拉伸变形对高氮奥氏体不锈钢显微组织和耐腐蚀性能的影响  

Effect of Tensile Deformation on Microstructure and Corrosion Resistance of High Nitrogen Austenitic Stainless Steels

作　　者：郑椿 刘嘉斌[2] 江来珠 杨成 姜美雪 ZHENG Chun;LIU Jiabin;JIANG Laizhu;YANG Cheng;JIANG Meixue(Fujian Tsingtuo Special Steel Technology and Research Co.,Ltd.,Ningde 355006,China;School of Materials Science and Engineering,Zhejiang University,Hangzhou 310027,China)

机构地区：[1]福建青拓特钢技术研究有限公司,宁德355006 [2]浙江大学材料科学与工程学院,杭州310027

出　　处：《金属学报》2022年第2期193-205,共13页Acta Metallurgica Sinica

基　　金：福建省科技重大专项项目No.2017HZ0001-3。

摘　　要：对高氮奥氏体不锈钢QN1803和常规奥氏体不锈钢304进行了不同形变量的拉伸实验,通过EBSD、XRD和TEM分析了其形变组织和强韧化机制。采用电化学工作站、酸性介质腐蚀实验和OM、SEM分析了不同拉伸形变量下的耐腐蚀性能和腐蚀机理。随着拉伸形变量的增加,QN1803和304不锈钢的微观组织均出现由位错塞积到α’马氏体的转变。QN1803不锈钢的屈服强度比304不锈钢提高了26%,延伸率降低了约6.6%,其原因是QN1803不锈钢中N含量高、30%冷变形后产生50%马氏体所对应的温度(M_(d30))较低,拉伸过程中产生的形变马氏体含量低于304不锈钢,相变增韧效应不如304不锈钢充分。拉伸形变对QN1803和304不锈钢的晶间腐蚀影响不大,但其耐点腐蚀能力、耐硫酸腐蚀能力均有下降,其中QN1803不锈钢下降的幅度明显小于304不锈钢。主要原因是形变马氏体导致不锈钢表面钝化膜破坏和稳定性下降,使钝化膜在腐蚀中处于不稳定的溶解-生成状态,从而降低了形变后的耐腐蚀性能。总体而言,提高奥氏体不锈钢的N含量能够节约Ni元素的使用,大幅提高不锈钢屈服强度,略微损害延伸率,但显著提升拉伸形变条件下的耐点蚀和耐硫酸腐蚀性能。Nitrogen-alloyed austenitic stainless steel QN1803(2.0%Ni-3.5%Ni)has been developed to replace the conventional 304 stainless steel(8%Ni).Both the microstructure and the corrosion resistance of both types of stainless steels in the annealed state have been extensively studied,whereas those in the cold strained state have not been studied sufficiently.The aforementioned stainless steels often undergo cold forming processes during industrial applications,such as straightening,leveling,and bending,etc.,which may lead to the changes of microstructure and corrosion resistances as well as the performance.In this study,the tensile tests were performed with different tensile strains for both nitrogenalloyed QN1803 and the conventional 304 stainless steels.The microstructure and strengthening,as well as the toughening mechanisms were investigated using EBSD,XRD,and TEM.The corrosion resistance and its mechanism under different tensile strains were evaluated and analyzed via electrochemical workstation,acid corrosion tests,OM,and SEM.Notably,the microstructures of both QN1803 and 304 stainless steels are changed from dislocation plugging toα’martensite with the increase in tensile strain.The yield strength of QN1803 stainless steel is 26%higher,while its elongation is 6.6%lower than that of 304 stainless steels,respectively.This could be attributed to both the higher nitrogen content and the lower transition temperature of 50%martensite induced by 30%strain(M_(d30))for QN1803 stainless steel as compared with that for 304 stainless steel.As a result,the volume fraction of the strain-induced martensite for QN1803 stainless steel under tensile strain is lower,leading to the lower toughening effect than that of 304 stainless steel.Interestingly,the experiments show that the tensile strain has a minor effect on the intergranular corrosion whereas noticeably negative effect on both the pitting and the sulfuric acid corrosion resistances of both stainless steels.Not surprisingly,304 stainless steel undergoes a more remarkable

关 键 词：高氮奥氏体不锈钢 拉伸形变 形变马氏体 点腐蚀 晶间腐蚀 硫酸腐蚀 

分 类 号：TG142.1[一般工业技术—材料科学与工程]