Research On The Influence Of Grain Refinement And Rolling On The Microstructure And Properties Of 1070Al For Wire

Aluminum and aluminum alloys are commonly used in the production of wires and cables because of their advantages,such as low cost,low density,good electrical conductivity and strong forming ability.On the premise of guaranteeing the good electrical conductivity,sufficient strength and hardness,the aluminum and aluminum alloys can be used in electrical engineering.Besides,aluminum alloy wire or cable conductors must be properly deformed during the production process.Therefore,aluminum and aluminum alloys must have good plasticity.However,good electrical conductivity and strength are usually in conflict.In this paper,grain refinement and annealing treatments are used to improve the properties of pure aluminum.The microstructure and the electrical conductivity are investigated.The precipitation movement of the refined particles in pure aluminum is explored too.The main results of the study can be outlined as follows.(1)The grain refinement process increases the grain boundary area.So the excellent grain refinement effectiveness and good electrical conductivity is difficult to be simultaneously obtained due to the influence of both the grain boundary and excessive Ti.So the Al-Ti-B master alloy without or with less excessive Ti elements have been tried to prepare.There are an effective way to improve the electrical conductivity of aluminum wires.It is found that the grain refinement effectiveness of the Al-Ti-B master alloys prepared from the Al-5Ti-1B and Al-3B master alloys at720°C is much better than those prepared using the Al-10Ti and Al-3B master alloys.Because the high refinement potency Ti B₂ with Ti Al₃ 2DC in the Al-5Ti-B can be kept in the new master alloys.And the new Al-Ti-B master alloy does not contain excessive Ti elements.As a result,using the prepared Al-Ti-B master alloys as the refiners,both the good grain refinement effectiveness and improved electrical conductivity of Al can be realized.(2)When the master alloy is used to refine aluminium wires,the long-term holding test is easy to cause the decline of the refining effect mainly due to the settling of fine particles.Therefore,the research on the settling movement of fine particles is helpful to investigate the generation of refining depression.In this research,Al-5Ti-1B,Al-3B and Al-8B master alloys,as raw materials,were added into aluminum melt for holding test.It is found that the settling processes of Ti B₂ particles and Ti Al₃ particles are similar during the Al-5Ti-1B holding test,and the sedimentation rate is much greater than the theoretical value.However,when Al-5Ti-1B master alloy is added to the aluminum melt,the precipitation rate of Ti B₂ particles in the center of the aluminum melt is higher than that in the surrounding area,and more fine particles are gathered in the center of the bottom layer and the wall boundary area.In addition,the number of precipitated particles in the aluminum melt with the addition of Al-3B is more than that with the addition of Al-8B,but for the distribution density of precipitated particles,the former is less than the latter.(3)The microstructure and texture changed significantly during the rolling and heat treatment of aluminum wires,which affected their properties.Therefore,it is important to explore the relationship of them.The cold rolling and subsequent annealing with various holding times were conducted on 1070Al.The experimental results indicated that the annealed 1070Al have elongated grain and fiber structures along RD direction.Both the recovery and recrystallization occurred during annealing treatment.With prolonging the annealing time,the average grain size continuously increases.And the fraction of texture components varies significantly.The texture intensity increases during the recovery process,and decreases with the proceeding of recrystallization.The electrical conductivity of the 1070Al gradually increases with the increase of annealing time.However,the annealing treatment results in the decrease of tensile strength and the increase in elongation of the 1070Al.