Effect Of Melt Complex Treatment On Microstructure And Mechanical Properties Of ZL301&3003 Alloys

Aluminum and its alloys can provide comprehensive excellent properties such as corrosion resistance,light weight and high strength.At present,according to the different processing methods of aluminum alloy,it is mainly divided into cast aluminum alloy and deformed aluminum alloy.For cast aluminum alloys,lightweight and high-strength aluminum-magnesium alloys have gradually become hot spots,such as the body of a car,which can reduce the vehicle weight while increasing the strength of the vehicle body.For deformed aluminum alloys,its outstanding feature is to guarantee the satisfaction of structural materials.The strength at the same time has excellent processability and is widely used in packaging and storage materials.Although the application of the two types of aluminum alloys has been very extensive,the related researches have their own deficiencies,and even some of the theories are in conflict with each other.The current theoretical guidance can no longer meet the increasingly high production demands.Therefore,in this paper,the aluminum-magnesium alloy ZL301?Al-10Mg?deformed aluminum-manganese alloy 3003?Al-1.2Mn?was studied as the object of study,through the refinement of strengthening technology to explore ways to improve the performance of the two alloys,to achieve the current industrial production of alloys Increasingly demanding performance standards.The specific research content is as follows:?1?By DSC analysis,it was found that the melt structure of ZL301 alloy changed at 800,and the heat treatment temperature of ZL301 alloy was determined to be 800;and DSC analysis of 3003 alloy also found that the melt structure of 3003 alloy changed at 920.Similarly,it was determined that the thermal processing temperature of the 3003 alloy is 920.The microstructure and mechanical properties of ZL301 and 3003 alloys were optimized after thermal treatment.?2?There is a typical peritectic reaction in Al-Nb,which has the potential to become a grain refiner.Experiments show that Al₃Nb induces?-Al grain nucleation by peritectic reaction as the temperature decreases to peritectic reaction temperature.Therefore,refinement of grains,Al₃Nb formed by Nb and Al is more stable than Al₃Ti,and Ti poisoning effect can be effectively avoided.The final grain size of the aluminum alloy added with Nb as a refiner does not depend on the cooling rate,so the Nb refiner can be applied to a wider range of casting processes than the Ti refiner,and Nb can work on the ZL301 alloy and the 3003 alloy.For strengthening,for the ZL301 alloy,when the addition amount of Nb is 0.05 wt.%,the tensile strength,yield strength,elongation,and hardness reach the maximum values of 172MPa,121 MPa,77 HB,and 4.1%,respectively.The grain size decreases from 480?m to 190?m.For 3003 alloy,the grain size and mechanical properties are best improved after addition of 0.1 wt.%Nb.The grain size decreases from 180?m by 100?m,and the tensile strength,yield strength,hardness and elongation reach 167 MPa and 113 MPa,50 HB,22.4%,respectively.?3?Experimental verification shows that the new Al-Nb-B refiner can effectively refine the ZL301 alloy and 3003 alloy,and its sensitivity to cooling rate is lower than that of Al-Ti-B.Newly developed Al-2Nb-2B The XRD,SEM and EDS analysis of the master alloy show that the phases contained in the master alloy are NbB₂,AlB₂ and Al₃Nb.The Al₃Nb phase can be used as a peritectic reaction.The peritectic reaction becomes the effective nucleation core of?-Al,which improves the nucleation efficiency of Al;the reaction product of Al-B eutectic reaction and the heterogeneity of NbB₂ as?-Al core,so that the grain refinement.For the ZL301 alloy,the appropriate grain refiner is 3 wt.%,the grain size of the alloy can be refined to 50?m,and the tensile strength,yield strength,hardness and elongation are respectively 208MPa,163 MPa,and 82 HB.12.8%,Zl301 alloy increased by 47.5%,101.2%,30.2%,and433.3%respectively when Al-Nb-B refiner was not added.For 3003 alloy,when the added refiner was 3 wt.%,The grain size was reduced from 180?m to 40?m without the addition of the refining agent,and the tensile strength,yield strength,hardness,and elongation were 182MPa,139 MPa,58 HB,and 34.1%,respectively,with and without addition of Al-Nb-B.When with B refining agents,they increased by 50.4%,75.9%,81.3%,and 90.5%,respectively.?4?The composite treatment has an ideal effect on both alloys,and has a better effect than the effect of adding a refiner alone or a single heat treatment.The alloy melt passes through the new Al-Nb-B After refinement of the chemical agent,the cold material added during the rapid cooling process can also be refined by the intermediate alloy.After the alloy melt is subjected to thermal speed treatment,the refiner refines the high-temperature melt in the alloy melt.The small-size atomic clusters are too late to grow when they cool down rapidly,and they are retained in the melt at lower temperatures to develop into a large number of crystal embryos,thereby promoting the formation of crystal nuclei and grain refinement.The ZL301 alloy after composite treatment has a tensile strength,yield strength,hardness and elongation of 268 MPa,211 MPa,97 HB and 12.2%,respectively,which is 90.1%,160.5%,54.0 higher than that of the alloy without any treatment.%,408.3%;3003 alloy after combined treatment has tensile strength,yield strength,hardness and elongation of 205 MPa,142 MPa,63 HB,35.0%,which is 69.4%higher than that of 3003 alloy without any treatment.79.7%,96.9%,95.5%.