Patent ID: 7229507
Filing Date: 2007-06-12
Classification: C21D,C22C

Abstract:
1. A high speed tool steel comprising, by mass percentage, a basic composition of: a 0.4–0.9% of C; an equal to or less than 1.0% of Si; an equal to or less than 1.0% of Mn; a 4–6% of Cr; a 1.5–6% in total of either or both of W and Mo in the form of (½W+Mo) wherein the amount of W is not more than 3%; and, a 0.5–3% in total of either or both of V and Nb in the form of (V+Nb), wherein an average grain size of precipitated carbides dispersed in the matrix of the steel is equal to or less than 0.5 μm and a dispersion density of the carbides is equal to or more than 80×10 3 particles/mm 2 , wherein the tool steel is formed by an ingot casting process.