Effect of Ti addition on forming limit diagrams of Nb-bearing ferritic stainless steel

In order to better understand the grain size, texture evolution and forming limit major strain of ferritic stainless steel, two kinds of ultrapure ferritic stainless steels (Nb single stabilization and Nb + Ti dual stabilization) with 15 wt%Cr content of the same thickness processed by the same annealing treatment have been studied in this work. Ti addition does not improve the r-value as much, but it appears to refine the grain size of the ferrite and increase the {1 1 1}〈1 1 2〉 texture component in the γ-fiber, especially reduce the planer anisotropy value. The enhancement of the formabilities especially the drawability in forming limit diagram of Nb + Ti dual stabilization 15%Cr ferritic stainless steel mainly due to the refinement of the grain size, higher average r-value and lower planer anisotropy value.