Uddeholm Tooling Aktiebolag

Bo Rydell

Odd Sandberg

The invention concerns a steel article, which consists of an alloy having a chemical composition, which contains in weight-%: 1.2 to 2.5 C; 0.8 to 2.0 Si, which partly can be replaced by aluminium, which may exist in an amount of max 1.0%; 0.1 to 1.5 Mn; 0.5 to 1.5 Cr; 1.2 to 5.0 (V+Nb/2), however max 1.0 Nb; balance iron and impurities in normal amounts, and having a microstructure which contains 4 to 12 volume-% of MC-carbides. The steel article can be used for manufacturing of cold-work tools, particularly pilger rolls for cold rolling of tubes. The invention also relates to a method of manufacturing the article.

Steel cold work tool, its use and manufacturing

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&plus;W/2), however max 1.0 W, 2.0-4.5 (V&plus;Nb/2), however 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 &mgr;m but smaller than 25 &mgr;m preferably smaller than 20 &mgr;m, and, prior to tempering, 0.50-0.70 weight-% carbon, which is dissolved in the martensite in the hardened condition of the steel. The material is intended for cold work tools, in the first place for homogenous rolls for cold rolling of meta, strips.

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Eskilstuna, Sweden

Bo Rydell