Deposition process and mechanical properties of magnesium alloy inclined thin-walls fabricated by wire-arc additive manufacturing

Abstract

Wire-arc additive manufacturing is a new type of manufacture using wire as filling material and arc as a heat source， making it easier to manufacture complex-shaped and big-sized parts. The reciprocating and unidirectional process path experiment was conducted. The inclined wall made by unidirectional path has better morphology， less splash， and a smoother surface. The simulation model of AM11 reciprocating and unidirectional manufacturing path was established in finite element software and solved. The simulation results show that the unidirectional path deposition temperature is 267.4 ℃， the deposition thermal stress is 357.4 MPa， the reciprocating path deposition temperature is 307.0 ℃， and the deposition thermal stress is 420.4 MPa， the heat accumulation and thermal stress of unidirectional path are lower than that of reciprocating path. AM11， AM12， and AM21 inclined wall samples with different slope factors by wire-arc additive manufacturing in unidirectional path were prepared， and their microstructure and properties were analyzed. The results indicate that the grain size of AM11， AM12， and AM21 is 35， 39 μm， and 42 μm， there is more precipitated β-Mg17Al12 in AM21 thin-walled grains， which has larger and more dimples than that of the other two samples. The micro-hardness values of AM21 and AM11 are both about 81.5HV， higher than 73.1HV of AM12. The horizontal and vertical tensile strengths of the AM21 inclined wall sample are 255.7，224.4MPa， the yield strengths are 103.8，96.0 MPa， and the elongations reach 13.1% and 8.2%. The tensile strengths and elongations are both greater than those of AM11 and AM12 samples， but the yield strengths are close. The AM21 inclined wall has much better strength and plasticity， and verify that the more perpendicular the inclined wall of magnesium alloy arc additive manufacturing is， the better the mechanical properties such as strength and plasticity.

Keywords

• wire arc additive manufacturing
• az91d magnesium alloy
• thin-walled part
• microstructure
• mechanical property
• fracture morphology