Method for martensite and bainite isothermal quenching of GCr15SiMn steel bearing ring

Abstract

The invention provides a method for martensite and bainite isothermal quenching of a GCr15SiMn steel bearing ring, and belongs to the technical field of bearing processing and manufacturing. The method comprises the steps that the GCr15SiMn steel bearing ring is first heated to 820-840 DEG C, then the GCr15SiMn steel bearing ring is placed in a nitrate solution of 50% KNO3 and 50% NaNo2 with the temperature of 220DEG C for isothermy, and the GCr15SiMn steel bearing ring can be taken out after 5 hours of isothermal time. The bearing ring treated by the process has high toughness and long fatigue life, especially for bearings working under heavy loads and impact, and the service life can be prolonged and the operation reliability can be improved.

Description

technical field [0001] The invention relates to the technical field of bearing processing and manufacturing, in particular to a method for austempering martensitic quenching of GCr15SiMn steel bearing rings. Background technique [0002] Most domestic bearings are made of GCr15 and GCr15SiMn bearing steel, using conventional martensitic quenching and tempering heat treatment process. Due to the hard and brittle martensite structure, during the heat treatment process, the surface of the bearing ring is oxidized and decarburized, and the surface tensile stress is formed after quenching. The ring cracks often occur during transportation and collision between processes, and grinding cracks are easily formed during grinding; secondly , during the use of the bearing, the impact load is large and the working conditions are harsh, and a considerable part of the inner and outer rings of the bearing are cracked and the ribs are broken; moreover, the effective wall thickness of the bea...

AI Technical Summary

Problems solved by technology

Due to the hard and brittle martensite structure, during the heating process of heat treatment, the surface of the bearing ring is oxidized and decarburized, and the surface tensile stress is formed after quenching. The ring cracks often occur during transportation and collision between processes, and grinding cracks are easily formed during grinding; secondly , during the use of the bearing, it bears a large impact load and harsh working conditions, and a considerable part of the inner and outer rings of the bearing are cracked and the ribs are broken; moreover, the effective wall thickness of the bearing ring is generally 25mm when the GCr15 steel bainite is quenched Below, if the wall thickness is above 25mm, GCr18Mo is generally used, but the material cost of GCr18Mo is much higher than that of GCr15 and GCr15SiMn, and the martensitic quenching workpiece has large deformation, high rejection rate and large grinding allowance, which causes great damage to bearing production. waste