| 摘要 |
<p>The process, comprises subjecting a hot form at 900-1300[deg] C, and cooling in air, where an average austenite grain size after a final hot form is smaller than 50 mu m and the cooling step occurs from the hot form at resting or moving air so that the temperature of 400-600[deg] C with a cooling rate of 0.1-4.0 K/s is passed through. The steel product comprises: carbon (0.03-0.20%); manganese (2-4.%); chromium (0.05-2%); nickel (0.05-1%); phosphorus (0.035%); molybdenum (0.5%); nitrogen (0.02%); aluminum (0.04%); boron (0.005%); titanium (0.10%); silicon (0.8%); and residual iron. The process, comprises subjecting a hot form at 900-1300[deg] C, and cooling in air, where an average austenite grain size after a final hot form is smaller than 50 mu m and the cooling step occurs from the hot form at resting or moving air so that the temperature of 400-600[deg] C with a cooling rate of 0.1-4.0 K/s is passed through. The steel product comprises: carbon (0.03-0.20%); manganese (2-4.%); chromium (0.05-2%); nickel (0.05-1%); phosphorus (0.035%); molybdenum (0.5%); nitrogen (0.02%); aluminum (0.04%); boron (0.005%); titanium (0.10%); silicon (0.8%); and residual iron and/or steel impurities. A weight percentage of carbon, manganese (2.55%), chromium, nickel and molybdenum satisfies the equation as given in the specification. The steel product is formed with the structural components having lower bainite (60-95%), granular or upper bainite (10%), martensite (40%), austenite (20%), and ferrite (2%). An independent claim is included for a hot-pressed steel product.</p> |
