To provide a hot-working tool steel which has improved toughness and high-temperature strength, and to provide a production method therefor.
The hot-working tool steel comprises, by mass%, 0.34 to 0.40% C, 0.3 to 0.5% Si, 0.45 to 0.75% Mn, 0 to less than 0.5% Ni, 4.9 to 5.5% Cr, Mo and/or W singly or totally in an amount of 2.5 to 2.9% in (Mo+1/2W) terms, 0.5 to 0.7% V, and the balance Fe with unavoidable impurities; and has a cross-sectional structure containing a bulk structure and a needle-like structure after having been quenched, in which the bulk structure (A%) shares 45 area% or less, the needle-like structure (B%) shares 40 area% or less, and remaining austenite (C%) shares 5 to 20 volume%. The method for producing the hot-working tool steel includes tempering the above hot-working tool steel so that a value X of the relationship between tempered hardness (HRC) and a structure ratio can be 40 or more, which is expressed by the following expression: X=[-0.36(HRC)-1.47(A%)-1.67(B%)+6.55(C%)+72.91].
NAKATSU EIJI
TAMURA ISAO
NAGASAWA MASAYUKI
| JPH02179848A | 1990-07-12 | |||
| JPH0260748B2 | 1990-12-18 | |||
| JPH08188852A | 1996-07-23 | |||
| JP2006104519A | 2006-04-20 |