摘要
采用Gleeble-3500热模拟试验机对补焊及中间回火后15Cr1Mo1V钢补焊后焊接热影响区进行热模拟,通过金相观察、扫描电镜分析、显微硬度试验和冲击试验,研究了中间回火对长期服役的15Cr1Mo1V钢焊接热影响区显微组织和力学性能的影响。结果表明:服役态组织为铁素体+粒状贝氏体+晶内弥散碳化物+晶界链状碳化物,补焊后,回火区组织与长期服役态基本一致,不完全相变区和完全相变区的组织为铁素体+粒状贝氏体+珠光体+颗粒状晶界碳化物,但不完全相变区晶内存在弥散碳化物,粗晶区组织为板条贝氏体+少量粒状贝氏体;经中间回火后,回火区的晶界上碳化物增多,不完全相变区和完全相变区组织中析出的碳化物在晶界上不断聚集长大,而粗晶区晶界上出现大量链状碳化物。补焊后,除粗晶区硬度较高外,其余热影响区硬度与服役态相差不大,经过中间回火后,粗晶区硬度仍维持在补焊后的水平,其余热影响区的硬度均略有提升。由于不完全相变区和完全相变区存在珠光体组织,使得冲击性能较低,而回火区和粗晶区冲击性能较好,经过中间回火后,回火区和粗晶区的冲击性能下降,其他热影响区的冲击性能得到了改善。
Heat affected zone of 15Cr1Mo1V steel after repair welding and intermediate tempering was simulated by Gleeble-3500 thermal simulation testing machine.The effect of intermediate tempering on the microstructure and mechanical properties of the heat affected zone of the long-term serviced 15Cr1Mo1V steel after repair welding was studied by means of metallographic observation,scanning electron microscopy analysis,microhardness test and impact test.The results show that the microstructure of serviced state is composed of ferrite+granular bainite+intragranular dispersed carbide+grain boundary chain carbide.After repair welding,the microstructure of tempering zone is basically the same as that of long-term serviced state.The microstructure of incomplete transformation zone and complete transformation zone is ferrite+granular bainite+pearlite+granular grain boundary carbide,but there is dispersed carbide in the crystal of incomplete transformation zone.The coarse grain zone is composed of flat noodles bainite+a small amount of granular bainite.After intermediate tempering,there is an increase in carbides at the grain boundaries of the tempering zone.The carbides precipitated in the incomplete and complete phase transformation zones continuously aggregate and grow at the grain boundaries,while a large number of chain like carbides appear at the grain boundaries of the coarse grain zone.After repair welding,except for the high hardness of the coarse grain zone,the hardness level of the other heat affected zones is not significantly different from the serviced state.After intermediate tempering,the hardness value of the coarse grain zone remains at the level after repair welding,and the hardness of the other heat affected zones has slightly increased.Due to the presence of pearlite structure in the incomplete and complete phase transformation zones,the impact property is lower,while the impact property of the tempered zone and coarse grain zone is better.After intermediate tempering,the impact property of the tempered zone and coarse grain zone decreases,while the impact property of other heat affected zones is improved.
作者
张正华
李霄
王艳松
肖世俊
Zhang Zhenghua;Li Xiao;Wang Yansong;Xiao Shijun(Xi'an Key Laboratory of High Performance Oil and Gas Field Materials,School of Materials Science and Engineering,Xi'an Shiyou University,Xi'an Shaanxi 710065,China;Xi'an Thermal Power Research Institute Co.,Ltd.,Xi'an Shaanxi 710054,China)
出处
《金属热处理》
CAS
CSCD
北大核心
2024年第5期140-145,共6页
Heat Treatment of Metals
基金
陕西省2021年自然科学基础研究计划(221J0-594)
西安石油大学研究生创新与实践能力培养项目(YCS23113078)。
关键词
中间回火
15Cr1Mo1V钢
焊接热影响区
组织
性能
intermediate tempering
15Cr1Mo1V steel
welding heat affected zone
microstructure
properties
