HIGH-CARBON STEEL WHEEL BEARING AND A HEAT-TREATING METHOD THEREOF, CAPABLE OF IMPROVING TOUGHNESS AND STRENGTH ALTOGETHER BY REFINING A GRAIN WITH ADDING A SMALL AMOUNT OF NIOBIUM

摘要

PURPOSE: A high-carbon steel wheel bearing and a heat-treating method thereof are provided to improve a material and a process, thereby optimizing the contact-service life of the high-carbon steel wheel bearing component under the condition of an identical load.;CONSTITUTION: A high-carbon steel wheel bearing comprises 1.00 to 1.10 wt% of C, 0.50 to 0.70 wt% of Si, 1.00 to 1.20 wt% of Mn, 1.45 to 1.65 wt% of Cr, 0.20 to 0.40 wt% of Ni, 0.02 to 0.04 wt% of Nb, less than 0.025 wt% of P, and less than 0.008 wt% of S. The high-carbon steel wheel bearing includes an inner race, an outer race, and plural balls. The inner race is assembled to be inserted into the outer circumference of a wheel hub. The outer race is assembled to be inserted into the inner circumference surface of a knuckle. The plural balls are interposed between the inner race and the outer race for relatively rotating. The heat-treating method of the high-carbon steel wheel bearing comprises: A step of quenching a bearing-shaped steel component for 60 minutes at the temperature of 840 degrees Celsius; a step of hardening the quenched component for 30 minutes at the temperature of 780 degrees Celsius; and a step of tempering the hardened component at 60 minutes at the temperature of 175 degrees Celsius.;COPYRIGHT KIPO 2013;[Reference numerals] (AA) Quenching OIL temperature: 115°C