超细晶粒高强度钢的延迟断裂行为  

DELAYED FRACTURE BEHAVIOR OF ULTRAFINE GRAINED HIGH STRENGTH STEEL

作　　者：惠卫军[1] 董瀚[1] 翁宇庆[2] 时捷[1] 聂义宏[1] 褚作明[3] 陈蕴博[3] 

机构地区：[1]钢铁研究总院结构材料研究所,北京100081 [2]中国金属学会,北京100711 [3]北京机电研究所,北京100083

出　　处：《金属学报》2004年第6期561-568,共8页Acta Metallurgica Sinica

基　　金：国家重点基础研究发展规划项目G1998061503;"十五"国家科技攻关计划项目2002BA314B08资助

摘　　要：对于微合金化处理的42CrMoVNb钢,通过快速循环热处理的方法获得最小2μm的超细奥氏体晶粒,采用缺口拉伸延迟断裂实验研究了超细晶粒试样的延迟断裂行为.结果表明,随着晶粒细化,42CrMoVNb钢的强度和缺口拉伸延迟断裂抗力逐渐提高;但当晶粒细化到2μm时,强度和延迟断裂抗力均不再提高.在高温回火态,当晶粒尺寸在20-4μm范围时,断裂机制主要为穿晶断裂;但当晶粒进一步细化到2μm时,断裂机制转变为沿晶断裂.在低温回火态,不同晶粒尺寸的试样均主要为沿晶断裂.从降低应力集中和夹杂元素晶界偏聚等角度对超细晶粒高强度钢的延迟断裂行为进行了探讨.42CrMoVNb steel with ultrafine prior austenite grain, its size as fine as 2 mum, was obtained through rapidly cycle heat treatment. The effect of ultrafine grain size on delayed fracture behavior is studied using sustained load tensile test with notched specimen. It is shown that both strength and delayed fracture resistance of 42CrMoVNb steel increase when its grain size is refined from 20 mum to 4 mum, but they do not increase when refined to 2 mum. When the steel was tempered at high temperature, its fracture characteristic at crack initiation area changes from intergranular to transgranular when its grain size is refined from 20 mum to 8-4 mum, while the fracture characteristic is intergranular when its grain size is refined to 2 mum. Its fracture characteristics are all intergranular fracture for all the grain sizes investigated when tempered at low temperature. The reason for this kind of delayed fracture behavior is discussed mainly from the stress concentration and segregation at grain boundary.

关 键 词：超细晶粒 延迟断裂行为 高强度钢 

分 类 号：TG111.91[金属学及工艺—物理冶金] TG142[金属学及工艺—金属学]