Relationship of Grain Size, Texture Distribution, and Mechanical Properties of 25Mn Casting Flange Blank Subjected to Hot Ring Rolling

Abstract

The hot ring rolling of centrifugal casting 25Mn flange blank was conducted for achieving the grain and texture distribution in the whole thickness. Compared to the casting one, the mechanical properties of the hot-rolled flange are improved, and the tensile and impact fracture are dominated by the mixture of quasi-cleavage and ductile fractures. The homogeneous grain distribution with 30–38 μm in diameter is presented near the outer and inner layers, and the irregular grain is observed in the center-layer closely related to the lower recrystallization degree. The finer and uniform distribution grains with low-angle grain boundaries approximately 60% are found in the surface layers, which are caused by the HRR, resulting in the generation of many sub-grains. The misorientation changes within grains in the surface layers illustrate an increment in the refined grains. The textures are characterized by the Brass-R {111} component along //ND, Goss {110} , and Copper {112} components, which result in the excellent tensile and yield strengths but a relative low plasticity and toughness. Thus, it is feasible to fabricate 25Mn flange with sound microstructure and excellent mechanical properties hot-rolled directly from a centrifugal casting blank by controlling texture component along RD.