氢气压缩机缓冲罐热电偶接管开裂失效分析

Failure Analysis of Thermocouple Connection Cracking in Hydrogen Compressor Buffer Tank

由于承受交变压力载荷的作用,氢气缓冲罐接管易发生开裂失效导致介质泄漏。对开裂部位进行宏观观察、化学成分分析、常规拉伸试验、显微硬度测试、扫描电镜与能谱分析检测后可知,某氢气压缩机缓冲罐热电偶接管开裂是由于裂纹源位于加强筋板与接管焊缝外表面的焊趾处,并伴有夹杂、未熔合等缺陷;连接焊缝的焊缝区与热影响区中存在粗大柱状晶、魏氏体和保持马氏体位相的回火组织,提高了焊缝的淬硬性与裂纹敏感性;加强筋与接管连接焊缝结构处的应力集中程度较高,焊接残余应力以及外加交变载荷为裂纹扩展甚至开裂提供了必要条件。

Due to the alternating pressure load,the connecting pipe of the hydrogen buffer tank was prone to cracking and failure,resulting in medium leakage.After macroscopic observation,chemical composition analysis,conventional tensile testing,microhardness testing,scanning electron microscopy,and energy spectrum analysis of the cracked area,it was found that the reason for the cracking of the thermocouple connecting pipe of a hydrogen compressor buffer tank was due to the crack source located at the weld toe of the strengthening rib plate and the outer surface of the connecting pipe weld,accompanied by defects such as inclusions and lack of fusion.The presence of coarse columnar crystals,martensite,and tempered microstructure with retained martensite phases in the weld zone and heat affected zone connecting the weld seam improved the hardenability and crack sensitivity of the weld seam.The stress concentration at the welded joint structure connecting the reinforcing rib and the connecting pipe was relatively high,and the welding residual stress and external alternating load provided necessary conditions for crack propagation or even cracking.