As fine cracks occurred in the welded part of a compressor member (JIS-SUS630/ H1075) during the manufacturing phase, a series of test inspections were conducted. As the inspection results suggested that the cracks were most likely to have been caused by hydrogen embrittlement (HE), a bending test was carried out to reproduce these cracks after a small-sized specimen was subjected to TIG welding and post-heat treatment, then charged with hydrogen.
During the bending test, small cracks occurred in the welded part and HAZ of the specimen, and these cracks were transgranular just like the ones in the compressor member. The fracture surface of the cracks was dominated by brittle fracture, thus it is presumed that the fracture surface was generated by HE. Post-heat treatment is an effective measure to prevent cracking, and it is considered that storage times from welding to post-heat treatment and the thickness of compressor components must have affected the occurrence of cracks.
