Effect of low-temperature liquid oxy-nitriding on wear behavior of austenitic stainless steel
[Introduction]Austenitic stainless steels are widely used in the manufacturing of various avionic components,but their hardness and wear resistance are not good.[Method]The surface modification of 304 austenitic stainless steel was carried out by low-temperature liquid oxy-nitriding(LTON).The microstructure and microhardness distribution along the cross-section of the LTON layer were characterized by using scanning electron microscope,transmission electron microscope,and Vickers hardness tester.The wear resistance of the modified layer was studied by friction and wear test.[Result]The low-temperature liquid oxy-nitriding layer was composed of the outer compact Fe3O4 phase and the inner nitrogen-rich S-phase.The S-phase is a kind of supersaturated solid solution containing nitrogen and plenty of dislocations,stacking faults,and twin crystals,so it has high hardness.The temperature and load during the friction and wear test affected the wear behavior of 304 austenitic stainless steel.Both the increase in temperature and load led to a slight decrease in the average friction coefficient of 304 austenitic stainless steel and an increase in its wear volume loss,no matter whether it was treated by LTON or not.After being treated by LTON,the duration of the initial wear stage of 304 austenitic stainless steel was shortened,and its maximum wear volume loss was decreased from 1.086 mm3 to 0.144 mm3 under a load of 10 N at 200℃.[Conclusion]The wear resistance of 304 austenitic stainless steel can be significantly improved by LTON.
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