High-hardness, high-toughness steels and crawler components, earth wear resistant components, fastening bolts, high-toughness gears, high-toughness, high contact pressure resistance gears, and wear resistant steel plates using the same

摘要

In order to provide a high-hardness, high-toughness steel, Si, Al, Cr, Mo, V, W, Ni, and Co are more appropriately added so that the steel can have an HRC hardness of 50 or higher and a Charpy impact value of 5 kgf m/cm<2 >or more by tempering at a high temperature of 600° C. or higher. The steel is a martensite steel containing at least C: 0.15 to 1.2% by weight and Si: 0.05 to 1.8% by weight, wherein Si is partially replaced by 0.15 to 1.6% by weight of Al. The steel further contains Ni: 0.3 to 2.5% by weight; Cr: 0.1 to 3.5% by weight; Mo: 0.1 to 1.7% by weight, wherein the amount of Mo is not more than the upper limit determined by the relation formula: Mo(% by weight)=1.7-0.5x(Si(% by weight)+Al(% by weight)); one or both of V: 0.05 to 0.40% by weight and W: 0.1 to 1.0% by weight; at least one alloying element of Mn, Co, Cu, Ti, B, and Nb; inevitable impurities including P, S, N, and O; and the balance consisting essentially of Fe.