| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel for a machine structure, which has superior strength characteristics after a component has been worked, while keeping cold workability, and has little distribution of hardness, and further from which a large component such as a crankshaft can be manufactured; a method for manufacturing the same; and a component for the machine structure which is formed by working the steel for the machine structure. SOLUTION: The steel for the machine structure has a composition containing, by mass%, 0.005-0.045% C, 0.005-0.05% Si, 0.4-1% Mn, 0.05% or less P, 0.005-0.05% S, 0.005-0.03% Al, 0.01-0.02% N and the balance Fe with unavoidable impurities, while controlling an amount of dissolved N to 0.008 mass% or more and an amount of N in a compound state to 0.002 mass% or more; and includes a ferrite phase of which the structure fraction is 95% or more and the crystal grain has an average crystal grain size of 5-20μm and an aspect ratio of 0.5-2. COPYRIGHT: (C)2010,JPO&INPIT |
