ステンレス鋼オーバレイ溶接部のはく離並びに炭化物の性状

はく離抵抗性のすぐれたステンレス鋼オーパレス溶接法に関する研究(第5報)

抄録

The first layer overlay weld metal with austenitic/martensitic duplex microstructure provides the overlay welds with better resistance to the hydrogen-induced disbonding than that with the conventional austenitic microstructure containing several percents ferrite as previously reported.
The resistance to the hydrogen-induced disbonding occurring at the bond of the stainless steel overlay weld is affected by the carbide precipitated at the bond region.
Based on this consideration, the properties of the disbonding surface and the carbide precipitation of the disbonding resistant overlay weld were studied and compared with those of the conventional overlay weld.
The main results obtained in this study are as follows:
(1) The disbonding mainly occurred at the bond in the disbonding resistant overlay weld, while it occurred at coarse grain boundaries in the first layer weld metal adjacent to the bond in the conventional overlay weld.
(2) Fine M₂₃C₆ carbides precipitated in the first layer weld metal adjacent to the bond in the disbonding resistant overlay weld.
(3) Large M₂₃C₆ carbides precipitated at the coarse grain boundary in the conventional overlay weld.
(4) The amount of precipitated carbide of the disbonding resistant overlay weld was almost equal to that of the conventional overlay weld.