WELDING RESEARCH tion of the cladding by the substrate. Dilution can have a significant effect on the performance of the cladding. For corrosion resistance applications, the corrosion performance of some cladding can be rather sensitive to the change in dilution. For wear resistance applications, dilution can affect the severity of cracking encountered. For erosion plus corrosion applications, cracking of the hardfacing alloy can provide a corrosion path to the substrate. Hence, a two-layer cladding may help, with the first layer being the corrosion resistant alloy and the second layer being the hardfacing alloy. A crack-free hardfacing alloy may also help in some cases. The present study used GMAWCSC and 1.6-mm PolyTung NiBWC cored welding wire to make the cladding. However, it differed from the study of Vespa et al. (Ref. 3) in several ways. First, conventional GMAW was also used and the results were compared with those of GMAWCSC. Second, instead of just singlebead cladding, a 3D printer-based substrate manipulation table was built to make the cladding over a square area, both single layer and multiple layers. Third, the overall composition of the cladding was measured. Fourth, the effect of Cr on WC dissolution was shown by thermodynamic analysis. Experimental Procedure Materials The workpiece was 1018 steel, 150 mm long, 50 mm wide, and 6.4 mm thick. Single-bead welding was conducted in the length direction along the centerline of the workpiece, at the travel speed of 15 mm/s and various heat inputs. The filler metal for depositing the cladding was a Poly- Tung NiBWC flux cored wire of 1.6- 452-s WELDING JOURNAL / DECEMBER 2016, VOL. 95 Fig. 1 — 3D printer (lower left corner) supporting and generating 3D motion of the steel workpiece under the welding gun to allow printing filler metal on steel. of PolyTung NiBWC (Ref. 5) Table 1 — Nominal Chemical Composition (wt%) W Si B Ni Wt% 38–45 2.2 1.0 Balance Table 2 — Welding Parameters for Conventional GMAW Samples Welding Feeding Traveling Speed Electrode Extension Heat Input Gas Flow Rate Shielding Gas Voltage (V) Speed mm/s mm/s (mm) (J/mm) (m3/h) 52 18 29.6 15 22.5 99.5 1.1 75% Ar 25% CO2 53 19 29.6 15 22.5 107 1.1 75% Ar 25% CO2 54 20 29.6 15 22.5 111 1.1 75% Ar 25% CO2 55 21 29.6 15 22.5 120 1.1 75% Ar 25% CO2
Welding Journal | December 2016
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