On The Structures And Properties Of Deformed Al-Si-Cu-Mg Aluminum Alloy

In the mechanical industry,the use of aluminum alloys instead of steel materials,reducing the weight of mechanical parts is an important means to achieve energy conservation and emission reduction.At present,most aluminum alloys used in wear-resistant parts have the phenomenon that the mechanical properties can meet the requirements but the wear resistance is not good.For improving the wear resistance of aluminum alloys while maintaining sufficient mechanical properties,a new type of Al-8.3Si-3.3Cu-0.9Mg alloy was fused in this paper.The influences of extrusion and heat treatment on the mechanical properties and microstructure s of aluminum alloy are studied,and the friction and wear properties of extruded and heat treated alloys are analyzed.The hot extrusion experiments showed that the original coarse dendrites in the Al-8.3Si-3.3Cu-0.9Mg alloy are extruded and broken,and the segregation is improved to a certain extent.A large number of equiaxed grains appear and the plate-like eutectic Si disappear,broken into elliptical or granular.The second phase particles are fine and evenly distributed.The macroscopic microstructure of the alloy is fibrous.The tensile strength of the alloy increases from 254 MPa to 261 MPa,and the elongation reached 11.45%,which increased 317.9%.The optimum heat treatment process of the alloy by orthogonal test is as follows: solution treatment 510 ?+2.5 h,aging treatment 180?+5 h.After the solid solution aging treatment,the second phase precipitated by precipitation is more dispersed and fine,the distribution is more uniform and the grain growth phenomenon.The mechanical properties of the alloy have been greatly improved.The tensile strength is 465 MPa,compared with the as-cast alloy,the increase is 83.7%.The specific hot extrusion state is 78.2%.the elongation is 11.05%.At the same state,the wear resistance of the heat treated alloy is higher than that of the hot extruded alloy,and the friction coefficient of the two different states alloy has less volatility with time,which indicates that the Al-8.3Si-3.3Cu-0.9Mg alloy has stable and continuous wear resistance.Load and sliding speed have an important effect on the friction and wear properties of Al-8.3Si-3.3Cu-0.9Mg alloys.With the increase of load,the wear rate of the alloy increases gradually,and the friction coefficient decreases first and then increases.When the load is 5N,the alloy is mainly fatigue wear,accompanied by abrasive wear and oxidation wear.When the load is 10 N and 20 N,the wear mechanism of the alloy is mainly fatigue wear and oxidation wear,but also adhesive wear occurs.For sliding speed,the wear rate of the alloy increases with the increase of sliding speed,and the friction coeff icient has the opposite trend.With the increase of sliding speed,the heat produced by friction by-product increases gradually during friction and wear,which accelerates the formation of wear surface oxides.When the sliding speed is low,the alloy mainly occurs oxidation wear,and a small amount of fatigue wear and abrasive wear occurs;When the sliding speed is high,the wear mechanism is mainly oxidation wear,fatigue wear and adhesive wear.