An Investigation of Friction Coefficient on Microstructure and Texture Evolution of Interstitial-Free Steel during Warm Rolling and Subsequent Annealing

A Ti bearing interstitial-free steel was finishing rolled in the ferrite region with and without lubrication and microstructures, mechanical properties and textures evolution during warm rolling and subsequent annealing were investigated by OM, SEM, tensile test and ODF. The results show that the surface microstructure of the as-rolled specimen without lubrication is composed of dense shear bands, while the microstructures of the central layer of the as-rolled specimen without lubrication and the whole cross section of the as-rolled specimen with lubrication are elongated ferrite. Short-time annealing can make the non-lubricated rolling sample recrystallize, but the lubricated rolling sample cannot. After complete recrystallization, the microstructure of the surface layer of the as-annealed specimen without lubrication is finer than that of the center layer of the as-annealed specimen without lubrication and the whole section of the as-annealed specimen with lubrication. The mechanical properties of as-annealed sample without lubrication change significantly in the initial annealing stage, while that of as-annealed sample with lubrication remain unchanged until the end stage of annealing. The surface layers of the as-rolled samples have strong Goss component and weak gamma fibre components, while the central layers have strong gamma fibre components and moderate rotated cubic components. As annealing proceeds, the Goss components of the surface layer decrease and the gamma fibre components increase. The rotated cubic components in the central layer are gradually transformed into gamma texture.