Effect of Hydrogen on Mechanical Properties of EB-Welded Joints of JBK-75 Steel from Ambient to Cryogenic Temperatures
The method of vacuum electron-beam (EB) welding was used to butt-weld the solution-treated plates of JBK-75, an age-hardenable austenitic stainless steel. The un-notched, notched tensile specimens and Charpy impact specimens, taken from the welded plates and subjected to different aging treatments were thermally hydrogen charged under high pressure and then tested at temperatures ranging from 293 to 77 K. The effects of hydrogen charging on the mechanical properties of EB-welded joints were investigated. Hydrogen caused a small increase in the cryogenic tensile strength of the joints and some decrease in ductility, which varied with temperature. Hydrogen decreased the notched tensile strength and Charpy impact toughness of the joints. At 193 K, a minimal tendency toward hydrogen embrittlement (HE) was found for the welded joints. Overaged treatment tends to increase the HE of the joints, which is mainly associated with the precipitation of the η phase in weld metal.
KeywordsFracture Toughness Weld Metal Hydrogen Embrittlement Charpy Impact Notch Sensitivity
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