摘要
通过系统性试验分析手段,重点解析奥氏体不锈钢渗氮层在滑动接触工况下的失效机理。采用金相显微观察与扫描电镜表征相结合的方法,明确渗氮层宏观、微观组织特征;基于维氏硬度梯度测试与能谱分析,定量评估渗氮层-基体界面硬度突变及Cr元素偏析对界面力学失配的协同作用;通过3点弯曲试验验证硬度梯度与成分偏析对渗氮层抗裂纹扩展能力的影响,揭示界面脆性主导的层状剥落失效模式。结果表明:渗氮层整体Cr含量较基体下降18.7%,导致抗氧化性降低;同时,晶界处富Cr氮化物析出相显著增加晶界脆性。渗氮层与基体间剧烈的硬度梯度导致界面力学性能失配,在铜环滑动过程中诱发裂纹沿脆性晶界扩展,最终引发渗氮层剥落。研究首次建立了中温渗氮条件下“硬度梯度-成分偏析-弯曲性能”的关系,为渗氮层界面稳定性评估提供了试验依据。
This study focuses on analyzing the failure mechanism of the nitriding layer of austenitic stainless steel under sliding contact conditions through systematic experimental analysis methods.By combining metallographic microscopy observation with scanning electron microscopy characterization,the macroscopic,microscopic structural characteristics of the nitrided layer are clarified;Based on Vickers hardness gradient testing and energy spectrum analysis,quantitatively evaluate the synergistic effect of sudden hardness changes and Cr element segregation on the interface mechanical mismatch between the nitriding layer and the substrate interface;Through three-point bending experiments,the influence of hardness gradient and composition segregation on the crack propagation resistance of the nitriding layer was verified,revealing the layered peeling failure mode dominated by interface brittleness.The results showed that the overall Cr content of the nitriding layer decreased by 18.7%compared to the matrix,leading to a decrease in oxidation resistance;At the same time,the precipitation of Cr rich nitrides at grain boundaries significantly increases grain boundary brittleness.The severe hardness gradient between the nitriding layer and the substrate leads to a mismatch in the mechanical properties of the interface,which induces cracks to propagate along brittle grain boundaries during the sliding process of the copper ring,ultimately causing the nitriding layer to peel off.The study established for the first time a quantitative relationship between"hardness gradient composition segregation bending performance"under medium temperature nitriding conditions,providing experimental evidence for evaluating the stability of the nitriding layer interface.
作者
姜君
季昕阳
李栋
吴国清
JIANG Jun;JI Xinyang;LI Dong;WU Guoqing(China Institute of Atomic Energy,Beijing 102413,China;Linyi High Tech Zone Shuanghang Material Technology Co.,Ltd.,Linyi 276000,Shandong,China;School of Materials Science and Engineering,Linyi University,Linyi 276000,Shandong,China;School of Materials Science and Engineering,Beihang University,Beijing 100191,China)
基金
钛合金大型复杂铸件组织均匀性评估项目(HX230240)
铸造、机械加工技术咨询服务项目(HX240385)
基于大数据建模的企业产品开发与质量评估研究项目(HX250280)。
关键词
密封筒
奥氏体不锈钢
离子渗氮
腐蚀磨损
sealing cylinder
austenitic stainless steel
ion nitriding
corrosion wear
