乙二醇反应器环焊缝泄漏机理研究

Leakage Mechanism Study of Circumferential Weld in Ethylene Glycol Reactor

通过材料成分力学性能检测、表面探伤、组织观察、显微硬度测试、电子探针及能谱分析等手段,研究了乙二醇反应器环焊缝热影响区泄漏的机理。结果表明：乙二醇反应器焊接接头出现渗漏的原因是晶间腐蚀。在乙二醇反应器焊接接头热影响区不仅发现许多宏观裂纹,还发现许多微观沿晶裂纹。在裂纹处检测到碳和超量的铬,并且裂纹附近组织中晶界的显微硬度升高,间接证实了碳向晶界迁移和含铬碳化物沿晶界的析出。可通过改进焊接工艺,避免焊接时冷速过慢来防止晶间腐蚀裂纹的产生。

By means of material chemical composition and mechanical properties tests, surface inspection, microstructure observation, microhardness test, electronic probe and energy spectrum analysis, the mechanism of leakage in the heat affected zone（HAZ） of the circumferential weld of ethylene glycol reactor was studied. The results show that the cause of leakage in the welded joint of ethylene glycol reactor is intergranular corrosion. In the HAZ of the welded joint of the ethylene glycol reactor, not only many macroscopic cracks are found, but also many microscopic intergranular cracks are found. Carbon and excess chromium are detected at the crack, and the microhardness at grain boundary in the microstructure near the crack increases, which indirectly proves the migration of carbon to the grain boundary and precipitation of chromium carbides along the grain boundary. The intergranular corrosion cracking can be prevented by improving the welding process and avoiding excessively slow cooling rate during welding.