Nb-Ti微合金EH36海工钢中复合析出相沉淀析出行为研究

Precipitation behavior of composite precipitates in Nb-Ti micro-alloy EH36 offshore steel

基于EH36海工钢屈服强度影响因素的主成分回归分析,结合复合析出相固溶析出计算和经典析出动力学理论,系统研究了影响EH36海工钢屈服强度的主要因素和复合析出相的析出行为,并探讨了轧制过程奥氏体形变储能对复合析出相析出动力学的影响。结果表明,影响EH36海工钢屈服强度的主要因素为Ti、Nb和N。MN和M(C,N)分别在1728.5 K和1430.0 K开始析出,主要为(Ti,Nb)N和(Nb,Ti)C。在奥氏体相区,MN和M(C,N)的最大析出量分别为0.016 5%和0.027 7%,最大析出体积分数分别为0.000 228%和0.000 389%,发生晶界形核的最快沉淀析出温度分别为1 580.3 K和1 228.3 K。随着奥氏体形变储能的增加,MN和M(C,N)相对形核率呈增加趋势,析出孕育期明显缩短且沉淀强化作用增强。

Based on the principal component regression analysis of the factors affecting the yield strength of EH36 offshore steel,combined with the solid solution precipitation calculation of composite precipitation phase and the classical precipitation kinetics theory,the main factors affecting the yield strength of EH36 offshore steel and the precipitation behavior of composite precipitation phase inγwere systematically studied,and the influence of austenite deformation and energy storage during rolling on the precipitation kinetics of composite precipitation phase was discussed.The results show that the main factors affecting the yield strength of EH36 offshore steel are Ti,Nb and N.MN and M(C,N)began to precipitate at 1728.5 K and 1430.0 K,respectively,and were mainly(Ti,Nb)N and(Nb,Ti)C.In the austenite phase region,the maximum precipitation amounts of MN and M(C,N)are 0.0165%and 0.0277%respectively,and the maximum precipitation volume fractions are 0.000228%and 0.000389%respectively.The fastest precipitation temperatures for grain boundary nucleation are 1580.3 K and 1228.3 K respectively.With the increase of deformation energy storage,the relative nucleation rate of MN and M(C,N)increases,the incubation period of precipitation is obviously shortened and the precipitation strengthening effect is enhanced.