WEAR RESISTANT COLD WORK TOOL STEEL HAVING HIGH IMPACT TOUGHNESS, MADE BY POWDER METALLURGY AND A METHOD FOR PRODUCING THE SAME

摘要

The abrasion-resistant, high-impact, nitrogen-sprayed pre-alloy powder powder produced by powder metallurgy of the present invention contains vanadium-rich carbides, and has a weight percent composition of: carbon 0.6-0.95 manganese 0.1-2 phosphorus up to 0.1 sulfur maximum 0.15 silicon up to 2 chromium 6 to 9 molybdenum up to 3 tungsten up to 1 vanadium 2 to 3,2 nitrogen up to 0.15, and iron and standard impurities in the remainder where maximum carbon content (% C) maximum = 0.60 + 0.177 (% V-1, 0) and the hardness of the steel in hardened and tempered state is at least 58 HRC, with 4 to 8% by volume of dispersion carbide, where carbides are MC type carbides with a maximum size of up to 6? and tool steel Charpy Cranking is greater than 660 joules. The steel is made by the following steps: the die steel melt is sprayed with nitrogen gas at a temperature of 1535 to 1650 ° C, the resulting powder is cooled to room temperature and classified into a 16 mesh isostatic hot press at a pressure of 1090 to 1120 ° C at a pressure of 91 to 112 × 104 Pa. and exercise, until a hardness of at least 58HRC is achieved, and then 4 to 8% by volume of vanadium-rich MC type carbides with a maximum size of primary carbides of up to 6? and the tool steel Charpy C has at least 660 joules. ŕ