The special steel alloy used in the construction of XD-15 bearings makes them the best ceramic hybrids in the world.
XD-15 High Nitrogen Steel Alloy is 3.5 times more corrosion resistant than 440C Stainless Steel. In the past, ceramic hybrid bearing manufacturers were faced with a choice in bearing race material: 1) The longer fatigue life of SAE52100 bearing steel when paired with the extremely hard ceramic balls, or 2) The corrosion resistance of 440C stainless steel for use in harsh environments. If they opted for the longer fatigue life of 52100 bearing steel, the intrusion of water would always be a threat to the races. If they opted for 440C Stainless, corrosion would become less of a threat at the expense of longevity. The XD-15 steel not only combines the benefits of both, but EXCEEDS them on both counts. Yes, much greater corrosion resistance than 440C and longer fatigue life than 52100 bearing steel.
XD-15 High Nitrogen Steel Alloy has a 40 percent higher load rating than SAE52100 bearing