Effects of Corner Constraint on the Microstructure and Mechanical Properties of Aluminum Alloy Using the CMT+P Deposition Process

Abstract

Wire arc additive manufacturing technology with cold metal transfer and pulse welding (CMT+P) is a promising technology for fabricating complex metal structures. In this paper, a lot of basic research was conducted on the corner-constrained and unconstrained zones of 4043 aluminum alloy made using CMT+P. In particular, the microstructure morphology and mechanical properties of the corner-constrained and unconstrained zones of 4043 aluminum alloy made by CMT+P were studied by using a thermal field emission scanning electron microscope, a microhardness tester, etc. The results showed that there were cellular crystals at the top, columnar dendritic crystals in the middle and bottom, and smaller equiaxed crystals in the bottom center. The grain size in the corner-constrained zone was larger than that in the unconstrained zone, and the grain size increased by about 88.34%. Moreover, the microhardness of the unconstrained zone was 50 HV, while the microhardness of the corner-constrained zone was 45 HV. Furthermore, the tensile strength of this material was 148 MPa, the elongation was 31%, the fracture behavior in the middle and top areas was typical of a ductile fracture, and the fracture in the bottom area was a mixed ductile–brittle fracture dominated by the ductile fracture.