ステンレス鋼のレーザ表面改質に関する研究 （第６報） 耐食性に及ぼすレーザ急冷凝固処理の影響

Abstract

In the previous report, it was shown that the massively solidified structure and the rod-like eutectic structure formed when stainless steels of a certain composition range have been rapidly solidified using laser surface melting technique. It was also found by the formation of these structures a homogenization of element distribution and refinement of structure could be obtained. In the present study, the corrosion resistance of stainless steels with the massively solidified structure and the rod-like eutectic structure which was formed by laser surface melting was investigated. Corrosion resistance was evaluated by the passivation current density (Icrit) and Piitting potential (V'C100). It was found that the corrosion resistance of stainless steels was markedly improved by formation of massively solidified structure or the rod-like eutectic structure. SEM observation revealed that such improvement was considered to be attributed to the alleviation of the solidification segregation and refinement of structure in the massively solidified structure, and to be mainly attributed to the increase of interface area due to formation of fine two-phase structure in the rod-like eutectic structure.