焊后热处理对T23钢热影响粗晶区微观组织的影响

Effect of PWHT on Microstructure of Coarse-grained Heat-affected Zone of T23 Steel

采用Gleeble-3500热模拟试验机和热处理炉对T23钢进行了焊接热模拟和焊后热处理试验,并运用金相、硬度、扫描电镜试验,研究了不同的焊后热处理温度对T23钢热影响粗晶区(CGHAZ)微观组织的影响。结果表明,焊态热模拟CGHAZ组织类型主要是板条马氏体和贝氏体的混合组织,具有很高的硬度。随着热处理温度的提高,CGHAZ晶粒趋于细化,硬度逐渐降低。但在700℃下,晶界出现了微孔洞和含W碳化物,硬度剧烈升高,应避免在此温度进行热处理。最后确定T23钢合理的焊后热处理为750℃×2 h,可以获得良好的强韧性匹配。

The effects of post weld heat treatment （PWHT） time on the microstructure of the simulated coarse-grained heat-affected zone （CGHAZ） ofT23 steel were investigated by Gleeble-3500 simulation machine and heat-treatment furnace. According to the results of optical microscopy, microhardness, SEM, the as-welded microstructure of simulated CGHAZ is composed of lathe martensite and baimte with high microhardness. With the PWHT temperature increasing, the grains gradually become refined, the microhardness reduces, the toughness improves. But at the 700℃, micro-holes and W-rich carbides appear in the CGHAZ grain boundaries, which can deteriorate the properties of CGHAZ. At last, the most appropriate PWHT is 750℃×2 h.