Uniformity mechanism investigation of hardness penetration depth during grind-hardening process

Grind-hardening is a new technology for steel part surface enhancing which uses thermal and mechanical composite effects on the parts in the grinding process. During the process, the workpiece surface generates hardened layer that improves the surface quality. Hardened layer may enhance fatigue strength, friction and wear properties, and corrosion resistance of parts significantly. Since component properties are influenced greatly by hardness penetration depth and its uniformity of parts, prediction of hardness penetration depth is significant to the practical engineering. First, the part is divided into cutting-in zone, middle zone, and cutting-out zone along length direction according to the characters of heat source strength changes. The mathematical models for segmented triangle heat source are carried out. Moreover, ANSYS is applied to simulate and analyze the distribution of temperature field and the change of instantaneous temperature in each zone of the grinding process. And the hardening penetration depth in each zone is predicted accordingly. Study of mechanism of depth uniformity is conducted emphatically in this paper. Results show that the change of heat intensity makes both ends of part not hardened during the grinding process. Hardening penetration depth increases gradually in the cutting-in zone and decreases gradually in the cutting-out zone. Meanwhile, the middle zone acquires deep and uniform hardened layer. Finally, comparison between predicted value and experimental value is carried on to verify the validity of source optimization model and reasonableness of prediction methods.