Effect of TiN direct inoculation and hot rolling on grain refinement and mechanical properties of AISI 430 stainless steel

Abstract

AISI 430 stainless steel was mechanically improved through grain refinement and a thermomechanical process. The as-cast rectangular and cylindrical products have been fabricated by the addition of TiN inoculant by direct inoculation upon casting process followed by a hot rolling process to produce the as-rolled product which has improved mechanical properties. However, the dissolution of TiN was unavoided, the dispersion was not reached, and supported by the presence of unintended entrained oxides during the casting process, forcing TiN and Ti to be incorporated with oxides in the stainless steel matrix which resulting suboptimal grain refining effect and the terminology of direct inoculation process became irrelevant. Regardless of unintended results, recrystallization that happened to as-rolled as well as solid solution strengthening and grain boundary strengthening mechanisms contributed to the increase of the strength of as-cast and rolled products. In particular for as-rolled cylindrical that came from the as-cast product, a combination of improvement toughness and strength obtained from tensile test and which any means the two processes of casting and hot rolling have continuous benefits to improve mechanical properties.