| 摘要 |
<p>A novel high strength steel especially adapted for automotive applications and the like is provided by cold rolling a low carbon aluminum-killed steel containing added phosphorus and silicon as ferrite strengtheners, continuously heating the cold rolled strip to an inter-critical temperature such that from about 5% to about 25% austenite is present, water quenching to obtain a dual phase ferrite-martensite microstructure having an average volume fraction of martensite of from about 5% to about 25%, and reheating to a sub-critical temperature to temper the steel. The resultant steel has good formability as evidenced by a minimum total elongation of 18%, is free from ductility loss due to room temperature aging, and after stamping followed by a typical paint bake cycle the formed part has a minimum yield strength of 550 MPa (80 ksi). </p> |
