亚温淬火下组织形态对高强低合金钢冲击韧性的影响  

Effect of microstructure on impact toughness of a high strength low alloy steel processed by intercritical quenching

作　　者：康健[1] 袁国[1] 王国栋[1] 

机构地区：[1]东北大学轧制技术及连轧自动化国家重点实验室,辽宁沈阳110819

出　　处：《材料热处理学报》2015年第12期152-157,共6页Transactions of Materials and Heat Treatment

基　　金：国家科技支撑计划项目(2012BAF04B01)

摘　　要：以一种高强度低合金钢为研究对象,分析了淬火-亚温淬火-回火(RQ-IQ-T)工艺与控轧控冷-亚温淬火-回火(TMCP-IQT)工艺对组织演变及力学性能的影响,并对不同显微组织特征实验钢的冲击断裂行为进行讨论。结果表明:RQ-IQ-T工艺获得的显微组织由条状铁素体与回火马氏体构成,试样-40℃冲击功达到205 J;而TMCP-IQ-T工艺获得的显微组织则由块状铁素体与回火马氏体组成,试样具有较高的强度,但冲击功相对较低,仅为149 J。冲击裂纹在条状铁素体中扩展包括沿长轴方向和剪切条状铁素体两种方式;在块状铁素体中主要以穿晶方式进行扩展。经RQ-IQ-T工艺获得的条状铁素体与回火马氏体双相组织对裂纹扩展具有较大的阻碍作用,有利于冲击韧性的提高。Effects of reheated quenching-intercritical quenching-tempering（ RQ-IQ-T） and thermo-mechanical control process-intercritical quenching-tempering（ TMCP-IQ-T） processes on microstructural evolution and mechanical properties of a high-strength low-alloy（ HSLA）steel were studied. And the impact fracture behavior of the steel with different microstructural characteristics was discussed. The results show that a composite microstructure of banded ferrite and tempered martensite is obtained by RQ-IQ-T process,and the Charpy impact energy at- 40 ℃ is 205 J. However,the microstructure is composed of massive ferrite and tempered martensite for TMCP-IQ-T process.And the steel has higher strength and lower impact energy,being only 149 J at- 40 ℃. Two crack propagation path models are observed in banded ferrite： along the long axis direction,and across the banded ferrite. However,cracks in massive ferrite can propagate in a transgranular mode. The higher impact toughness for RQ-IQ-T is attributed mainly to the dual phase structure of banded ferrite and tempered martensite,which can exhibite effective resistance to the crack propagation.

关 键 词：亚温淬火 高强度低合金钢 显微组织 冲击韧性 裂纹扩展 

分 类 号：TG142.41[一般工业技术—材料科学与工程]