某集气装置原料气放空安全阀配对法兰焊口处出现裂纹, 通过宏观以及微观检验、化学成分分析、力学性能测试等方法对裂纹产生的原因进行了分析。结果表明: 该裂纹为硫化物应力腐蚀开裂所致, 焊接工艺不当或焊后冷却速度过快导致焊接接头区域出现硫化物应力腐蚀开裂敏感性组织是该焊口产生裂纹的主要原因。

Cracks have occurred in the welding joint of the flange, which is matched with a blowdown relief valve of a gas collecting device. The reason of crack was analyzed by means of macro and micro examination, chemical composition analysis, mechnical property testing and so on. The results showed that the sulfide stress corrosion cracking had occurred, and improper welding procedure or excessive cooling rate after welding was the main reason leading to the susceptive microstructure of sulfide stress corrosion cracking which resulted in the cracks in the weld.