Rolling Deformation Strengthening Of Complex Brass And Its Effect On Surface Properties

China is a major consumer of copper.The annual production of copper accounts for about 50%of the world's total production.However,the amount of copper found in China accounts for only 4.6%of the world's total reserves.Therefore,it is more important to increase the overall performance and efficiency of copper alloys in order to alleviate the shortage of copper resources.his technology does not change the chemical composition of the material surface,and directly performs cold processing on the material substrate.The structure of the surface of the material changes in the way of a continuous gradient,and the bonding force is firm and is not easy to fall off.In addition,the equipment used for deformation strengthening of the surface of the material is simple and inexpensive,the process is easy to operate,and the effect is remarkable.The use of this method to improve the performance of copper alloys is of great economic importance.In this dissertation,the most widely applied complex brass alloys in copper alloys are used as experimental materials.The surface deformation of the complex brass alloys is strengthened by rolling.Electronic scanning,microscope,metallographic microscope,X-ray diffractometer,white light interferometer,hardness machine,UMT-2 multi-functional friction wear machine,and electrochemical workstation are used to analyze the microstructures and properties of the copper alloy surface and get the main conclusions:?1?When the spindle speed is 450r/min,the indentation amount is 1mm,and the feed rate is 0.14mm/r,the depth of the deformation layer is about180um.Then close to the surface of 90um,the?and?phase grains are severely shattered and form nanocrystals,and the reinforcement phase of SiMn is embedded therein and arranged parallel to the surface.Close to the surface of90-180?m,the?-phase is elongated,and the?-phase and the silicon-manganese strengthening phase are distributed along the grain boundaries.?2?Copper alloy surface rolling can reduce the surface roughness.Process parameters such as spindle speed,pushing amount,and feed rate have a significant effect on the surface roughness.When the rolling amount increases,the roughness first decreases and then increases.At a rolling amount of 1 mm,the roughness Ra is a minimum of 0.36.When the rolling amount is 2 mm,it abruptly rises to 1.6.And peeling and cracking occurs in the surface layer.The slower the feed rate,the more uniform the surface is rolled,and the lower the roughness is.The faster the feed rate is,the less the rolling is,and the higher the roughness is.Spindle rotation speed and roughness have a positive correlation.The lower the rotation speed,the lower the surface roughness.?3?There is a corresponding relationship between the microhardness of the surface layer and the microstructure of the surface layer,and it also shows a gradient distribution.The hardness value decreases with the depth of the surface layer.If the spindle speed is changed,other parameters unchanged,the depth of the hardness layer does not change,but the most surface layer hardness changes significantly.The depth of the hardness layer increases as the rolling pressure increases.?4?Deformation strengthening of the complex brass surface enhances its friction and wear properties under oil conditions.In the oil-lubricated environment,the wear rate of the rolled specimen is reduced by approximately 2times at 50 N,15%at 75 N,10%at 100 N,and approximately 40%at 125N.The rolled specimens are slightly abrasive at 50 N and 75 N.The wear is mainly layered and abrasive when the load is 100 N.The wear mechanism at125 N is the fatigue wear of abrasive wear and oxidation wear.It may be that secondary surface strengthening and oxidized abrasive particles together that reduce the wear rate of 125N.?5?The potentiodynamic scanning electrochemical corrosion is carried out in a mass fraction of 3.5%NaCl solution.The corrosion potential of the rolled sample is 240 mV higher than the original sample of 204 mV,and the corrosion current density is 2.4?10^-6 Acm^-2,which is much lower than that of the original sample 41.2?10^-6 Acm^-2.Rolling strengthens the corrosion resistance of complex brass.In the electrochemical corrosion process,the original sample shows severe dezincification corrosion,and the surface roughness of the sample decreases after rolling.And the residual compressive stress and deformation texture together improve the electrochemical corrosion performance.