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采用扫描电子显微镜(SEM)、电子背散射衍射分析技术(EBSD)和透射电子显微镜(TEM)等实验手段,研究了不同淬火--回火热处理工艺制度对X80管件钢组织性能的影响.结果表明:一次930℃淬火后,随着回火温度的升高,实验钢屈服强度先升高后降低,在630℃达到最大值588MPa;抗拉强度随回火温度升高持续下降,680℃时降至630MPa.二次两相区淬火,经630℃回火后,X80管件钢有最佳的综合力学性能,-50℃冲击韧性显著提高,Ak达到210J.这是由于二次淬火温度在860℃两相区时,组织中奥氏体晶粒大幅细化,经630℃回火后,细晶马氏体组织中出现位错亚结构的回复软化、板条边界钝化和块状M-A组元分解产生的析出强化机制综合作用的结果.
The effects of different quenching-tempering heat treatment processes on the microstructure and properties of X80 tube were studied by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) : After quenching at 930 ℃, with the increase of tempering temperature, the yield strength of the experimental steel first increases and then decreases, reaches the maximum of 588MPa at 630 ℃. The tensile strength decreases with the increase of tempering temperature, To 630MPa. The second two-phase quenching, after 630 ℃ tempering, X80 pipe steel has the best comprehensive mechanical properties, -50 ℃ impact toughness increased significantly, Ak reached 210 J. This is because the secondary quenching temperature at 860 ℃ In the two-phase zone, the austenite grains in the microstructure are greatly refined. After tempering at 630 ℃, the dislocation substructure softens in the fine-grained martensite, the slab boundary passivates and the massive MA component Decomposition generated precipitation strengthening mechanism of the combined effect of the results.