Effect of machining-induced surface topography on corrosion behaviors of 304 austenitic stainless steel in pre-stress grinding

Aiming to explore the corrosion mechanisms on the ground surface in pre-stress grinding and pursue grinding parameters that could help obtain the machined surface with higher corrosion resistance, in the present study, a series of experiments and simulations are conducted. Firstly, the ground surfaces operated by pre-stress grinding are corroded in boiling magnesium chloride. Then, the characteristics of the surface are measured. After that, the corrosion field models which could evaluate the evolution of corrosion behaviors are established, including (1) the ground surface model considering deformation, (2) the grinding wheel model obeying non-Gaussian, (3) the model of the corrosion. The results suggest that the grinding surface's corrosion resistance strongly correlates with the machined surface topography. Proper pre-stress in grinding could improve the surface roughness of stainless steel, reduce surface defects and enhance surface corrosion resistance. Besides pre-stress, the combination of the higher linear velocity of the grinding wheel, smaller grinding depth, and lower feed speed is recommended to obtain the surface with small roughness. The corrosion form depends on the competitive relationship between topography and surface residual stress. When the surface topography is dominant, the corrosion form is the corrosion pit. Conversely, the form is corrosion crack. It is found that a high level of residual tensile stress may not be necessary at the early stage of corrosion crack initiation. However, the residual tensile stress does play a vital role in the propagation of crack. The models also indicate that the corrosion behavior on the ground surface has a polishing effect.

Automated summary

In this study, the corrosion mechanisms on the ground surface in pre-stress grinding were explored, and grinding parameters that could help obtain a machined surface with higher corrosion resistance were pursued. It was found that proper pre-stress in grinding could improve the surface roughness of stainless steel, reduce surface defects, and enhance surface corrosion resistance.