摘要
对经1100℃保温1 h空冷正火和710℃回火3 h的G115钢进行了650℃持续1000、1879、5000和7288 h的蠕变试验,检测了蠕变试验后钢的硬度和显微组织。结果表明:G115钢在650℃蠕变试验0~1000 h内,硬度下降较缓慢,随着蠕变试验时间的进一步延长,硬度快速下降。正火和回火后,G115钢晶界和板条界析出了较多细小的粒状M_(23)C_(6)相,650℃蠕变试验后,晶界和板条界析出了较细小的粒状M_(23)C_(6)相和较粗大的块状Laves相,晶内析出细小的富铜相和MX相。蠕变试验0~1000 h过程中有大量相析出,并随着蠕变时间的延长而长大。蠕变试验过程中,位错密度下降,马氏体板条变宽,晶粒长大,导致蠕变试验后钢的硬度降低。在蠕变试验0~1000 h的过程中,由于有大量的相析出,钢的析出强化效果显著,部分弥补了位错强化和马氏体板条强化作用的减弱,因此硬度下降缓慢。析出相不仅影响析出强化效果,还阻碍位错密度下降和马氏体板条变宽,是影响G115钢650℃蠕变试验过程中硬度变化的关键因素。
G115 steel that has been normalized by heating at 1100℃ for 1 h and cooling in air and then tempered at 710℃ for 3 h was subjected to creep test at 650℃ for 1000,1879,5000 and 7288 h.After this,the steel was tested for hardness and microstructure.The results showed that the hardness of G115 steel decreased slowly during the creep testing at 650℃ for 0 to 1000 h,and decreased rapidly with the further extension of creep test time.After normalizing and tempering,many fine granular M_(23)C_(6) carbides precipitated at the grain boundaries and martensitic lath boundaries,and after creep testing at 650℃,fine granular M_(23)C_(6) carbides and coarser massive Laves phases precipitated at grain boundaries and martensitic lath boundaries,and fine copperrich phases and MX phases precipitated in the grain interiors.During the creep testing for 0 to 1000 h,the steel was precipitation strengthened significantly due to precipitation of a large number of phases,which partially compensated for the weakening of dislocation strengthening and martensitic lath strengthening,and the hardness decreased slowly.The precipitates not only influenced the precipitation strengthening effect but also retarded the decrease in dislocation density and widening of martensite laths and therefore was a key factor influencing change in the hardness of G115 steel during creep testing at 650℃.
作者
周任远
翟国丽
朱丽慧
柯志刚
王金磊
宋明
ZHOU Renyuan;ZHAI Guoli;ZHU Lihui;KE Zhigang;WANG Jinlei;SONG Ming(School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;Central Research Institute,Baoshan Iron&Steel Co.,Ltd.,Shanghai 201900,China;China Special Equipment Inspection and Research Institute,Beijing 100029,China)
出处
《上海金属》
CAS
2021年第4期7-12,18,共7页
Shanghai Metals
基金
国家重点研发计划(No.2016YFC0801901)。
