![]() ![]() But with that said, we have also had success with some suppliers with through-hardened parts when compared to a baseline case-carburized material. Flavor Text: A little color never hurt anyone. Our testing has proven that we get a very wide variation on through-hardened part life and we believe that it is very much attributed to steel melting practices. Description: It has been color case-hardened through the application of wood charcoal at high temperatures. Without performing actual life testing or without valid endurance test results from suppliers comparing the two materials, the current life factor data provides the most accurate information regarding estimating bearing life. The life adjustment factors are based on information available within the text, “STLE Life Factors for Roller Bearings” (E.V.Zaretsky). Based on this information we would estimate a reduction in fatigue life on the through-hardened product of 0 to a maximum of ½ of that of the case-carburized product. However, based on currently published data, on similar case-carburized steels and vacuum arc re-melting practices used for commercial steel we have a life adjustment factor range of 4.5 – 6.0. In the case-carburized bearing it is more difficult to identify the life factor. Generally speaking, it is believed that a 52100 through-hardened bearing life factor would be between 3 – 4.5, based on using either an air melt or vacuum processed melting practices on 52100 steel. ![]() It is only through advanced melting processes of the raw material that bearing life adjustment factors for materials increase significantly. It is important to note that tests conducted to develop life factors for bearings based on steel material find 52100 steel to be higher or better than most case-carburized steels. Generally speaking, case-hardened steels tolerate substantial damage progression without catastrophic failure during the interval between the onset of a problem and when routine maintenance identifies the need for repair. Sub-surface cracks (spalls) or surface initiated defects that lead to cracks, have a propensity to materialize into a catastrophic failure with through-hardened steel. Fracture toughness is the property that defines the stress to initiate rapid fracture in the presence of a local defect such as a spall or other surface deterioration. A review of application criticality and imposed bearing stresses can dictate the usability of through-hardened ring material in tapered roller bearings.Ĭase-hardened steels exhibit higher fracture toughness than through-hardened steel (52100). Case-hardened bearing components are typically used in bearing applications involving high loading conditions. In such applications, case hardening can provide a part that does not fracture, but also provides adequate wear resistance on the surface.Although most bearings, in general, are made of through-hardened 52100, tapered roller bearings in the US market have typically been manufactured with case-hardened steels. Case hardening steels are particularly suitable for:īecause hardened metal is usually more brittle than softer metal, it is not always a suitable choice for applications where the metal part is subject to certain kinds of stress. Components that are subjected to severe impacts and high pressures are generally case hardened. One advantage of this method of hardening steel is that the inner core is left untouched, and therefore still processes properties such as flexibility and relative softness.Ĭase hardening is usually performed after the formation of the component into its final form. The surface improvement not only increases the product strength, but also assists in avoiding weakening of the iron. ![]() The addition of the low-carbon metal creates a material that can be molded easily into desired shapes. The combination of metals produces a product that is much harder. Case hardening is a simple method of hardening steel involving the use of metal that has low carbon content, and combining it with a metal that has a higher carbon content. ![]()
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