화학공학소재연구정보센터
Materials Science Forum, Vol.426-4, 1379-1384, 2003
Effect of solidification structure and thermomechanical processing on microstructure and texture of ferritic stainless steels
Because ferritic stainless steels are not subject to dynamic recrystallization, a large unrecrystallized zone is formed at strip mid-thickness after hot rolling and annealing. The difference in texture among these refractory grains produces, during deep drawing of final product, an undesired surface aspect called roping. In this paper hot rolled and annealed samples of AISI 430 ferritic stainless steel have been investigated in order to assess the effect of the initial columnar or equiaxed solidification structure on final microstructure and textural behaviour. Wedge-shaped specimens were machined from slabs with both columnar and equiaxed structure, hot rolled with various thickness reductions (30 - 75%) at different temperatures (1050degreesC-1200degreesC) and heat treated simulating industrial annealing. An attempt has been made to relate microstructural and textural properties with surface roping behaviour. Therefore, some of the samples have been subsequently cold rolled and annealed in laboratory and ranked in terms 4 roping grade by roughness measurements. Results show that the recrystallized volume fraction after hot rolling and annealing is higher in the samples with an initial equiaxed solidification structure. Poor influence of the hot rolling parameters was detected for a given solidification structure. Less susceptibility to roping has been observed on cold rolled samples from initial equiaxed solidification structure.