| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain excellent contact fatigue life strength, in steel having a specified compsn., by controlling the thickness of an imperfect quenched layer, the compressive residual stress on the surface, the valueβ' obtd. by making the X-ray diffraction half-value width dimensionless by the half-value width after the annealing of the steel, the relation between theβ' and the surface roughness, and the ratio of the residual austenite by surface hardening treatment. SOLUTION: This gear contains, by weight, 0.1 to 0.3% C, 0.01 to 0.5% Si, 0.3 to 1.5% Mn, 0.3 to 1.5% Cr, 0.01 to 0.06% S, 0.001 to 0.01% Ca and <=0.003% O, where the ratio of Ca/O is 0.5 to 3.5, and the balance Fe with inevitable impurities, in which, by surface hardening treatment of imparting working distortion to the surface after carburizing, hardening and tempering, the thickness of an imperfect quenched layer is controlled to <=15μm, the compressive residual stress on the surface to >=25 kgf/mm2, the valueβ' obtd. by making the X-ray diffraction half-value width dimensionless by the half-value width after the annealing of the steel to >=1.65, theβ' and the surface roughness Rmax 1ie in the relation in the formula, and the ratio of the residual austenite is controlled to <=10%.</p> |
