After heat treatment of the common quality defects of bearing components are: quenching microstructure of heat, due to the heat and hardness of quenching cracks, deformation, heat treatment, surface removal, and soft enough.
1. heat {TodayHot}
From the roughness of bearing components can be observed after quenching on microstructure of overheating. To determine its degree must be exactly observed microstructure. If quenching of steel GCr15 organization appears in the needle-like martensite, to quench hot organization. Causes may be hardening heating temperature too high or takes too long to heat insulation result of comprehensive thermal; serious Ribbon carbide may also be caused by the original organization, in between two large low-carbon local Markov body acupuncture-like area, causing local overheating. Overheating in the organization increased residual austenite, dimensional stability decline. Overheating due to quenching organizations, large crystals of steel, will lead to a decline in parts of toughness, resistance to impact performance, and also reduce bearing life. Overheating caused by serious or even quenching crack.
2. less heat
Quenching temperature is low or bad cooling on microstructure of exceeding standard in supporting tissue, called due to the heat organization, it bring down the hardness, wear resistance sharply lower, influencing bearing life.
3. quenching crack
Bearing parts in the quenching process by forming internal stress cracking of quenching crack. Caused this crack of causes has: due to quenching heating temperature high or cooling too anxious, hot stress and metal quality volume changes Shi of organization stress is greater than steel of anti-fracture strength; work surface of original defects (as surface micro-crack or are trace) or steel internal defects (as clip slag, and serious of non-metallic clip debris, and white, and shrinkage residual,) in quenching Shi formed stress set; serious of surface de carbon and carbide partial on the; parts quenching Hou tempered insufficient or is not timely tempered; front process caused of cold rushed stress had large, and Forging fold, scar, oil trenches deep turning sharp corners, and so on. In short, may be cause of quenching crack of one or more of the above factors, there is the formation of quenching crack of main causes of stress. Quenching crack of deep and long, straight fracture, Fracture surface oxide-free color. It is often straight longitudinal cracks on the bearing ring or annular cracks; in the shape of bearing steel ball is s-shaped, t-shaped or ring-shaped. Characteristics of quenching crack is cracked on both sides without removal, distinct and forging materials for cracks and crack.
4. heat treatment deformation
When in heat treatment of bearing parts, heat stress, and stress, stress each other within this overlay or partially offset, is complex and ever-changing, as it can with the heating temperature, speed of heating, cooling, cooling rate, part shape and size change, so heat treatment distortion is inevitable. Understanding and mastering its variation of deformation of bearing components (such as the oval ring, size up) under the control of the scope, in favour of the production. Course in the heat treatment process of mechanical collision causes the deformation of parts, but this kind of distortion can be reduced with improved operations and avoid.
5. surface decarburization
During heat treatment of bearing parts, if it is heating in oxidizing medium, surface oxidation occurs so that the part surface mass fraction of carbon reduction, caused by surface decarburization. Surface decarburization layer deeper than the last processing allowance would make parts of scrap. Surface decarburization layer in metallographic test for determination of metallographic method and micro-hardness method available. Microhardness distribution measurement method for surface layer, may make the quorum criteria. {HotTag}
  6. soft point
Due to the lack of heating, cooling, and quenching caused by improper operation of bearing parts local hardness on the surface phenomenon called quenching soft enough. Like surface decarburization, it can result in surface abrasion resistance and fatigue strength of serious decline.



Other News:
Bearing parts heat treatment
Imported bearings manufactured with the holes honing head
Chongqing iron and steel into the reorganization of assets was not built before
Limbaugh, Morrissey, Perry: The dumbest political quotes of the week
Judgment of the bearing
Fluoro dwindling demand, production has risen in the circle.＂
IKO pole end knuckle bearing 1 PHS4
Bearing processing heat treatment process and technical application effect