A New Explanation for Role of Delta-Ferrite Improving Weld Solidification Crack Susceptibility in Austenitic Stainless Steel(Materials, Metallurgy, Weldability)

概要

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The reason why delta-ferrite improves the weld solidification crack susceptibility of austenitic stainless steels has been investigated, applying fractographic technique to solidification cracks induced with the Varestraint test. Then a new explanation for the beneficial effect of delta ferrite has been proposed. Main conclusions obtained are as follows: (1) Segregation of impurities during the solidification is decreased in the weld metal containing a small amount of delta-ferrite, because delta-ferrite having a greater solubility for impurities solidifies as the primary phase. (2) Propagation of solidification crack in the weld metal containing a small amount of delta-ferrite is arrested by the peritectic/eutectic reaction, because the residual liguids are confined as liquid droplets inside austenite grains formed on the occasion of this reaction. This (2) is the new explanation proposed by the authors.
大阪大学の論文