Date: 2013-08-20

The impact of the cylindrical roller bearing life factors and control methods

Early failure in the form of rolling bearings, main has broken, plastic deformation, wear, corrosion, and fatigue, contact fatigue under normal conditions. Cylindrical roller bearing failure of parts in addition to the conditions of service, mainly steel hardness, strength, toughness, wear resistance, corrosion resistance, and within the state of stress constraints. There are several key internal factors that affect the performance and status:
1, hardened steel martensite
Granular pearlite original organization of high-carbon chromium steel, quenching and tempering state quenched martensite carbon content significantly affect the mechanical properties of the steel. Strength, toughness and contact fatigue life of about 0.55%, the crush capacity of about 0.42%, when the the GCr15 steel quenched martensite carbon content of 0.5% to 0.56%, can be resistant to the most failure capacity of about 0.5% mechanical properties.
2, hardened steel, the residual austenite
Of high-carbon chromium steel after normal after quenching, and may contain 8% ~ 20% Ar (residual austenite). Cylindrical roller bearing parts Ar has advantages and disadvantages, Ar content should be appropriate, in order to better bring. As the amount of Ar austenitizing and quenching conditions, how much it will affect the of quenched martensite carbon content, and the number of undissolved carbides, more difficult to correctly reflect the amount of Ar mechanical properties.
Fixed Albright conditions, the use of austenitic body of thermal stabilization treatment process, to get a different amount of Ar, Ar content after quenching and tempering of GCr15 steel hardness and contact fatigue life in this study. Austenite content, hardness, and contact fatigue life increases, reaches a peak and then the attendant reduction, but the peak of the Ar content, hardness peak appeared in about 17% Ar, and contact fatigue life peak around 9%.
3, hardened steel undissolved carbides
Number of the undissolved carbides of hardened steel, morphology, size distribution, not only by the chemical composition of the steel and the impact of the original tissue before hardening, and by austenitizing conditions, the undissolved carbides cylindrical roller bearing life less impact studies. Carbide is a hard and brittle phase addition to the benefit of wear resistance, bearing due to be (in particular, non-spherical carbide) matrix cracks caused by stress concentration, which will reduce the toughness and fatigue resistance. Quenching undissolved carbides in addition to its own impact on the performance of steel, but also affect the quenched martensite carbon content and Ar content and distribution, and thus additional impact on the performance of steel.
Therefore, the quenching of undissolved carbides too much steel mechanical properties and failure resistance is harmful. Appropriate to reduce the cylindrical roller bearing steel carbon content one way is to increase the service life of parts.
Quenching of undissolved carbides in addition to the number of affect material properties, size, morphology, distribution also have an impact on the material properties. In order to avoid the cylindrical roller the undissolved carbides hazards bearing steel, the undissolved carbides (a small number), small (small size), uniform (the size of each other the difference is small and evenly distributed), round (each and carbonation The objects were highly spherical). It should be noted that a small amount of undissolved carbides cylindrical roller bearing steel after quenching is necessary, not only to maintain sufficient resistance to abrasion, but also a prerequisite for fine grain implicit martensite.
4, the residual stresses after quenching and tempering
Cylindrical roller bearing parts after quenching and tempering, still has a large internal stress. Part of the residual stress advantages and disadvantages of the two states. After the heat treatment of steel parts, as the surface residual stress increases, the fatigue strength of the steel along with it, the contrary, the surface residual stress is a tensile stress, so that the fatigue strength of the steel decreases. Therefore, the cylindrical roller bearing parts after quenching and tempering the larger surface residual compressive stress, but also improve the life of one of the measures.

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