The effect of grinding parameters and gas nitriding depth on the grindability and surface integrity of AISI D2 tool steel

The present contribution aims to study the combination effects of pre- and post-nitriding grinding and gas nitriding parameters (depth of cut, abrasive type, cooling mode, and nitriding depth) on the material grindability and generated surface integrity of AISI D2 tool steel. As a result, it is shown that grinding with sol-gel abrasive type increases AISI D2 surface hardness before gas nitriding when compared to Al₂O₃. To remove the brittle white layer, a fine post-nitriding during grinding experiments shows an improved grindability, yet an increase of total and arithmetic roughness with all grinding combination’s parameters. After AISI D2 gas nitriding at 24 and 36 h, using the sol-gel abrasive type and conventional cooling mode, a compressive residual state of stresses was induced for lower depth of cut in grinding. When drawing the evolution of grinding specific energy regarding process parameters, it was possible to distinguish between burned and non-burned surfaces. This has helped to perform comparison of the AISI D2 steel ground surface burning under various grinding conditions after and before nitriding. Moreover, it was observed that thermal cracks appear only on severe grinding with combination of Al₂O₃ abrasive type and conventional cooling mode.