| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide medium carbon steel for a grease sealed bearing, for effective prevention of peculiar microstructural changes, by using a more inexpensive Cr-free material by means of general heat treatment. SOLUTION: A steel, having a composition consisting of, by weight, 0.4-0.7% C, 0.15-0.35% Si, 0.6-0.9% Mn, <=0.025% P, <=0.025% S, and the balance Fe with inevitable impurity components and <=10ppm oxygen, is used, and nitrogen is penetrated by >=0.2mm into the surface of at least one rolling surface by means of carbo-nitriding or nitriding treatment. It is desirable to regulate carbon potential to <=0.7% and further to regulate B content to 0.0005-0.0020wt.%.</p> |
