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Firstly, simulation is used to analyze the temperature curve in pre-stress hardening grinding (PSHG). Then, according to the start and the end time of martensitic transformation, three time nodes are selected to study the pre-stress time characteristic; they are 1 s, 3 s, and 7 s after grinding. The influence of pre-stress on the initial temperature and content of martensite transformation in cooling is analyzed; the results indicate the content of martensite increases over the pre-stressed unloading time. To test the theory, experiments of PSHG with different unloading times are carried out. The microstructure of the grinding hardening surface is observed and explored by scanning electron microscopy (SEM). Then, the SEM images are binarized to get the martensite content on the hardening surface. The experimental results show martensite content is consistent with the theoretical analysis. Lath martensite and flake martensite can also be found in these pictures. Flake martensite slightly increases while unloading at 7 s, as it forms at a lower temperature. So the pre-stress time characteristic influences both the martensite content and the morphology of martensite formed.

Pre-stress hardening grinding (PSHG) is a complex process that combines pre-stress grinding and grinding hardening. Pre-stress, as input stress, has been working throughout the grinding process. Since the grinding heat generates on the surface of material, unloading the pre-stress at different time nodes will affect the phase change after the grinding process. In this paper, the effect between pre-stress unloading time and the grinding hardening is further studied. In order to study the effect of pre-stress unloading time, experiment and simulation are used for analysis and to optimize grinding hardening layer in the PSHG process. After the PSHG experiment, the microstructure of the grinding-hardened surface is observed and investigated by scanning electron microscopy (SEM). And the SEM images are binarized to obtain the martensite content on the hardened surface. It is showed that as the pre-stressed unloading time increases, the martensite content increases. Then, a simulation model is established based on the heat conduction equation, initial boundary conditions, and latent heat of phase change. According to the simulation results, three time nodes are selected to study the unloading pre-stress. The pre-stress unloading time affects the mechanical thermal stress of the material surface layer, but has little effect on the inner layer. In the simulation, the influence of the pre-stress unloading time on the mechanical-thermal stress of the surface is compared. Finally, the effects of pre-stress unloading time on the phase transition and phase transition stress are discussed.

Surface grinding is always accompanied with chatter due to self-excited vibration. It often leads to an unexpected impact on the quality of the workpiece’s topography. However, the chatter is regarded as a harmonic vibration in most topography researches. This may lose preciseness when the relative vibration and the abrasive trajectory are taken into consideration. In order to study the relationship between the system’s dynamic characteristic and the workpiece’s topography, a two-DOF (degree of freedom) dynamic model with time-delay characteristic is established accordingly. Then, reliability analysis is introduced into chatter vibration by analyzing the fluctuations of dynamic parameters with two analysis methods, namely Monte Carlo (MC) and first-order second-moment (FOSM). With the above two reliability analysis methods, the calculations are carried out as follows: firstly, the non-Gaussian distribution of the grinding wheel based on Johnson Curves and filter techniques is established. Secondly, the results of the dynamic analysis are coupled into the grain trajectory equation. Thirdly, the influence of the wheel grinding parameters and dynamic parameters on the surface height is discussed by coupling the dynamic characteristics into the simulation model. Finally, the simulations and experiments are carried out on the impact of different feeding rates and sections on the workpiece to the surface heights. The comparisons verify the prediction of the simulation model. The obtained conclusions could be applied to optimize the workpiece’s topography by regulating the grinding parameters and dynamic parameters to weaken the chatter’s influence.