HYDROGEN INDUCED CRACKING DURING IMPLANT TESTING OF ALLOY STEELS

Abstract

The initiation and pro­ pagation of hydrogen induced crack­ ing in HY-80 and HY-130 steels and E10018 and E14018 weld metals were investigated with metallographic and acoustic emission techniques. The implant specimens were welded with an AX-140 electrode and a moisture enriched shielding gas to introduce hydrogen. Both unmixed zones and partially melted zones were observed near the weld interface in the HY-130 steel, and these regions were approxi­ mately equal in size to those ob­ served in the HY-80 steel. An un­ mixed zone was also observed at the weld interface between the E14018 weld deposit and an AX-140 GMA weld bead. A partially melted zone, similar to those observed in HY-80 and HY-130, was observed in the fu­ sion boundary region between two E14018 weld beads. The average hardness of the coarse grained region in the true heat-affected zone of HY-80 and HY- 130 was found to be nearly the same. Microhardness variations in the true heat-affected zone were associated with microsegregation in the form of banding. A sharp transition in micro­ hardness, observed at the weld metal interface in both HY-80 and HY-130