A preliminary study on gas metal arc welding-based additive manufacturing of metal parts

Tóm tắt

Introduction: In the past three decades, additive manufacturing (AM), also known as 3D printing, has emerged as a promising technology, which allows the manufacture of complex parts by adding material layer upon layer. In comparison, with other metal-based AM technologies, gas metal arc welding-based additive manufacturing (GMAW-based AM) presents a high deposition rate and has the potential for producing medium and large metal components. To validate the technological performance of such a manufacturing process, the internal quality of manufactured parts needs to be analyzed, particularly in the cases of manufacturing the parts working in a critical load-bearing condition. Therefore, this paper aims at investigating the internal quality (i.e.,
microstructures and mechanical properties) of components manufactured by the GMAW-based AM technology.

Method: A gas metal arc welding robot was used to build a thin-walled component made of mild steel on a low-carbon substrate according to the AM principle. Thereafter, the specimens for observing microstructures and mechanical properties were extracted from the built thin-walled component. The microstructures of the specimen were observed by an optical microscope; the hardness was measured by a digital microhardness tester, and the tensile tests were carried out on a tensile test machine.

Results: The results show that the GMAW-based AMbuilt thin-walled components possess an adequate microstructure that varies from the top to the bottom of the built component: lamellar structures with primary austenite dendrites in the upper zone; granular structure of ferrites with small regions of pearlites at grain boundaries in the middle zone, and equiaxed grains of ferrites in the lower zone. The hardness (ranged between 164±3.46 HV to 192±3.81 HV), yield strength (YS o f f set o f 0.2% ranged from 340±2 MPa to 349.67±1.53 MPa), and ultimate tensile strength (UTS ranged from 429±1 MPa to 477±2 MPa) of the GMAW-based AM-built components were comparable to those of wrought mild steel.

Conclusions: The results obtained in this study demonstrate that the GMAW-based AM-built components possess adequate microstructure and good mechanical properties for real applications. This allows us to confirm the feasibility of using a conventional gas metal arc welding robot for additive manufacturing or repairing/re-manufacturing of metal components