| 摘要 |
<p>PURPOSE:To carry out prehardening into medium hardness and to manufacture a free-cutting die steel excellent in impact resistance and toughness and easily machined into complicated shapes by adding free-cutting components, such as S and Te, to a low alloy steel with a specific composition and then applying heat treatment to the above. CONSTITUTION:As a die steel used for drawing die, metal mold for die casting, etc., 0.3-1.5%, by weight, Ni or 0.1-2.0%, in total, of at least two kinds among 0.05-0.5% V, 0.3-1.5% Al, 0.1-1.0% Nb, 0.05-1.0% Zr, and 0.05-0.5% Ti are independently or combinedly added, if necessary, to a low alloy steel which has a composition containing, as principal components, 0.2-0.8% C, 0.1-1.5% Si, 0.4-1.5% Mn, 1.0-6.0% Cr, 0.1-1.0% Mo, and 0.02-0.3% N and also containing, as free-cutting components, 0.05-0.3% S and 0.03-0.3% Te. This alloy steel is heat treated so as to be formed into a preharden steel having a medium hardness of 40-47 hardness HRC, by which a free-cutting die steel stock excellent in machinability, impact resistance, and toughness and extremely easily machined into complicated shapes can be obtained.</p> |
