| abstract |
(57) [Summary] [Problem] Si, Al, Cr, Mo, V, W, Ni, C o with a hardness of HRC 50 or more and a Charpy impact value of 5 k To provide a high hardness and toughness steel having a g-m / cm 2 or more. SOLUTION: In a steel containing at least 0.15 to 1.2% by weight of C and 0.05 to 1.8% by weight of Si, a part of Si is 0.15 to 1.6% by weight of Al. And 0.3 to 2.5% by weight of Ni is added, and Cr is 0.1 to 3.5% by weight, and Mo is 0.1% by weight. In the range of 1 to 1.7% by weight and the formula Mo (% by weight) = 1.7−0.5 × (Si (% by weight) + Al (% by weight)) And V: 0.05 0.40% by weight, W: 0.1-1.0% by weight, or both. one or more alloying elements of u, Ti, B, Nb and P, S, This is a tempered martensitic steel containing unavoidable impurity elements such as N and O, with the balance being substantially Fe. |