Numerical simulation and mechanism study of grain refinement during double pulsed wire arc additive manufacturing

Arc additive manufacturing has the advantages of low cost and high efficiency. However, there are few reports on grain refinement. Double pulsed arc additive manufacturing experiments were carried out by using self-developed gas metal arc welding equipment, grain refinement phenomenon was predicted by using the cooling rate; experimental results also verified the grain refinement phenomenon. Results indicated that remelting phenomenon occurred near the trailing edge due to the expansion of the molten pool. Therefore, double pulsed arc features higher cooling rate and finer grain than conventional single pulsed arc under same heat input. Grain refinement could be achieved by changing pulsing parameters instead of conventionally changing heat input.