High temperature ductility and corrosion resistance property of novel tin-bearing economic 17Cr–xSn ferritic stainless steel

Abstract

A new family of resource-saving ferritic stainless steels, with the composition of 17Cr–xSn (x = 0.1–0.4 wt-%) have been developed by examining the effect of Sn on high temperature ductility, the corrosion resistance properties and the passivation film structure. The results show that tin-bearing stainless steel obtains superb plasticity and there is no evidence of tin-containing precipitation in the fracture facets. High temperature brittleness at about 900°C is caused by the carbide or nitride precipitation along the grain boundary or inside. The precipitation in the grain boundary hinders the free movement of dislocation, thus increasing the strength and decreasing the toughness of steel. The polarisation curves and weight loss measurement indicate that the corrosion resistance of stainless steel is improved by adding small amount of Sn. The existence of Sn in passivation film suppresses the anodic dissolution of steels during long exposure to the aggressive solution, and the dense rust layer is thick enough to protect the steel and strongly inhabit the ingress of the solution.