Effect of grinding on the fatigue strength of highly hardened steel. 1st Report, Some features of surfaces, ground with CBN or WA abrasive grains.

Abstract

A highly hardened steel (SK 5) was ground with CBN or WA abrasive grains, and some features of ground surfaces (structure, hardness, residual stress, etc.) were studied. It was found that spark-out raised compressive residual stress near the ground surfaces in every case, especially when CBN abrasive grains were used. This suggests the effectiveness of spark-out in raising fatigue strength. It was also found that grinding with CBN abrasive grains raised the hardness, in contrast to the lowering of the hardness after the grinding with WA abrasive grains. This suggests a rise in the wear resistance due to the grinding with CBN abrasive grains, contrary to the case of grinding with WA abrasive grains. The above-mentioned difference caused by the difference of the abrasive grains may be attributed to the difference in the heat conductivity, etc., of the abrasive grains, which caused the difference in the structure of the ground surfaces.