Abstract
Adopting the cold metal transfer plus pulse (CMT + P) process, 316L stainless steel wire was treated with a single channel multi-layer deposition experiment under different linear energy. The microstructures of different regions on the deposited samples were observed by optical microscope and scanning electron microscope, and the element distribution in the structure was analyzed by energy dispersive spectrometer. The mechanical properties and microhardness were measured by tensile test method and microhardness tester, respectively, and the anisotropy of tensile strength in horizontal and vertical directions were calculated. Finally, the fracture morphology of the tensile samples were observed by SEM. Experiment results showed that when the difference between the actual and the optimal wire feeding speed matching the specific welding speed was too large, this led to an unstable deposition process as well as flow and collapse of weld bead metal, thus seriously deteriorating the appearance of the deposition samples. The results from metallographic micrograph showed that rapid heat dissipation of the substrate caused small grains to generate in the bottom region of deposition samples, then gradually grew up to coarse dendrites along the building direction in the middle and top region caused by the continuous heat accumulation during deposition. Tensile test results showed that with the increase of linear energy, the horizontal and vertical tensile strength of the as-deposited samples decreased. In addition, the higher linear energy would deteriorate the microstructure of as-deposited parts, including significantly increasing the tendency of oxidation and material stripping. The microhardness values of the bottom, middle and top regions of the samples fluctuated along the centerline of the cross-section, and the values showed a trend of decreasing first and then rising along the building direction. Meanwhile, the yield strength and tensile strength of each specimen showed obvious anisotropy due to unique grain growth morphology. On the whole, the results from this study prove that CMT+P process is a feasible MIG welding additive manufacturing method for 316L stainless steel.
Highlights
Additive manufacturing (AM) is a new technology for manufacturing components by continuously depositing material on the substrate
wire arc additive manufacturing (WAAM) has the advantages over traditional parts manufacturing methods in that it can reduce the waste of raw materials, has better performance, low cost, high molding efficiency [10], and is easy for commercial production
The CMT P process was used to carry out the experiments of single channel multilayer continuous deposition of 316L stainless steel wire, compared to the thin deposited wall study by cold metal transfer plus pulse (CMT+P) process reported in reference [15], we adopted more research samples and more abundant characterization methods to study the effect of the linear energy on the morphology, microstructure, microhardness and tensile mechanical properties of parts, the aim of this paper was to find the optimal linear energy suitable for arc-welding deposition wall by CMT+P through the comparative study of different parameters, which provided a reference for the application of this technology in additive manufacturing
Summary
Additive manufacturing (AM) is a new technology for manufacturing components by continuously depositing material on the substrate. This method is considered as an alternative, cost-effective method for the production of traditional metal components, and can save delivery time and costs [1]. Sci. 2020, 10, 3284 melting (EBM) [8], wire arc additive manufacturing (WAAM) [9], etc. WAAM has the advantages over traditional parts manufacturing methods in that it can reduce the waste of raw materials, has better performance, low cost, high molding efficiency [10], and is easy for commercial production. WAAM has become an important research hotspot all over the world [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
