无磁钻铤用P550钢热变形行为

Hot deformation behavior of P550 steel for non-magnetic drill collars

采用THERMECMASTOR-Z型热模拟试验机在900~1200℃温度和0.01~10 s^(-1)应变速率下进行了热压缩实验,研究了无磁钻铤用P550钢的热变形行为,通过对真应力-真应变曲线的分析,建立了其峰值应力下的本构方程,并考虑了变形对应力的影响,建立了应变补偿优化后的本构方程。研究结果表明,P550钢的流动应力随变形温度的升高和应变速率的降低而减小,而且该本构方程具有较高的预测精度,相关系数和平均相对绝对误差分别为0.99%和6.70%,绝对误差在20 MPa以内的数据占比为91.05%,从而验证了模型的准确性和指导性。此外,基于动态材料模型构建了P550钢的热加工图,并结合微观组织分析发现,900℃时未发生再结晶,随着温度升高,再结晶程度明显增大。得到了优化后的热加工参数:0.01~0.1 s^(-1)和1150~1200℃。

The hot deformation behaviors of P550 steel for drill collars was studied through hot compression experiments using THERMECMASTOR-Z thermal simulator experimental machine at temperature of 900-1200℃and strain rate of 0.01-10 s^(-1).By analyzing the true stress-true strain curves,the constitutive equation under peak stress was established,and the effect of deformation on stress was considered,and the constitutive equation after strain compensation optimization was established.The research results show that the flow stress of P550 steel decreases with the increase of deformation temperature and the decrease of strain rate.Moreover,this constitutive equation has high prediction accuracy,with correlation coefficient and average relative absolute error of 0.99%and 6.70%,respectively,and the absolute error within 20 MPa is 91.05%of the data,thus the accuracy and guidance of the model are verified.In addition,the hot possessing maps of P550 steel were constructed based on dynamic material model,and combining with microstructure analysis,it is found that no recrystallization occurs at 900℃.As the temperature increases,the degree of recrystallization significantly increases.The optimal hot processing parameters are obtained:0.01-0.1 s^(-1) and 1150-1200℃.