| 摘要 |
PCT No. PCT/SE88/00123 Sec. 371 Date Sep. 7, 1989 Sec. 102(e) Date Sep. 7, 1989 PCT Filed Mar. 11, 1988 PCT Pub. No. WO88/07093 PCT Pub. Date Sep. 22, 1988.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 DEG and 1000 DEG C., preferably between 650 DEG and 850 DEG 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. |
