某12Cr1MoVG钢锅炉高压蒸汽管道对接接头的焊缝和热影响区出现多处裂纹。采用宏观观察、化学成分分析、力学性能测试、硬度测试、金相检验及扫描电镜分析等方法，对开裂的原因进行了分析。结果表明：在焊丝材料不合格、焊接工艺参数控制不当、管道长期处于再热裂纹敏感温度区间工作和热应力等因素的综合作用下，对接接头发生了开裂。

There were many cracks in the weld and heat affected zone of the butt joint of the high pressure steam pipe of a 12Cr1MoVG steel boiler. The cracking causes were analyzed by means of macroscopic observation, chemical composition analysis, mechanical property test, hardness test, metallographic examination and scanning electron microscope analysis. The results show that the cracking of butt joint was caused by the combined action of unqualified welding wire material, improper control of welding process parameters, long-term operation of pipeline in reheat crack sensitive temperature range and thermal stress.