回火温度对ZG12Cr9Mo1Co1NiVNbNB耐热钢组织及性能的影响

Effect of Tempering Temperature on Microstructure and Properties of ZG12Cr9Mo1Co1NiVNbNB Heat Resistant Steel

为了满足高温条件下超超临界汽轮机发电机组对材料的需要,利用金相显微镜、扫描电子显微镜、拉伸试验机等设备研究了回火温度对ZG12Cr9Mo1Co1Ni VNb NB耐热钢的组织性能的影响。研究结果表明,当保持淬火温度和时间(1 100℃×1 h)不变及回火时间(2 h)恒定时,回火温度的变化对其显微组织及力学性能的影响比较明显。整体上来说,随着回火温度的上升,抗拉强度、屈服强度以及硬度,呈现先升高后降低的趋势,而延伸率则呈现先下降后上升的趋势。热处理为淬火(1 100℃×1 h)+第1次回火(730℃×2 h)+第2次回火(720℃×2 h)的试样,其显微组织相对比较理想,其板条状的回火马氏体细小致密,并且第2相呈颗粒状、大小均匀、弥散地分布于马氏体板条的晶界及晶内,因此选取其作为ZG12Cr9Mo1Co1Ni VNb NB耐热钢的优化热处理工艺。

The influence organizational performance of tempering temperature on CB2 heat resistant steel were studied by OM,SEM and other equipments. The results showed that when keeping the quenching temperature of 1 100,quenching time of 1 h and tempering time of 2 h invariant,the tempering temperature had a significant influence on microstructure and properties of CB2 heat resistant steel. With the increase of tempering temperature,the tensile strength,yield strength and hardness increased at first and then decreased. But elongation were falling before rising trend. The microstructure was ideal when heat treatment was quenching( 1 100 ℃ × 1 h) + the first tempering( 730 ℃ × 2 h) + second tempering( 720 ℃ × 2 h). Its second phase was fine and compact,grain size and granular shape,and the comprehensive mechanics performance. It was uniformly dispersed in lath martensite grain boundaries. CB2 heat steel had comprehensive mechanical properties after the heat treatment process,therefore it was chosen as the optimization of heat treatment process of CB2 heat resistant steel.