| 摘要 |
PURPOSE:To enhance the rolling wear resistance of a pipe for a rolling-contact bearing steel by a method wherein a blank steel pipe containing C, Si, Mn, Cr, P and the like at specified ratios is subjected to softening annearling, then a cold rolling and spheroidizing of sulfides are sequentially conducted in specified conditions. CONSTITUTION:A rolling-contact bearing steel consisting of 0.80-1.20% of C, 0.05-1.50% Si, 0.20-2.00% of Mn, 0.80-2.00% of Cr, less than 0.030% of P, 0.010-0.050% of S, less than 0.0017% of O, less than 0.007% of Ti, and balance of Fe and impurities, with S/O ratio not smaller than 5, is formed into a blank steel pipe by hot rolling or hot extrusion. After subjecting the blank steel pipe to softening anneaing, the pipe is cold-rolled with a reduction of area of at least 40% and is finished to a product size, followed by heating to 800-1,200 deg.C for 3-1,000min to spheroidize the sulfides in the steel. Thereafter, annealing for spheroidizing carbides is conducted. If required, Mo can be added in an amount of 0.05-0.30%. |
