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针对49MnVS3曲轴产品服役寿命低的问题,本文对与曲轴随炉处理的标准拉伸试样进行了拉伸试验和疲劳试验。结果表明,试样的伸长率偏低(8.53%);99%存活率下的疲劳极限值仅为340.25 MPa。据此,对试样晶粒度展开评估,并对正火温度与晶粒度之间的关系进行了深入研究。结果表明,随着正火温度的增加,晶粒逐渐长大,晶粒度减小;当温度超过1180℃时,晶粒度等级低于4级,出现“过热”现象。
In order to solve the problem of low service life of 49MnVS3 crankshaft products, tensile test and fatigue test of standard tensile specimens treated with crankshaft with furnace were carried out in this paper. The results show that the elongation of the sample is low (8.53%) and the fatigue limit of 99.25% is only 340.25 MPa. Based on this, the grain size of the sample is evaluated, and the relationship between the normalizing temperature and the grain size is further studied. The results show that with the increase of normalizing temperature, the grains grow up and the grain size decreases. When the temperature exceeds 1180 ℃, the grade of grain size is below grade 4 and “overheating” appears.