Effect of annealing temperature on properties and second phase characteristics of 443 stainless steel hot-rolled sheets

Abstract

Commercial 0.31 wt.% Ti 443 ferritic stainless steel (FSS) hot rolled plate was selected as experiment object. Microstructures and state of the second phase of steels annealed at different temperatures from 880 to 1080 °C were researched. The tensile and impact properties were tested, the microstructure was characterized, and the fracture morphology was observed. The results indicated that annealing temperature had a significant impact on the properties and second phase characteristics of hot-rolled 443 FSS plates containing titanium. The annealed microstructure of steel exhibited a ferrite structure with bcc crystal structure. As the annealing temperature increased, both strength and elongation decreased the trends hardness and impact value showed decreased at first, then increased and decreased at last. The fracture morphology gradually transitions from ductile fracture to brittle fracture characteristics. The fracture morphology gradually transformed from ductile fracture to brittle fracture characteristics. After annealing at 980 °C, the grain recrystallization was relatively complete with uniform size and mostly presented equiaxed grains. The (110) diffraction peak were weaken. Resorption of the second phase particle caused matrix lattice distortion and induced dislocation entanglement and blockage. The second phase particles determined by SEM-EDS were TiN and TiCN, which weakened the solid solution strengthening and increased the dispersion strengthening of the steels.