Nb Microalloyed Modern Ferritic Stainless Steel

Abstract

Ferritic stainless steel is being paid attention by steel industry and downstream users relying on its good over-all properties and low cost. With improvement of metallurgical technology and researching on fundamental theory, further development is obtained in properties optimization and quality stabilization of modern ferritic stainless steel, its marked feature are super purification and Nb/Nb-Ti stabilization. Nowadays, modern ferritic stainless steel is used widely in auto industry, home appliances, solar water heater, construction and decoration fields. The paper focuses on the effect mechanism of Nb technology on modern ferritic stainless steel and summarizes its application progress in typical downstream industries in China. Nb in modern ferritic stainless steel improves mainly in formability, corrosion resistance, weldability, high temperature and surface qualities. Studies show Nb is one of most effective element to improve drawability of ferritic stainless steel, Nb(CN precipitation in high temperature bring the result of no solid solution C during hot rolling which is extremely beneficial for the formation of positive texture and improve the formability consequently. The effect of Nb and Ti on improving intergranular corrosion by strongly stabilization C and N. Nb show the positive effect on weldability of ferritic stainless steel by Nb C N hindering grain growing and formation of fine equiaxed crystal grain in welding HAZ, which make the possibility of Nb-bearing stainless steel application in higher requirement on weldability.