摘要
50CrV4作为优质的Cr-Mn-V系列合金弹簧钢,经过等温淬火+回火热处理后,获得下贝氏体+回火马氏体+少量残留奥氏体+弥散分布的颗粒状碳化物的复相组织。用50CrV4带钢制成的汽车正时齿形链链板,经过热处理后,保证高疲劳强度的同时,又兼具较好的耐磨性。但是由于50CrV4中Cr、Mn、V的存在,使得50CrV4过冷奥氏体较为稳定,在热轧卷板时,冷却不能过快,否则易出现马氏体和贝氏体,导致卷板过程中开裂,所以在高温区停留时间较长,不可避免地存在不同程度的晶界氧化,对晶界氧化程度不同的50CrV4带钢分别进行晶界氧化深度检测并冲裁成链板,在同样的热处理条件下,制作出成品链条,分别测试链条的拉力和疲劳强度,得出不同程度的晶界氧化对链条拉力和疲劳强度的影响,通过对比分析发现,纵向晶界氧化会造成链条拉力降低和链条疲劳强度降低,横向晶界氧化比纵向晶界氧化对链条的拉力的影响更严重,并且严重降低链条的疲劳强度。
50CrV4 is a high-quality Cr-Mn-V series alloy spring steel.After isothermal quenching and tempering heat treatment,the duplex structure of lower bainite+tempered martensite+a small amount of retained austenite+dispersed granular carbide can be obtained.After heat treatment,the automotive timing toothed chain plate made of 50CrV4 strip steel can ensure high fatigue strength,and meanwhile,possess good wear resistance.However,due to the existence of Cr,Mn and V in 50CrV4,the undercooled austenite of 50CrV4 is relatively stable.During hot rolling,the cooling cannot be too fast,otherwise the martensite and bainite are prone to occur,leading to cracking in the process of coiling.Therefore,the residence time in the high temperature zone is relatively long,and there is inevitably grain boundary oxidation at different levels.50CrV4 strips with different grain boundary oxidation levels were studied.The grain boundary oxidation depth was detected.Then the strips were punched to chain plates,which were prepared to the finished chains under same heat treatment conditions.The tension and fatigue strength of chains were measured,and the effects of different degrees of grain boundary oxidation were obtained.Through comparative analysis,it was found that the longitudinal grain boundary oxidation could cause the decrease of tensile strength and fatigue strength.Moreover,the transverse grain boundary oxidation had a severer impact on the tensile strength than the longitudinal grain boundary oxidation.The fatigue strength of the chains would be seriously reduced.
作者
张孟九
谢爱军
逄宁宁
王绪珍
王魁
王俊杰
ZHANG Mengjiu;XIE Aijun;PANG Ningning;WANG Xuzhen;WANG Kui;WANG Junjie(Qingdao Choho Industrial Co.,Ltd.,Qingdao 266705,China)
出处
《物理测试》
CAS
2024年第1期44-49,共6页
Physics Examination and Testing
关键词
50CrV4钢
晶界氧化
疲劳强度
链条拉力
50CrV4 steel
grain boundary oxidation
fatigue strength
chain tension
