| 摘要 |
<p>1417330 Differentially heat-treating steel wheels ITALSIDER SpA 2 March 1973 [2 March 1972] 10267/73 Headings C7A and C7N [Also in Division B3] A maroblock wheel of low alloy low carbon quenching steel is rolled, normalized, and rapidly cooled in liquid, brought to tempering temperature, and differentially tempered by cooling the tread part by a liquid while other parts are cooled in air. In an embodiment, the steel is of composition by weight C 0.25-0.35%, Mn 1.00-1.30% Cr 0.90-1.20%, Si 1.00-1.20% Mo 0.20-0.30%, the rest being iron and incidental impurities. After rolling the wheel is cooled slowly to 200‹C, heated to 880‹C and kept at that temperature for about 2 hours, and then quenched in water. It is then heated to 600‹C and kept at that temperature for 3 hours, and differentially tempered by cooling the rim in running water while leaving the remainder to cool in air, cooling taking about 10 to 15 minutes. The resulting wheel was found to have favourable residual compression stresses in the tread portion, and good values of wear, toughness, and thermal and mechanical fatigue resistance.</p> |
