回火温度对超高强钢微观组织及力学性能的影响  

Effect of tempering temperature on microstructure and mechanical properties of ultra-high strength steel

作　　者：郑东升 刘丹[2] 罗登[2] 李慧中[3] 张青学[2] 张永东[2] 杨小军[2] ZHENG Dong-sheng;LIU Dan;LUO Deng;LI Hui-zhong;ZHANG Qing-xue;ZHANG Yong-dong;YANG Xiao-jun(College of Metallurgy and Material Engineering,Hunan University of Technology,Zhuzhou 412007,China;Technology and Quality Department,Xiangtan Iron and Steel Co Ltd of Hunan Valin,Xiangtan 411101,China;School of Materials Science and Engineering,Central South University,Changsha 410083,China)

机构地区：[1]湖南工业大学冶金与材料工程学院,湖南株洲412007 [2]湖南华菱湘潭钢铁有限公司技术质量部,湖南湘潭411101 [3]中南大学材料科学与工程学院,湖南长沙410083

出　　处：《材料热处理学报》2020年第12期90-96,共7页Transactions of Materials and Heat Treatment

基　　金：湖南省教育厅科学研究项目(19C0574);湖南省科技创新计划项目(2018XK2301)。

摘　　要：研究了回火温度对超高强钢微观组织及力学性能的影响,并借助扫描电镜、透射电镜分析了马氏体基体中铁的碳化物特征、微合金碳氮化物析出,马氏体板条内的位错形态以及冲击试样断口特征。结果表明:回火温度在150~600℃时,随着回火温度的升高,铁的碳化物从板条内析出过渡到板条间析出、晶界析出,并逐步粗化、近球化,细小微合金碳氮化物的析出量变化不明显,马氏体板条内的位错趋于平直化,位错密度不断下降。随着回火温度的升高,超高强钢的屈服强度先增大而后减小,抗拉强度单调降低,伸长率和-40℃冲击吸收能量的变化趋势相同,并在回火温度300℃时出现最小值。随着回火温度的变化,-40℃冲击试样的不稳定断裂区呈现出韧性断裂、准解理断裂以及混合断裂多种类型。Effect of tempering temperature on microstructure and mechanical properties of ultra-high strength steel was studied.The characteristics of iron carbides and microalloy carbonitrides precipitation in the martensite matrix,dislocation configuration in martensite lath and fracture characteristics of impact specimens were analyzed by scanning electron microscopy(SEM)and transmission electron microscopy(TEM).The results show that when the tempering temperature is 150-600℃,with the increase of tempering temperature,the iron carbide precipitates from intra-lath to inter-lath and grain boundary,and gradually coarsens and nearly spheroidizes.The precipitation amount of fine microalloyed carbonitride does not change obviously.The dislocation in martensite lath tends to be flattened and the dislocation density decreases.With the increase of tempering temperature,the yield strength of the ultra-high strength steel first increases and then decreases,the tensile strength decreases monotonically,and the change trend of the elongation and impact absorption energy at-40℃is the same,and the minimum value appears at the tempering temperature of 300℃.With the change of tempering temperature,the unstable fracture zone of-40℃impact specimen exhibits ductile fracture,quasi cleavage fracture and mixed fracture.

关 键 词：回火温度 超高强钢 马氏体 碳化物 微观组织 力学性能 

分 类 号：TG142.3[一般工业技术—材料科学与工程]