Influence of C, N and Ni Contents and Temper Rolling on Intergranular Corrosion and Mechanical Properties of 17Cr-7Ni Steel

Abstract

A study has been made of the influence of C, N and Ni contents and temper rolling on intergranular corrosion and mechanical properties of a 17Cr-7Ni steel, in order to develop a high strength stainless steel with high corrosion resistance. The results obtained are as follows:
(1) Intergranular corrosion sensitivity increases with increasing C content or temper rolling reduction. (2) 0.2% proof stress of annealed materials increases with increasing (C+2N) content. Tensile stress decreases with increasing stability of austenite phase, and increases with increasing C or N content in the case of the same austenite stability. Elongation increases with increasing austenite stability.
(3) The influence of C, N and Ni contents on the tensile properties of 25% temper rolled materials is similar to that on annealed materials and 0.2% proof stress increases with (2C+N) content. (4) The strengths of austenite and martensite phase increase with increasing C or N content. The effect of C content is smaller in austenite phase and is larger in martensite phase compared with the effect of N content. (5) Tensile stress and elongation of steel with 0.2% proof stress of 780 MPa increase with increasing C and N contents and decreasing Ni content. The optimum composition of 0.02C-17Cr-6.7Ni-0.12N has been determined by the consideration of corrosion resistance and high strength.