应变因工作硬化提高了钢材的屈服强度与抗拉强度,而压预应变因包申格效应降低了钢材的屈服强度与抗拉强度,但两者都降低了钢材的塑性及断裂韧性,进一步增加了脆性断裂发生的可能性,而且压预应变对钢材断裂韧性的影响略大一些.为此,在重要工程设计、选材、安全分析及评定时,应充分考虑温度和预应变对结构断裂行为的影响.To investigate the mechanical properties and fracture toughness of high-strength structural steel subjected to 2% plastic deformation with tensile or compressive prestrain,tensile tests and crack tip opening displace-ment（CTOD）tests were conducted on Q420 steel.The results indicate that the temperature has a significant influence on fracture toughness of structural steel and the fracture toughness reduces significantly with the decrease of tempera-ture resulting to brittle fracture.The yield strength and tensile strength of the workpieces generally increase with ten-sile prestrain due to work hardening and decrease with compressed prestrain due to the Bauschinger effect.But both prestrains significantly reduce metal′s plasticity and fracture toughness,and further increase the possibility of brittle fracture.Compressive prestrain has a greater effect on the reduction of the critical fracture toughness than tensile pre-strain.Thus the effects of the temperature and the prestrain should be considered in the important engineering design,material selection and safety analysis and evaluation.

关 键 词：高强结构钢 预应变 力学性能 断裂韧性 

分 类 号：TG115.5[金属学及工艺—物理冶金]