Investigation of Hydrogen Embrittlement Effects Using Ex-Situ Impact and In-Situ Slow-Rate Charpy Tests of an X65 Steel and Weld

The HE effects on notch toughness propertiesIn-situ hydrogen charging of an X65 pipeline steelX65 pipeline steel (BM) and seam weldSeam weld (WM) have been investigated using Charpy impact tests with ex-situ hydrogenHydrogen pre-charging, and slow-rate three-point bend testsThree-point bend test with in-situ hydrogenHydrogen charging. HydrogenHydrogen was introduced into the steel using an electrochemical charging method and the total hydrogenHydrogen content was estimated using LECO analysis. Although the HE effect on ex-situ Charpy impact toughness was small or negligible, the in-situ slow-rate tests showed significant HE, which increased with decreasing loading rate. The BM had higher toughness but greater HE susceptibility at slow loading rate than the WM for the X65 pipe. The results demonstrated that (i) the Charpy testCharpy test is ineffective for qualifying HE of steels and welds, and (ii) the three-point bend test at a slow deformation rate with in-situ hydrogenHydrogen charging is an effective method to examine the hydrogenHydrogen effects on the fracture properties.