Effect Of Cold Rolling And Aging Treatment On Friction And Wear Properties Of Al-Zn-Mg-Cu Alloy

Al-Zn-Mg-Cu alloys have been widely used in aerospace,weapon manufacturing and other fields due to their low density,high strength and good corrosion resistance.However,high friction coefficient and poor wear resistance,which limit their further application and development in some fields.At present,most of the research is still on improving the properties of the alloy by optimizing the heat treatment process,However,this strengthening method is limited due to the limitation of the solid solubility of alloying elements in the aluminum matrix.Therefore,a treatment method combining deformation and aging has gradually attracted the attention of researchers.In the present work,Al-Zn-Mg-Cu alloy was processed by cold rolling(low,medium and high deformation: 20%,40% and 60%)and aging.The effects of cold rolling and aging on the microstructure and mechanical properties of the alloy were studied by means of metallographic optical microscope(OM),scanning electron microscope(SEM),X-ray diffractometer and Vickers hardness tester.The effects of cold rolling and aging on the wear mechanism and friction and wear characteristics of the alloy were studied by means of SEM and EDS.The results are as follows:(1)After cold rolling,the grain structure is refined and deformed,and the insoluble phase is broken and elongated.After aging treatment,there is no obvious change in the morphology of grain structure.(2)After cold rolling,the intragranular dislocations multiply,the strength and hardness increase,and the plasticity decreases.After aging treatment,the plasticity is improved.The samples with medium and low deformation amount maintain a certain work hardening and have a good aging strengthening effect,and the strength is improved.The poor aging strengthening effect of the samples with high deformation is not enough to make up for the decline of work hardening,and the strength is slightly reduced.(3)Hardness,plasticity and work hardening together determine the wear resistance of materials.Increasing the amount of deformation can increase the hardness before and after wear of the alloy,thereby improving the wear resistance of the material.After aging treatment,the samples with medium and low deformations have strong work hardening ability while maintaining high hardness,which greatly improves the wear resistance.The decrease in matrix hardness and the lack of work hardening ability of high deformation specimens resulted in a slight decrease in wear resistance.(4)After cold rolling,the wear mechanism of the samples is the coexistence of abrasive wear,adhesive wear and oxidative wear.After aging treatment,the wear mechanism of the samples with medium and low deformation changed from the coexistence of various wear mechanisms before aging to the dominated by abrasive wear,the wear mechanism of the samples with high deformation is still the coexistence of abrasive wear,adhesive wear and oxidative wear.