回火温度对40CrNiMo调质钢CMT堆焊HAZ组织性能的影响

针对海洋钻井平台齿轮的修复问题,采用冷金属过渡(CMT)技术在40CrNiMo调质钢表面进行堆焊,利用扫描电镜、显微硬度测试、冲击性能测试和拉伸性能测试等手段,研究了焊后回火温度对40CrNiMo调质钢堆焊热影响区(HAZ)组织和性能的影响。结果表明:随着焊后回火温度的升高,焊接热影响区的硬度逐渐下降,堆焊试样的抗拉强度逐渐下降,伸长率逐渐提高。焊后回火温度为400 ℃和500 ℃时,析出的碳化物在马氏体的条界、束界和晶界上分布,恶化了堆焊试样的冲击性能;焊后回火温度为600 ℃时,碳化物聚集长大和球化,并愈发弥散分布,从而改善了冲击性能。

Effect of tempering temperature on HAZ microstructure and properties of CMT welded 40CrNiMo quenched and tempered steel

In order to repair the marine drilling platform gear, 40CrNiMo quenched and tempered steel was surfacing welded by cold metal transfer (CMT) technology. Effects of post-welding tempering temperature on HAZ microstructure and properties of the 40CrNiMo quenched and tempered steel were investigated via the characterization methods such as scanning electron microscope (SEM), microhardness test, impact test and tensile test. The results show that with the increase of post-welding tempering temperature, both the microhardness of the HAZ and the tensile strength of the welded specimen decrease, while the elongation increases gradually. When tempered at 400 ℃ and 500 ℃, the precipitated carbides are distributed on the lath boundary, block boundary and grain boundary of martensite, which worsens the impact property of the welded specimens. When tempered at 600 ℃, the carbides are aggregated, spheroidized, and distributed more dispersedly, so that the impact property is improved.