Effect Of Abrasive On Surface Corrosion Resistance Of 304 Stainless Steel

Typical abrasives grinding on stainless steel surfaces does not dramatically impro ve its corrosion resistance,and hard abrasives will cause secondary scratches on the su rface of stainless steel during the grinding process,affecting its surface processing qua lity.In this thesis,Al base quasicrystal abrasives were selected for comparison with co nventional abrasives,and the optimal grinding parameters for grinding 304 stainless st eel with four different abrasives were determined by designing orthogonal experiment s to optimize the surface passivation process of stainless steel,analyze the corrosion re sistance of stainless steel using impedance spectra,polarization curves and other electr ochemical testing methods,and study the effect of different abrasives on the surface p assivation effect of 304 stainless steel.The below four items were obtained:（1）The surface grinding level of the workpiece was judged based on the mater ial surface-related parameters.With the help of orthogonal experiments,optimized par ameters were obtained for grinding 304 stainless steel with four types of abrasives:qu asicrystal,diamond,Al₂O₃ and Si O₂.To ensure the lowest surface roughness with low surface removal rate,the optimal grinding parameters were determined as follows:gri nding pressure 2 N,grinding time 9 min,grinding revolution 200 r/min,and quasicrys tal abrasive.（2）By using the one-factor experimental method,electrochemical passivation of 304 stainless steel to determine the optimal parameters,304 stainless steel passivati on potential range of 0.1～0.9 V,this thesis compares three electrochemical passivati on potential 0.1 V,0.5 V and 0.8 V in 10 min,30 min and 50 min three different passiv ation time generated passivation film quality,determine the optimal passivation param eters:passivation potential 0.5 V,passivation time of 10 min.（3）Design orthogonal experiments to determine the optimal parameters of che mical passivation of 304 stainless steel,by observing the level of impact of each eleme nt on the passivation film,determine the optimal parameters of chemical passivation:nitric acid passivation solution concentration 5 mol/L,passivation time 30 min,passiv ation temperature 25℃.（4）Quasicrystal abrasives are effective in improving the corrosion resistance of304 stainless steel.When air passivation,the passivation film impedance value of different abrasives is in an order of magnitude,and the passivation film impedance value of quasicrystal abrasives is the largest,reaching 3.75×10⁵Ωcm²;When electrochemical passivation,the passivation film impedance value of quasicrystal abrasives is an order of magnitude higher than other abrasives,reaching 3.85×10⁵Ωcm²;When passivated under chemical conditions,the impedance value of the passivation film treated with quasi-crystalline abrasives increased with the increase of soaking time and reached 4.17×10⁶Ωcm² at 120 h,this is much higher than the impedance value of 5.36×10⁵Ωcm² for the workpiece without immersion treatment.The other three conventional abrasive-treated workpieces showed a trend of increasing and then decreasing passivation film impedance values with increasing immersion time.