rolling bearings early failure of the main rupture, deformation, wear corrosion and fatigue under normal conditions, the contact fatigue. The failure of the bearing parts in addition to the conditions of service, mainly due to the hardness, strength, toughness, wear resistance, corrosion resistance and stress state constraints. The main internal factors that influence this performance and state the following number.
1.1 quenched martensite steel
the original organization of the high carbon chrome steel granular pearlier in the state of quenching and tempering, quenching martensite carbon content significantly affect the mechanical properties of steel. Strength and toughness in about 0.5%, the contact fatigue life of about 0.55%, 0.42% compressive collapse of the ability to GCr15 steel quenched martensite carbon content of 0.5% to 0.56%, you can get the strongest anti-failure mechanical properties.
It should be noted that the martensite in this case is cryptocrystalline martensite; carbon content measured is the average carbon content. In fact, the carbon content of martensite in the micro-region is not uniform near the carbide around the carbon concentration is higher than the original ferrite part of away from the carbide, so they began the martensitic transformation temperature , thereby suppressing the martensite grain growth and microstructure morphology become hidden martensite. It can avoid prone to microscopic cracks in the quenching of high-carbon steel, and its sub-structure of high strength and toughness are wrong plate lath martensite. Therefore, only when high-carbon steel quenching of carbon cryptocrystalline martensite bearing parts may be given anti-failure ability of the best matrix.
1.2 Quenching of retained austenite in the steel
after normal quenching, the high carbon chromium steel containing 8% to 20% Ar (residual austenite). Of Ar bearing parts there are advantages and disadvantages, Ar content should be appropriate in order to better bring. Ar amount of quenching the austenitic condition, how much of it would affect the number of the carbon content of the quenched martensite and undisclosed carbides, difficult to correctly reflect the influence of Ar on the mechanical properties. To this end, the fixed Albright conditions, austenitic body of thermal stabilization treatment process, different Ar content after quenching and tempering GCr15 steel hardness and contact fatigue life, in this study. With the increase in austenite content, hardness and contact fatigue life increase, peak and then correspondingly lower, but the peak of the Ar content, hardness peak at around 17% Ar, and the contact fatigue life peak at around 9%. When the test load is reduced, due to Ar increase the amount of contact fatigue life is reduced. This is when the Ar small amount has little effect on strength reduction; the role of toughening is more obvious. The reason is that the load is small, Ar, a small amount of deformation has occurred, to each other. Not only reduced the stress peak and said to the deformed Ar processing to strengthen and occurrence of stress and strain-induced martensitic transformation and strengthening. However, if the load is large, Ar large plastic deformation with the base to experience the local stress concentration and cracked, so that the reduced life. It should be noted, of Ar beneficial effect must be under Ar steady state, if the spontaneous transformation to martensite, will make the steel toughness drastically reduced embitterment.



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