Grain Refining Of Wrought Alloy And Casting Alloy Prepared With ELTA By AlB Master Alloy

At present, aluminum and its alloys are mainly refined by AlTi, AlTiB master alloy in their melt, but there are many defects about these master alloys, such as complicated production technology, high cost, poor resisting fading ability and so on. Titanium addition by electrolysis is a new technology of producing aluminum containing low content titanium. The theory and practice show that this approach not only decreases the cost and reduces production technology, but also has excellent grain refining effect. It can obviously improve the grain refining effect of titanium which is added by electrolysis in melt. However, the effect of AlB master alloy on the grain refining of alloy prepared with ELTA need further study. Therefore, the grain refining effect of wrought and casting alloy prepared using ELTA was investigated in this paper. The following work is primarily studied.Firstly, the effect of AlB master alloy on the grain refining of 6009 wrought alloy prepared respectively with pure Al and ELTA was investigated. The result shows that the grain refining effect of 6009 alloy prepared using pure Al by AlB master alloy has poor effective, but it has excellent grain refining effect of 6009 alloy prepared with ELTA. When the 6009 alloy was prepared by ELTA and was under certain Ti content, the grain size declines with the increase of B/Ti mass ratio. The best grain refining effect is obtained at B/Ti mass ratio of 1:5; the grain size coarsens obviously at B/Ti mass ratio of 1:2.22 (the stoichiometric value for TiB₂). It notes that B in the melt reacts to Ti to form TiB₂ particles completely, and the TiB₂ particles alone have not good grain refining effect. But the existence of TiB₂ hampers grain grow, as a result, the grain size still has some refining. Continuing to increase the content of B so as to make the B/Ti mass ratio exceed 1:2.22, the alloy grain size slowly decline, but the effect is rather poor as a whole. Secondly, the effect of bulk Al5Ti1B master alloy and rod Al5Ti1B master alloy on the grain refining of 6009 wrought alloy prepared with pure Al was investigated. And compared with the effect of AlB master alloy on the grain refinement of 6009 alloy prepared with ELTA (according to B/Ti mass ratio of 1:5 add AlB master alloy). The results indicate that the three methods of titanium addition have all strong refining effect; Comparatively speaking, rod A15Ti1B master alloy has the strongest grain refining capacity on 6009 alloy, secondly bulk Al5Ti1B master alloy, and the grain refining effect of AlB master alloy on 6009 alloy prepared with ELTA among the poor.Thirdly, a comparative study of AlB master alloy on the grain refining of A356 alloy prepared respectively with pure Al and ELTA was investigated. The results indicate that AlB master alloy has good refining effect both on A356 alloy prepared with the two approaches. Furthermore, with the increase of the content of B the grain is continuously refined. When the content of Ti is less than 0.10%, the effect on grain refining of A356 alloy prepared with ELTA has the same level with the alloy prepared with pure AL When the content of Ti is higher, the alloy grain size is larger on the contrary. It shows that Ti added by electrolysis has not obvious effect on A356 alloy which is refined by AlB master alloy.In short, AlB master alloy on the grain refining of Al-Mg-Si wrought alloy prepared with ELTA has excellent effect; this method on A356 casting alloy also acquire good grain refining effect. This process provides a new way of grain refining on wrought alloy.