采用宏观观察、化学成分分析、力学性能测试、金相检验及能谱分析等方法对某余热锅炉减温器12Cr1MoVG钢喷管的开裂原因进行分析。结果表明：在减温器反复启停的过程中，流入喷管内水的温度与管体的温差较大，使喷管承受较大的交变热应力，在内、外管壁形成热疲劳裂纹，最终导致喷管发生开裂。

Macroscopic observation, chemical composition analysis, mechanical property measurement, metallographic examination and energy spectrum analysis were used to analyze the causes of 12Cr1MoVG steel nozzle cracking of desuperheater in heat recovery steam generator. The results show that in the process of repeated start-up and shutdown of the desuperheater, the temperature difference between the water flowing into the nozzle and the pipe body was large, which made the nozzle bear large alternating thermal stress and formed thermal fatigue cracks on the inner and outer pipe walls, leading to the cracking of the nozzle finally.