回火温度对42CrMo4高强钢力学性能及应力腐蚀敏感性的影响  

Effect of Tempering Temperature on Mechanical Properties and Stress Corrosion Sensitivity of 42CrMo4 High-strength Steel

作　　者：张度宝 李成涛[1] 方可伟[1] 罗坤杰[1] 王力[1] 武焕春 薛飞[1] ZHANG Dubao;LI Chengtao;FANG Kewei;LUO Kunjie;WANG Li;WU Huanchun;XUE Fei(Suzhou Nuclear Power Research Institute,Suzhou 215004,China)

机构地区：[1]苏州热工研究院有限公司,苏州215004

出　　处：《材料导报》2021年第16期16133-16137,共5页Materials Reports

基　　金：国家自然科学基金青年基金(51431004);国家重点研发计划(2016YFB0700404)。

摘　　要：以42CrMo4高强钢为研究对象,采用光学显微镜(OM)、慢应变拉伸(SSRT)和透射电镜(TEM)等研究了42CrMo4显微组织中碳化物形貌和分布随温度变化的情况及其对力学性能和应力腐蚀敏感性的影响。结果表明,42CrMo4高强钢在500~650℃回火后,组织均为回火索氏体,随着回火温度的提高,碳化物由片状不均匀分布逐渐转变为短棒状,最终呈颗粒状弥散分布于基体上;回火过程中碳化物由不均匀片状分布转变为颗粒状弥散分布是42CrMo4高强钢综合力学性能和抗应力腐蚀敏感性持续改善的主要原因。随着回火温度上升,42CrMo4高强钢0℃冲击韧性逐渐提高,拉伸强度逐渐降低;回火温度为500~600℃时,试样具有较高的应力腐蚀敏感性,且在相同热处理条件下E_(H)(42CrMo4充氢后的脆化指数)>E_(NaCl)(42CrMo4在3.5%(质量分数)NaCl介质中的脆化指数),回火温度为620~650℃时,E_(H)和E_(NaCl)均低于25%,具有较低的应力腐蚀敏感性。The effects of tempering temperature on the carbide morphology and distribution in 42CrMo4 microstructure and mechanical properties and stress corrosion sensitivity were researched by the optical microscopy(OM),slow strain tensile testing(SSRT)and transmission electron microscopy(TEM).The results showed that the metallographic structure of 42CrMo4 high-strength steel was tempered sorbite after tempering at 500—650℃,with the increase of tempering temperature,the carbide gradually changed from uneven flakes to short rods,and finally became granular and distributed dispersively on the substrate,which was the main reason for the continuous improvement of comprehensive mechanical properties and stress corrosion resistance.As the tempering temperature increased,the impact toughness of 0℃of 42CrMo4 increased and the tensile strength decreased.When the tempering temperature was from 500℃to 600℃,the samples had higher stress corrosion sensitivity and under the same heat treatment conditions,the E_(H)>E_(NaCl),when the tempering temperature was from 620℃to 650℃,both E_(H) and E_(NaCl) were lower than 25%,which had lower stress corrosion sensitivity.

关 键 词：42CrMo4 回火温度 金相组织 力学性能 应力腐蚀 慢应变拉伸 

分 类 号：TG174[金属学及工艺—金属表面处理]