FERRITIC STAINLESS STEEL FOR AUTOMOTIVE EXHAUST SYSTEM MEMBER HAVING EXCELLENT THERMAL FATIGUE CHARACTERISTIC

摘要

PPROBLEM TO BE SOLVED: To provide a ferritic stainless steel for an automotive exhaust system member having excellent thermal fatigue characteristics. PSOLUTION: The steel contains, by mass, 0.020% C, 0.02 to 0.15% Si, 0.05 to 0.20% Mn, 0.040% P, 0.010% S, 0.05 to 0.10% Al, 0.020% N, 15 to 18% Cr, 1.5 to 2.9% Mo, 3x(C+N) to 0.25% Ti, 0.4 to 0.8% Nb, 0.003 to 0.8% Nb, and 0.003 to 0.0050% B, wherein C and N satisfy the relation of 0.030% C+N; further, Al, Si and Mn satisfy the relation 0.001 to 0.02% Alx(Si+Mn), and the balance Fe with inevitable impurities. Also, the 0.2% yield strength before the heat treatment in the atmosphere of 300 hours at 900C of the steel is 20 MPa, the 0.2% yield strength at 900C after the heat treatment is 15 MPa, and the difference in the 0.2% yield strengths before and after the heat treatment is 5 MPa. PCOPYRIGHT: (C)2006,JPO&NCIPI