Experimental studies of rolling and rolling-sliding contact fatigue behaviour of high nitrogen alloyed Cronidur-30 bearing steel

Abstract

This study analyzes the rolling and rolling-sliding contact fatigue behavior of Cronidur-30, an advanced nitrogen-alloyed steel tempered at high and low temperatures, with a comparative analysis against AISI 440C. The experiments were separately conducted under pure rolling (0 % slip) and rolling-sliding (0.5 % slip) conditions, using base and graphene-enhanced lubricants (GNL). Recent works among these materials revealed that the Cronidur- 30 material exhibited a longer rolling contact fatigue (RCF) life (L₁₀ life) compared to 440C. Given the difficulties in predicting RCF L₁₀ life under slip conditions, anti-wear performance under rolling contact fatigue conditions was evaluated by quantifying material removal during tests at zero and 0.5 % slip conditions. Compared to 440C, Cronidur-30 showed reduced anti-wear performance in both pure rolling and slip conditions with base lubrication. Although the use of GNL followed the same trend in anti-wear performance across these materials, it still showed a notable improvement over the base lubricant. In pure rolling conditions, GNL led to improved wear performance relative to the base lubricant, with 440C exhibiting the greatest improvement of 53 %, and Cronidur-30 showing a 32 % increase compared. Under slip conditions with GNL, Cronidur-30 achieved a 98 % improvement in anti-wear performance, significantly higher than the 38 % improvement observed in 440C compared to the base lubricant. This enhancement is primarily attributed to the graphene nano-additives, which reduce metal-to-metal contact and thus improve antiwear performance. The results highlight the potential of graphene nano lubricants to significantly enhance the wear resistance of aerospace steels under slip-rolling conditions.