Surface Integrity Of Stainless Steel By Mechanical Grinding And Corrosion Resistance

AISI 316 austenitic stainless steel is mechanical grinded by 304SS wire brush or high Mn steel wire brush at spindle speed of 550?2000 rpm,or mechanical grinded by two kinds of wire bursh combined with 320#abrasive cloth flap wheel at the spindle speed of 2000 rpm.To investigate surface geometry,surface roughness,phase,residual stress and anodic polarization curve,electrochemical impedance spectroscopy,Mott-Schottky curve in NaCl solution of the sample mechanical grinded by single grinding and combination grinding,determining surface integrity parameters of AISI 316 austenitic stainless steel sample mechanical grinded by single grinding and combination grinding on the influence of corrosion resistance.The results indicate that mechanical grinding by 304SS wire brush or high Mn steel wire brush combined with 320#abrasive cloth flap wheel respectively achieve to finish stainless steel surface efficiently.Combination grinding surface roughness is between 0.5?0.8 mm,remains austenitic phase and removes Cr2O3 and wire brush wear debris generated during mechanical grinding by single grinding.Surface roughness of sample mechanical grinded by filament diameter of 0.3 mm high Mn steel wire brush is between 0.287?0.967 mm,the thickness of surface overlaps generated during mechanical grinding is 1 mm.Surface roughness of sample mechanical grinded by filament diameter of 0.3 mm and 0.2 mm304SS wire brush is between 2.410?3.975 mm and 1.230?2.309 mm,respectively,the thicknesses of surface overlaps are 7 mm and 5 mm,respectively.The anodic polarization curve of sample mechanical grinded by single grinding and combination grinding in 3.5%NaCI solution indicates that all samples grinded by single grinding exhibit poor performance of corrosion resistance.The corrosion potential Ecorr of Sample grinded by combination grinding is-140 mV,passivation current density Iss is 0.4 A/cm2,breakdown potential Ep is 250 mV,compares to sample grinded by 1000#water sand paper only reducing in breakdown potential of 50 mV and exhibits similar corrosion resistance,compares to sample mechanical grinded by single grinding exhibiting remarkable performance of corrosion resistance.When surface roughness is between 1.410?2.831 mm,metastable pitting potential(Em)of stainless steel in O.Olmol/L NaCl solution decreases with the increase of surface roughness,meanwhile the occurrence of metastable pits directly affects the stable pitting potential(Ep),the stable pitting potential(Ep)decreases with the decrease of metastable pitting potential(Em).Electrochemical impedance spectroscopy of sample mechanical grinded by single grinding and combination grinding in 0.01mol/L NaCl solution indicates that the diameter and Modulus |Z| of the capacitance of combination grinded sample increase,and the phase angle platform gets higher,the passive film resistance Rp increases from 7.533×104 ? to 2.764?105 ? and Y0 which characterises the capacitance of the passive film decreases from 7.836x10-5 F·cm-2 to 5.331×10-5 F·cm-2,it changes the structure of electrical double layer,enhance the corrosion resistance.Mott-Schottky curve indicates that the donor density of the passive film of combination grinded sample decreases from 5.55×1021 to 4.14×1021 cm-3,the acceptor density decreases from 9.13×1021 to 5.10×1021 cm-3,The flat band potential Etb decreases from-601 mV to-697 mV,density of defects decreases,corrosion resistance enhances.