Application Of Dealloying Method In Magnetic Grinding And Finishing Of TC4 Titanium Alloy

Titanium alloy with its good specific strength,high temperature resistance,corrosion resistance and other excellent properties,widely used in national defense industry,medical equipment and other important fields.With the complex structure of titanium alloy parts,the surface shape and cavity structure are more and more complex,in the processing of titanium alloy workpiece,the traditional machining methods can not meet the processing requirements.Due to the special formability and flexibility of magnetic particle,magnetic particle lapping breaks through the limitations of workpiece surface shape and cavity structure,and is applied more and more widely in complex surface machining.However,in the processing of high hardness materials such as titanium alloy,the magnetic particle grinding pressure is small,the material removal amount is small,the processing efficiency is relatively low,and the material removal thickness can not be accurately determined.How to improve the processing efficiency while realizing the quantitative removal of trace amounts is also a problem that people have been exploring.In order to improve the machining efficiency of titanium alloy and realize the quantitative removal of titanium alloy surface materials,TC4 titanium alloy material was taken as the research object.The dealloying phenomenon of TC4 in NaOH solution with different concentration was analyzed by electrochemical dealloying method,and the optimal electrolyte concentration was 1.5 mol/L.The critical voltage of dealloying was determined to be 2.1V by potentiostatic and potentiostatic polarization.The continuous and uniform nanoporous structure was obtained on the surface of TC4 titanium alloy after the dealloying test at 2.1 V in 1.5 mol/L NaOH solution.After dealloying for 3 h,6 h and 9 h,the Vickers hardness of nanoporous layer on workpiece surface decreased by 29.4%,39.5% and 46.7%,respectively.In the friction and wear test,the time of grinding ball penetrating the nanoporous layer was 11 min,21 min and 35 min,respectively,and the thickness of the nanoporous layer reached 2.2 μm,3.8 μm and 6.2 μm,respectively.Magnetic particle grinding was performed on TC4 titanium alloy and the dealloying workpiece.After 165 min of grinding,the wear marks of 6.2 μm thickness on the surface of TC4 titanium alloy were effectively removed.After 45 min grinding,the 6.2μm nanoporous layer on the surface of the dealloyed workpiece was effectively removed,and the grinding efficiency was improved by 72.7%.The quantitative removal of TC4 titanium alloy surface material was realized by using the composite processing method of dealloying and magnetic particle grinding,and the processing efficiency of magnetic particle grinding was improved by reducing the Vickers hardness of surface material.