二相ステンレス鋼溶接熱影響部のじん性におよぼす再加熱の影響

概要

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Post weld heating was applied to the simulated samples of the bond region of super duplex stainless steel in order to improve the toughness of weld bond region. The heating temperatures used were 1173K, 1273K and 1373K. The morphology of the secondary austenite changed from small intragranular type to massive austenite type as the heating temperature increased. The rate of austenite formation was fastest when the heating temperature was 1273K due to the C-curve kinetics. When the heating time exceeded 120s, the austenite content reached 50% in any heating temperatures. Charpy impact tests were performed using the specimens in which austenite content reached 50%. In the case of the heating temperature of 1173K, the toughness was hardly improved probably because of the precipitation of chromium nitrides or small amount of sigma phase. When the heating temperature was 1273K, good toughness comparable to the base metal could be obtained. It was found that the massive intragranular austenite arrested the cleavage crack and formed small steps and tear ridges among the cleavage facets from the fractographic observation based on three-dimensional morphology and observation of the cross sectional microstructure of cleavage fracture surface.
社団法人日本材料学会の論文
2006-11-15