What is the common quality problems of bearing parts?

What are the common quality defects in the high temperature bearing part? High temperature bearing to make the heat treated parts ( 处理) The quality control of common defects are: after quenching microstructure in the process of organizational development is overheating, less heat, quenching crack is studied, hardness is not enough, deformation, heat treatment and appearance decarburization ( C) , soft point etc. 1. Quenching crack due to stress during the process of high temperature quenching crack of bearing parts described in the quenching crack. The causes of crack formation: due to the quenching temperature ( Temperature) Too high or too fast cooling, when stress and thermal stress of the metal quality than the breaking strength of the steel volume change is bigger; The original appearance defects ( For example, the appearance of fine after quenching; Crack or scratch) Internal defects (or steel For example, slag, serious non-metallic inclusions, white spots, the rest of the shrinkage rate, etc. ) Consisting of stress concentration in the quenching; Unsmiling carbide segregation and decarburization or lack of tempering tempering time; Stress of the cold forming steps is too big, folded forging, turning dark mark, such as tank sharp edges. In short, the reason quenching crack can be one or more of these components, the main reason is the internal stress configuration quenching crack. Quenching crack deep and long, straight fracture, no oxidation color fracture. It is in the high temperature bearing ring is usually a longitudinal or annular flat crack crack; Appearance of high temperature ball bearing is S shape, T shape or ring. Organization decarburization on the quenching crack phenomenon on both sides of the crack, significant differences ( Material) Forging cracks and crack and information. 2. Overheating from high temperature bearing parts on the rough surface can see to the microstructure of different quenching after organization development overheating, but the exact judging its overheating level to provide necessary view microscopic technology organization. If in gcr15 steel quenching can organize appears coarse acicular martensite, economic organization for quenching overheating. Constitute a reason and possible ( 也许) Is quenching heating temperature, through high or heat insulation work time cannot too long did not form the comprehensive construction of overheating; May also be due to the primitive society organizations banded carbide, there are serious in low carbon (between the two belts 低碳) Area constitute the main part of the martensite acicular bulky, forming part of the market is overheating. Overheating protection group increased, the retained austenite content in land size of relative stability. Overheating due to quenching organization, steel crystal bulky, toughness landing will incur parts, shock resistance, decrease of high temperature bearing's life also reduced. Overheating phenomenon is a serious problem that will form the quenching crack. 3. Heat treatment ( Processing) High temperature deformation of bearing ( Bearing) Components in the thermal stress and organization stress exist in the process of heat treatment. Stresses in the stacks or partially offset, this is complicated and changeful, because it can heating temperature, heating rate, cooling, cooling speed, the change of the part shape and size, so the heat treatment deformation is inevitable. To understand and control the change rhythm ( Rhythm) Help to the high temperature deformation of the bearing parts, Such as ovality of ring, the increase of size, etc. ) Control in a controllable scope, help prevent consumption. The mechanical shock in the process of heat treatment, of course, also can make the part deformation, but by improving operation can reduce and prevent the deformation. 4. A: bearing steel application scope and technical standard: next article no