METHOD FOR HEAT TREATMENT OF CATERPILLAR BUSH

PURPOSE:To prevent the deterioration of wear resistance, fatigue strength and toughness by executing high frequency induction heating to a caterpillar bush composing of middle carbon low alloy steel only from the outer circumferential face, making the inner circumferential face the specific temp., and cooling and tempering after quenching whole the thickness. CONSTITUTION:The high frequency induction heating is executed only to the outer circumferential surface of cylindrical body for the caterpillar bush composing of the middle carbon low alloy steel and the temp. of inner circumferential face is made to just above the Ac3 point. Just after this heating, by cooling only from the outer circumferential surface, quenching is carried out over the entire thickness, and the original austenite crystal grain near the inner circumferential surface is refined. Next, in the heating furnace or by the high frequency induction heating, the tempering treatment is executed at about 150-250 deg.C. By this method, the man-hours for heat treatment is reduced. Further, whole thickness is suitable hardened, and the inner and outer circumferential surfaces are improved and also the titled bush of improved fatigue strength and toughness is obtd.