Effect of Process Variables on the Hardness Achieved at the Surface and Improvement in Rolling Contact Fatigue Life of 0.2 Percent Carbon Steel Due to Tufftride Surface Treatment

In this paper the effects of time of treatment and quenching media on the surface hardness achieved by tufftride treatment on certain selected steels as well as improvement in rolling contact fatigue life of 0.2 percent carbon steel due to tufftride treatment have been discussed. The increase in hardness at the surface due to tufftride treatment depends essentially on the initial hardness. Water quenching is the best and it gives about 20% to 25% higher surface hardness than oil quenching. The hardness achieved depends also on the time of treatment. However beyond 120 minutes of treatment for the steel tested, the increase in hardness is not very significant.

The improvement in rolling contact fatigue life of 0.2 per cent carbon steel due to tufftride treatment is discussed here in relation to surface finish, virginity of the specimen and lubricant viscosity. Tufftride treated surfaces have pitting limit which is about 2.7 times the untreated pitting limit. Improvement in surface finish improves the pitting life. Changes in bulk viscosity of the oils and prior working of the specimen have no significant influence on pitting life. The microhardness distribution studies reveal lack of strain hardening of the tufftride surfaces due to working.