| ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ KAWASAKI STEEL TECHNICAL REPORT No.42 ( May 2000 ) ‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘‘ |
| TS 780 MPa Grade Hot Rolled Sheet Steel with
High Fatigue Strength Tetsuo Shimizu, Nobuo Aoyagi |
| Synopsis: The effect of microstructure on fatigue strength has been investigated to develop 780 MPa TS grade high strength hot-rolled sheet steels applicable to automotive wheels and chassis. Even if the second phase was beinite-martensite or pearlite, precipitation strengthening of ferrite matrix suppressed initiation of fatigue cracks, and exhibited an increase in fatigue limit. The second hard phase of martensite suppressed fatigue crack propagations and exhibited a significant increase in fatigue strength. As a result, 780 MPa TS grade steel with high fatigue strength, excellent tensile strength-elongation balance and high hole expanding ratio can be developed. The newly developed steel was applied to automotive high strength and lightweight wheels for the first time in the world. |
| TextiPDF: 5P/313kbj |