| 摘要 |
The invention concerns a steel material which consists of a steel having the following chemical composition in weigh-%: 1.0-1.9 C, 0.5-2.0 Si, 0.1-1.5 Mn , 4.0-5.5 Cr, 2.5-4.0 (Mo + W/2), however max 1.0 W, 2.0-4.5 (V + Nb/2), howev er max 1.0. Nb, balance iron and impurities in normal amounts in the form of residual elements from the manufacturing of the steel, and with a microstructure, which in the hardened and tempered condition of the steel contains 5-12 vol-% MC-carbides, at least about 80 vol-% of the carbides having a size which is larger than 3 .mu.m but smaller than 25 .mu.m, preferably smaller than 20 .mu.m, and, prior to tempering, 0.50-0.70 weight- % carbon, which is dissolved in the martensite in the hardened condition of th e steel. The material is intended for cold work tools, in the first place for homogenous rolls for cold rolling of metal strips.
|
