600 MPa级汽车大梁钢疲劳极限确定和疲劳断裂原因分析  

Determination of Fatigue Limit and Analysis of Fatigue Fracture of 600 MPa Automobile Frame Steel

作　　者：卢军辉[1] 刘家琪[1] 仇圣桃[1] 干勇[1] LU Jun-hui;LIU Jia-qi;QIU Sheng-tao;GAN Yong(National Engineering Research Center of Continuous Casting Technology,CISRI,Beijing 100081,China)

机构地区：[1]钢铁研究总院连铸技术国家工程研究中心

出　　处：《科学技术与工程》2020年第1期135-140,共6页Science Technology and Engineering

摘　　要：为确定薄板坯连铸连轧(flexible thin slab rolling,FTSR)短流程生产线生产的600 MPa级汽车大梁钢是否满足装车要求,利用升降法研究了汽车大梁钢的抗疲劳性能。研究结果表明,采用对数试验应力-对数疲劳寿命拟合的方法要优于直接采用试验应力-疲劳寿命,计算得到了不同存活率下的P-S-N曲线,由图得到疲劳极限强度为294 MPa,经过数值计算得到的疲劳极限强度为287.1 MPa。采用扫描电子显微镜对疲劳试样进行了断口分析,发现疲劳断裂为韧性断裂,夹杂物为裂纹的起源,结合试验钢的性能指标和装车试用考核结果,确认FTSR生产线开发的600 MPa级汽车大梁钢满足装车使用要求。To determine whether a 600 MPa-grade automobile frame steel produced on the FTSR(flexible thin slab rolling)short process production line could meet the loading requirements,the fatigue resistance of automobile girder steel was studied using up-and-down method.It was found that the method of lg S-lg N fitting was better than S-N fitting(S:the test stress;N:the number of cycle),and obtained the probabilistic-S-N(or P-S-N)curves under different survival rates,from which the fatigue ultimate strength was determined to be 294 MPa,similar to 287.1 MPa from the numerical calculation.In addition,the fatigue fracture using scanning electron microscope was observed.It was found that the fatigue fracture was ductile fracture and the inclusion impurities were the original points of cracking.According to the performance index of test steel and the test results of loading and commissioning,it was confirmed that 600 MPa grade automobile frame steel developed by FTSR production line could meet the requirements of loading operation.

关 键 词：汽车大梁钢 升降法 疲劳极限强度 疲劳辉纹 

分 类 号：TG142.12[一般工业技术—材料科学与工程]