双脉冲电弧增材制造数值模拟与晶粒细化机理

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

关键词:  双脉冲电弧|电弧增材制造|数值模拟|晶粒细化

Key words:  double pulsed arc|arc additive manufacturing|numerical simulation|grain refinement

摘要:

电弧增材制造具有成本低和效率高等优点，然而其晶粒细化的研究鲜有报道. 使用自行研制的熔化极气体保护焊电源实施了双脉冲电弧增材制造试验，通过数值模拟预测了晶粒细化现象，试验结果验证了双脉冲电弧的晶粒细化作用. 结果表明，由于熔池的膨胀，熔池尾部出现了重熔化现象. 在与单脉冲电弧热输入相同时，重熔化现象导致双脉冲电弧能够产生更高的冷却速度，并且细化晶粒. 因此，可以通过改变脉冲参数而不是传统地改变热输入来细化晶粒.

Abstract:

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.