Surface microstructure:

1, the impact of mechanical polishing. The mechanical polishing of austenitic nickel-chromium stainless steel, such as 1Cr18ni95Ti, only uses abrasive to level the surface under a large directional pressure. Therefore, the surface has a certain plastic deformation structure characteristic — fibrous structure, i.e., Belpet layer.

2, the influence of electrochemical polishing. Ma Shengli et al. studied the surface microstructure of 1Cr18ni95Ti stainless steel after electrochemical polishing in phosphoric acid/sulfuric acid system electrolyte from typical fibrous structure to uniform and dense granular grain structure morphology. This is obviously related to the polishing process mechanism.

Usually when the current through the electrolyte, stainless steel in the anode, the metal surface of the micro convex preferential dissolution phenomenon, and the grain of different crystal surface micro dissolution rate is not the same, resulting in the emergence of grain edge. However, the microstructure of the surface varies greatly under different electrochemical polishing conditions. For example, in the electrolyte of 65%(wt) water, when the anode current density is 30A/dm2 and t is 70℃ for 15min, better surface polishing effect can be obtained. When the anode current density (DA) is too low (DA< 20A/dm2= or too large (DA< 40A/dm2), or too high temperature (> 90℃) or too low (< 50℃=), or too long polishing time (> 25min) or too short (< 10min), are not conducive to the improvement of surface polishing quality.