Study On Grain Refinement Performance Of Al-Ti-B-C Master Alloy On A356Alloy

Nowdays, A356alloy is commonly used to produce wheel hubs in car industry. However, the poor properties, e.g. low elongation, restrict the further development of wheel industry. Grain refinement is the most simple and effective method for A356alloy to improve tensile strength and elongations, which is an urgent problem to be solved. However, the refinement performance of the Al-5Ti-1B and Al-5Ti-0.4C master alloys commonly used in industry can’t fulfill the industrial demand, thus, a new kind of master alloy is urgently needed to improve the tensile strength and elongation, which can effectively refine A356alloy.High scope video microscope (HSVM), X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM) were employed to analyze the microstructure and phase identification of the Al-Ti-B-C master alloy. Refining performance of the master alloy on A356alloy and the mechanism are also discussed. The mechanical properties of A356alloy refined by different master alloys were tested using the CMT4204testing machine and analyzed.The research work in this paper is mainly divided into two parts:(1) Refining performance of the Al-3Ti-1B-0.2C master alloy on A356alloy and refinement ability comparisons among different master alloys.The main second phases of Al-3Ti-1B-0.2C master alloy include TiB2and TiC doped with trace B. The two kinds of particles are well distributed on the Al matrix which can couple with each, thus, providing efficient nucleation sites for α-Al.Comparing with the refinement effect of Al-5Ti-1B、Al-5Ti-0.4C and A1-3B master alloys on A356alloy, Al-3Ti-1B-0.2C master alloy is the most effective. Besides, it does’t disturb the Sr modification effect on eutectic Si. Thus, the Al-3Ti-1B-0.2C master alloy is the most proper candidate as grain refiner for A356alloy, comprehensively.(2) The effect of the rod forming process on the grain refinement of Al-5Ti-0.6B-0.2C master alloy on A356alloy and the grain refinement comparison between rod-like Al-5Ti-0.6B-0.2C and Al-5Ti-1B master alloys. To meet the demand of continuous casting production process, Al-5Ti-0.6B-0.2C ingots need to be squeezed as rods. Through the extrusion process, TiAl3particles change changes from coarse strips to smaller ones, well distributed in the Al matrix.Both the refinement effect and the mechanical properties of the A356alloy refined by rod like Al-5Ti-0.6B-0.2C master alloy are better than that of rod-like Al-5Ti-1B, especially the elongation, exhibiting30.1%increase.