Evaluation of the stress-strain state in alloy 718 after hydrogen charging

Abstract

The changes in the stress-strain state as a result of hydrogen saturation of Alloy 718 produced via traditional and 3D metal printing routes were studied. The stress-strain state of the material after electrochemical hydrogen charging was measured by X-ray technique using diffractometers with two power levels to obtain the information from different depths from the surface. It was found that most of the hydrogen accumulated in the thin surface layer. It was found that the microstrains and sub-microstrains changed up to 35% in a depth of ~5–30 μm as a result of the electrochemical hydrogen charging. The changes in the residual stress (macrostress) as a result of cathodic charging were not detected in the studied materials. As a result of hydrogen desorption at 200–800 °C, the stress-strain state of the investigated alloy returned to its initial state for traditionally made material. The bulk of hydrogen after cathodic charging was removed by heating to 300 °C.