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通过热模拟实验、光学金相及透射电镜分析观察,研究了奥氏体化条件、变形温度、变形速率、变形量以及道次间隔时间对曲轴用非调质钢C38N2轧制道次间的静态再结晶体积分数和残余应变率的影响规律.实验结果表明:随着变形温度的升高、变形速率的增大、变形量的增大或道次间间隔时间的增长,静态再结晶的体积分数逐渐升高,道次的残余应变率逐渐降低;原始奥氏体晶粒尺寸增大,静态再结晶体积分数降低,但变化不大;在1250℃以下,随着奥氏体化温度的升高,静态再结晶体积分数降低不明显,但在1250℃以上,奥氏体化温度的升高明显降低了静态再结晶体积分数.通过线性拟合以及最小二乘法,得到静态再结晶体积分数与不同变形工艺参数之间关系的数学模型;对已有残余应变率数学模型进行修正,得到含有应变速率项的残余应变率数学模型,拟合度较好.
The effects of austenitizing conditions, deformation temperature, deformation rate, deformation and interpass time on the static state of C38N2 rolling pass of crankshaft with non-quenched and tempered steel were studied by thermal simulation, optical metallography and transmission electron microscopy. Recrystallization volume fraction and residual strain rate.The experimental results show that with the increase of deformation temperature, the increase of deformation rate, the increase of deformation or the increase of interval time between passes, the volume fraction of static recrystallization And the residual strain rate of the passes decreased gradually. The grain size of the original austenite increased and the volume fraction of the static recrystallization decreased, but little changed. Under the temperature of 1250 ℃, with the increase of the austenitizing temperature , But the decrease of static recrystallization volume fraction is insignificant, but the increase of austenitizing temperature obviously reduces the volume fraction of static recrystallization above 1250 ℃ .Through linear fitting and least square method, the volume fraction of static recrystallization is different The mathematical model of the relationship between the deformation process parameters; the residual strain rate mathematical model has been amended to obtain the strain rate of the residual strain rate mathematical model, good fit.