焊接热循环峰值温度及冷却速率对SA508-3钢粗晶区组织和性能的影响
Effect of peak temperature and cooling rate in welding thermal cycle on microstructure and properties of CGHAZ inSA508-3 steel
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摘要: 针对核电设备用SA508-3钢粗晶区,采用热模拟技术研究了在不预热前提下二次焊接热循环峰值温度及冷却速率对粗晶区组织和性能的影响.结果表明,粗晶区在经历不同峰值温度及冷却速率的焊接热循环后,其显微硬度与冲击韧性起伏较大,是SA508-3钢焊接接头中性能极不稳定的区域.粗晶区在经历峰值温度600~700℃的二次焊接热循环后可以获得较好的强韧性匹配.t8/5为10 s时,粗晶区在经历峰值温度750~950℃的二次焊接热循环后,在晶界附近形成的隐晶马氏体以及晶粒的进一步粗化,使得综合性能最差,应加以避免.Abstract: Because the microhardness and absorbed energy change greatly after CGHAZ experienceing different peak temperature and cooling rate in welding thermal cycle, the CGHAZ in the SA508-3 steel joint is highly unstable. When the peak temperature in the second welding thermal cycle was 600-700℃, the CGHAZ could get a better match between hardness and toughness. The formation of hidden martensite near grain boundary and grain coarsening should be avoided after the CGHAZ experienced secondary welding thermal cycle which peak temperature was 750-950℃ and t8/5 was 10 s.
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