摘要
为了计算表面强化钢的疲劳极限和局部失效概率,基于渗碳CrMn钢、渗碳CrNiW钢和渗氮CrNiW钢,设计了1种光滑试样和2种缺口试样,开展3种钢材的超高周疲劳试验。使用扫描电子显微镜对疲劳断口进行观察,分析3种钢材的S-N曲线并确定其失效模式。在高应力状态下,试样主要发生由表面加工缺陷与表面夹杂诱发的表面失效,在低应力状态下,试样主要发生由内部夹杂、不均匀基体组织及碎化区诱发的内部失效。使用纳米压痕法对3种钢材由表及里的微观硬度进行测定,渗碳CrMn钢、渗碳CrNiW钢的渗碳层深度分别为500μm与900μm,渗氮CrNiW钢的渗氮层深度为280μm。基于最薄弱环节理论构建了表面强化钢的局部失效概率预测模型,采用建立有限元模型的方法对局部等效应力进行计算,优化表面-内部局部失效概率计算模型的参数计算方法,并对3种钢材的疲劳极限和局部失效概率进行计算。结果表明,模型所计算的疲劳极限和试验结果较为吻合,两者的最大误差为5.37%。该模型计算出的表面局部失效概率和试验结果较为接近,计算的内部局部失效概率和试验结果偏差较小。
The work aims to calculate the fatigue limit and the local failure probability of surface-reinforced steel.A smooth specimen and two notched specimens were designed for carburized CrMn steel,carburized CrNiW steel and nitrided CrNiW steel,and very high cycle fatigue tests were carried out for the three steels.The fracture surfaces were observed using Scanning Electron Microscopy to analyze the S-N curves of the three steels and determine their failure modes.At high stresses,surface failures were mainly induced by surface machining defects and surface inclusions,while at low stresses,internal failures were mainly induced by internal inclusions,inhomogeneous matrix area and fine granular area.The micro-hardness of three steels from the surface to interior was measured by nano-indentation.The depth of the carburized layer for carburized CrMn steels and carburized CrNiW steels is 500μm and 900μm respectively,and the depth of the nitrided layer for nitrided CrNiW steels is 280μm.A prediction model for the local failure probability of surface-reinforced steel was constructed based on the weakest-link theory,the local equivalent force was calculated by using the method of establishing a finite element model,the parameter calculation method of this prediction model was optimized,and the fatigue limit and local failure probability of three steels were calculated.The results show that,the calculated fatigue limit by the model ties well with the test results,the maximum error between the two is 5.37%.The calculated local surface failure probability by the model is closer to the experimental results,and the deviations between calculated local interior failure probability and experimental results were small.
作者
孙振铎
吕松峰
李伟
庞彬
SUN Zhenduo;LÜSongfeng;LI Wei;PANG Bin(School of Quality and Technical Supervision,Hebei University,Baoding 071002,Hebei,China;Hebei Technology Innovation Center for Lightweight of New Energy Vehicle Power System,Baoding 071002,Hebei,China;School of Mechanical Engineering,Beijing Institute of Technology,Beijing 100081,China)
出处
《钢铁》
CAS
CSCD
北大核心
2024年第5期161-171,共11页
Iron and Steel
基金
国家自然科学基金资助项目(51775043)
河北省自然科学基金资助项目(E2018201265)
河北省高等学校科学技术研究资助项目(QN2017307)。
作者简介
孙振铎(1980—),男,博士,副教授,E-mail:bdsunzhenduo@126.com;通信作者:李伟(1979—),男,博士,副教授,E-mail:lliw@bit.edu.cn。
