摘要
为了提高Cr-Ni-Co-Mo马氏体时效不锈钢的耐腐蚀性能,本工作设计了高温固溶+时效(HS)、低温固溶+时效(LS)和循环固溶+时效(CLS)3种热处理工艺,研究了固溶处理方式对马氏体时效不锈钢晶粒尺寸、逆转变奥氏体体积分数的影响,并探究特征组织对马氏体时效不锈钢在3.5%NaCl(质量分数)溶液中的耐腐蚀性能的影响。结果表明,相比于高温固溶处理,低温固溶处理显著细化了马氏体板条块的尺寸(2.1μm→943 nm),逆转变奥氏体体积分数增加至7.8%。循环固溶处理通过引入高密度位错和残余奥氏体,为时效过程中逆转变奥氏体的形成提供了形核位点和元素扩散通道,逆转变奥氏体体积分数提高至33%。周期浸润腐蚀实验表明,晶粒细化和逆转变奥氏体体积分数的增加显著提高了材料的耐腐蚀性能。晶粒细化通过增加晶界密度,促进表面钝化膜的形成,降低材料的晶间腐蚀敏感度。逆转变奥氏体通过增加钝化膜的稳定性和厚度,提高点蚀区的电荷转移电阻,显著增强了材料在含Cl⁻环境中的抗点蚀能力。
Maraging stainless steel has extensive applications in aerospace,marine,and other de-manding fields because of its high strength.However,its susceptibility to pitting corrosion in Cl−-containing environments considerably limits its practical applications under corrosive conditions.This study investi-gates the effects of three solution treatments—high temperature solution(HS),low temperature solution(LS),and cyclic low temperature solution(CLS)—on grain size and reversed austenite formation in Cr-Ni-Co-Mo maraging stainless steel.Furthermore,it explores the relationship between its microstructure and corrosion resistance in a 3.5%NaCl(mass fraction)solution.The results revealed that the LS treatment refines the martensite block size from 2.1μm to 943 nm and increases the reversed austenite content from 1.9%to 7.8%compared with the HS treatment.The CLS treatment introduces a high density of dis-locations and retained austenite,which provide favorable nucleation sites and diffusion pathways for ele-mental redistribution during aging,thereby leading to a substantial increase in reversed austenite content to 33%.Cyclic infiltration corrosion tests and electrochemical measurements confirm that grain refine-ment and the enhanced reversed austenite content considerably improve the corrosion resistance.Grain refinement increases the density of grain boundaries,facilitates the formation of a passivation film on the surface and reduces susceptibility to intergranular corrosion.Compared with LS-treated steel,CLS-treated steel exhibits a 109 mVSCE increase in corrosion potential,an 86.25μA/cm2 decrease in corro-sion current density,and a 26.82 mVSCE increase in pitting potential.As the reversed austenite content increases,the total resistance of solution and the passivation film thickness increase,thereby improving the stability and protective performance of the passivation film.Concurrently,pitting charge transfer resistance increases,which improves resistance to pitting corrosion.
作者
杨佳伟
周德凯
赵利媛
王天宇
李小琳
杨洪波
王海丰
YANG Jiawei;ZHOU Dekai;ZHAO Liyuan;WANG Tianyu;LI Xiaolin;YANG Hongbo;WANG Haifeng(State Key Laboratory of Solidification Processing,School of Materials Science and Engineering,Northwestern Polytechnical University,Xi'an 710072,China;School of Metallurgical Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China)
出处
《金属学报》
北大核心
2025年第11期1715-1726,共12页
Acta Metallurgica Sinica
基金
国家重点研发计划项目No.2022YFB3705300
国家自然科学基金项目Nos.52374403,U23A20613和52004224
凝固技术全国重点实验室项目No.2021-TS-10
西北工业大学研究生创新能力培育基金项目No.PF2025040
分析测试中心研究基金项目No.2023-T-009。
关键词
马氏体时效不锈钢
晶粒细化
逆转变奥氏体
耐腐蚀机理
maraging stainless steel
grain refinement
reversed austenite
corrosion resistance mechanism
