基于冷金属过渡的电弧增材制造钛合金螺旋桨成形机理及组织性能

Study on Forming mechanism, Microstructure and Properties of Titanium Propeller Deposited by CMT

摘要:

通过对基于冷金属过渡(CMT)的电弧增材制造成形过程中电弧形态、电流电压同步信号和熔池形貌的同步检测分析,研究了电弧不同阶段的熔滴过渡形式和熔池金属的受力状态,探明了悬垂结构成形过程中的熔池金属的受力机制,实现了钛合金螺旋桨的成形,并分析成形后的组织性能。研究结果表明,通过对CMT电弧热输入和电弧力的精细控制,能够在无支撑条件下实现螺旋桨叶片的快速成形,同时获得良好的力学性能。在本研究条件下,钛合金CMT增材制造过程中熔滴过渡主要以短路过渡的形式进行,降低基值和短路阶段的焊接电流能够增加悬垂结构倾角,且当I基值/I峰值小于0.3时,钛合金螺旋桨最大倾角达到53.26°。基于优化后的工艺成形船用Ti6321合金,内部组织致密且无贯穿式的粗大柱状晶,力学性能达到同级别锻件标准,水平方向和竖直方向的各向异性不明显。

Abstract:

The forming process of wire and arc additive manufacturing (WAAM) based on the cold metal transfer (CMT) is studied. By monitoring the arc shape, current signal and molten pool shape, the characteristics of droplet and the stress of molten pool metal in different stages of arc are studied. Based on the investigation on the force of the molten pool metal in the forming process of the suspensed structure, the propeller was manufactured and the microstructure and properties were also analyzed. The results show that the rapid prototyping of suspension structure and good mechanical properties can be obtained by precise control of Ibase and Ibase/Ipeak during the CMT process. Under the conditions of this study, the form of short-circuit transfer is the main metal transfer during CMT additive of titanium alloy, and there is no droplet transfer in the peak stage. When Ibase/Ipeak is less than or equal to 0.2, the cantilever structure with large inclination can be obtained by reducing the base current, and the maximum inclination angle of Ti6321 propeller manufactured by CMT process is 53.26°. The Ti6321 alloy fabricated by the optimized overlapping parameters has dense internal structure and no coarse columnar crystals penetrating multiple layers are found in the part. The mechanical properties of the AM parts are the same as the standard of forging, and the anisotropy between horizontal and vertical is not obvious.