Grain refining technique of AM60B alloy by Al-Ti-B master alloy

摘要

The effects of grain refining parameters on grain size of AM60B magnesium alloy have been investigated using an Al-5Ti-1B master alloy as refiner; and an appropriate refining technique has been developed. The results indicate that the Al-Ti-B master alloy is an effective grain refiner for AM60B alloy and the grain size can be decreased from 348 μm to 76 μm. Raising the addition temperature or the pouring temperature is beneficial for grain refinement; while for the addition amount and holding time, there is an optimal value. The appropriate grain refining technique is that 0.3% Al-Ti-B master alloy is added at 780℃ and then the melt is held for 30 min before pouring. The above phenomena can be explained by the refining mechanisms that have been proposed from the related studies on Al and Mg alloys and theoretical analysis.