| 摘要 |
To exactly obtain the steel sheet whose tensile strength is enhanced without the substantial change of toughness and whose properties are scarcely changed along its thickness, by rolling high-tensile strength steel in the gamma zone and then in the zone of warm ferrite with specified reduction ratio without reducing it in the alpha+gamma dual phase zone. ! In obtaining nontempered steel by heating and rolling the cast piece of carbon steel or low-alloyed steel or a steel piece, the cast or steel piece is rolled in an austenitic zone and then cooled down to a ferritic zone without rolling it in the dual phase zone of austenite and ferrite. Thereafter, the cast or steel piece is slightly rolled at 600W300� C with reduction ratio R(%) satisfying the formula (T is temp. in � C). ! (C)1983,JPO&Japio |
