Fabrication of Semi-Solid Slurry for Steels and Their Rheo-Rolling Process

Abstract

Semi-solid metal forming (SSM) has been recognized as a new forming technology, which is different from the present metal forming methods. Basic research on SSM has been put into operation and a number of SSM techniques have been widely applied in industry. In the application of SSM technique, at present, it is mainly used to produce the low melting point alloys such as Al-base, Zn-base and Mg-base alloys, but the high melting point alloys, for example steels as the most widely useful metal are not extensively studied and applied. In the present work, the electromagnetic stirring method was used to prepare semi-solid slurry of spring steel–60Si2Mn and stainless steel–1Cr18Ni9Ti. At the same time, spring steel–60Si2Mn and stainless steel–1Cr18Ni9Ti were directly rolled into thick strips in the semi-solid state (Rheo-rolling). It is aimed at studying the microstructure and properties of the strips to establish the feasibility of rheo-rolling for the production of the steel strips. According to the present research work, it has been shown that rheo-rolling process combines the casting and hot rolling into a single step for near net-shape production, compared with the conventional hot-rolled metallurgical process. Besides being such a cost-effective process, rheo-rolling process possesses irregular crystal grains such as rosette-type primary crystals in the microstructures because of sufficient agitation during solidification. The overall homogenization of the macrostructures in the whole part of steel ingot can be achieved.