Cold work steel

Abstract

Abstract The invention relates to a cold work steel having a very high resistance to wear and good impact strength made powder-metallurgically through the consolidation of metal powder to a dense body. The powder has the following chemical composition expressed in weight-%: 0.5-2.5 C, 0.1-2 Si, 0.1-2 Mn, 0.5-1.5 N, max 15 Cr, preferably 6.5-111 Cr, max 4 Mo, max 1 W, 3-15 V, wherein up to half the amount of vanadium can be replaced by 1.5 times as much niobium, and part of the vanadium can be replaced by titanium at a content up to four times the content of nitrogen and the double amount of zirconium at a content up to eight times the content of nitrogen, and wherein the ratio V/(C+N) shall amount to not less than 2.5 and not more than 3.8, balance essentially only iron, impurities and accessory elements in normal quantities. The invention also relates to a method of manufacturing the steel. First there is made a steel powder having a composition as above with the exception of the nitrogen content. The nitrogen content in the powder is max 0.5%. The powder is nitrided by means of nitrogen gas in the ferritic state of the steel at a temperature between 500° and 1000° C., preferably between 650° and 850° C. during so long period of time that the nitrogen content in the steel is increased to an amount of between 0.5 and 1.5% and such that the ratio V/(C+N) will be not less than 2.5 and not more than 3.8, and thereafter the powder is consolidated to a homogeneous body with full density.

Inventors

• 👤 William Roberts
• 👤 Borje Johansson

Bibliographic Details