Complicated microstructure transformation mechanism of the greenly grinding coating layer

Abstract

The grinding surface mechanical property is important for its working life span, which is determined by the microstructure distribution. To improve the machining mechanical performance, the greenly grinding generated heat is utilized to generate the coating layer without extra liquid. However, the coating layer microstructure composite is difficult to predict due to the non-steady grinding temperature. A digital complicated microstructure transformation (DCM) model is established and coupled with the transient grinding heat based on the validated improved finite difference method. The austenization, the ferrite reverted transformation, the cementite precipitation, the bainite transformation and the martensite transformation are all considered and automatically distinguished according to the grinding coating CCT. The analytic results indicate that the larger grinding depth mainly increases the bainite content, which can be restricted by improving the feeding rate, and the quicker feeding rate can increase the martensite content by three times. Combined with the measurement of corresponding representative mechanical performances (hardness and the residual stress), the achieved model is verified as an effective tool to realize the microstructure prediction. The research brings about a novelty macro mechanical property control of the grinding coating layer and is significant for achieving higher mechanical performance in surface strengthening manufacturing components.

Keywords

• Greenly grinding coating
• Non-steady temperature field
• Complicated microstructure transformation
• Mechanical performance