摘要
为研究Q690桥梁钢焊接性能,应用Gleeble-3500热仿真模拟试验仪,采用膨胀法与OM组织观察和显微硬度检测相结合的方法,制作Q690桥梁试验钢的焊接热影响区(HAZ)连续冷却转变曲线(SH-CCT曲线),探讨不同冷却速度下HAZ显微镜组织和显微硬度;根据焊接热仿真模拟,分析不同焊接峰值温度对试验钢HAZ组织和物理性能产生的影响。结果表明:随冷速增大,试验钢相继发生LB+GB、LM+LB+GB相变,显微硬度逐渐增大;临界热影响区(ICHAZ)组织为铁素体和贝氏体,细晶热影响区(FGHAZ)组织为细小的板条贝氏体(LB)和少量粒状贝氏体(GB)以及板条马氏体(LM),粗晶热影响区(CGHAZ)由粗结晶体LM、少量LB和GB组成,随焊接峰值温度增高,组织逐渐粗化,显微硬度先增大后减小,-40℃冲击吸收功逐渐减小。
In order to study the welding properties of Q690 bridge steel, by combining the dilation method with OM observation and micro-hardness measurement, the continuous cooling transition curve(SH-CCT curve) of the welding heat-affected zone of the experimental steel was drawn with the Gleeble-3500 thermal simulation testing machine, the change laws of the microstructure and micro-hardness of the heat-affected zone(HAZ) at different cooling rates were studied;and the effect of the peak welding temperatures on the microstructure and mechanical properties of the experimental steel’s HAZ was studied by welding thermal simulation tests. The results show that with the increase of cooling rate, the experimental steel undergoes phase transformations of LB+GB and LM+LB+GB, and the micro-hardness gradually increases;the structure of intercritical heat-affected zone(ICHAZ) is composed of ferrite and bainite, the structure of fine-grained heat-affected zone(FGHAZ) is composed of fine lath bainite(LB), a small amount of granular bainite(GB) and lath martensite(LM), and the structure of coarse-grained heat-affected zone(CGHAZ) is composed of coarse LM and a small amount of LB and GB;as the peak welding temperature increases, the structure gradually becomes coarser, the microhardness increases first and then decreases, and the impact absorbing energy at-40 ℃ gradually decreases.
作者
王旭明
WANG Xuming(China Railway Fifth Survey and Design Institute Group Co.Ltd.,Beijing 102600,China)
出处
《铁道建筑技术》
2022年第12期30-34,共5页
Railway Construction Technology
基金
中国铁建股份有限公司科技研究开发计划项目(2020-A01)
中铁第五勘察设计院集团有限公司科研计划项目(T5Y2020-B03)。
关键词
Q690桥梁钢
焊接峰值温度
显微组织
力学性能
试验
Q690 bridge steel
peak welding temperature
microstructure
mechanical properties
test
