STEEL FOR MACHINE STRUCTURAL USE

文件类型：PDF文档
文件大小：272K
PROBLEM TO BE SOLVED : To provide inexpensive steel for machine structural use which does not substantially comprise Pb and has excellent machinability, and in which the anisotropy of mechanical properties is reduced. SOLUTION : The steel for machine structural use has a chemical composition comprising 0.1 to 0.6% C, 0.03 to 2.0% Si, 0.2 to 2.0% Mn, 0.03 to 0.20% S, ≤0.1% P, 0.001 to 0.02% N, 0.0003 to 0.005% Al, 0.0001 to 0.01% Ca, 0.0005 to 0.005% O, and 0.0001 to 0.01% Te, and the balance Fe with impurities, and in which the content of Mg in the impurities is controlled to ≤0.001%, and comprises MnS-based inclusions including 0.1 to 0.6 atomic% Te and having a shape in which the width W is ≥2μm, and also, the ratio between the length L and the width W, L/W is ≤5 in the longitudinally vertical section. The steel can further comprise one or more kinds of metals selected from Ti, Cr, V, Mo, Nb, Cu, and Ni or/and one or more kinds of metals selected from Bi and REMs (rare earth metals).