Fig. 7 — Ti 6-4 near net shaped buildup produced using the CSC (3 pass wide × 1-in.-tall section) and CMT processes (1-in.-wide overhang). crack-sensitive materials that are currently considered to be nonweldable using other arc welding processes such as GTAW. Precise bead placement and the ability to produce nearly spatterfree welds are other attributes that make RWF-GMAW a candidate for building up or repairing narrow surfaces. The buildup shown in Fig. 8 was produced using the CMT process to demonstrate the feasibility of using RWF-GMAW to buildup or repair narrow surfaces. The carbon steel base metal was 1.5 mm wide. A total of five passes were made using a stainless steel wire. A travel speed of 18 in./min was used for each pass along with a calculated heat input of approximately 1 kJ/in. The final buildup height was more than 4 mm. Also, RWF-GMAW has been evaluated for fabricating titanium sheet metal structures. Gas tungsten arc welding was the legacy process for fabricating these structures. Although GTAW produces high-quality welds, it had relatively low deposition rates, and the high heat input causes significant distortion. The RWF-GMAW process is capable of higher deposition rates and lower heat input compared to GTAW, and was evaluated for welding titanium sheet metal structures as a means of increasing productivity and reducing distortion. A photo and macrograph from a Tjoint welded with the CMT process is shown in Fig. 9A, B. Both the web and flange were 1.5 mm thick, and the joint was welded out of chamber using appropriate shielding gas apparatuses. EWI worked with Fronius to develop a custom synergic line for this application. The weld had a very consistent profile, and no spatter was present on the adjacent base metal surfaces. Referring to the macrograph shown in Fig. 9B, the weld had fusion at the root. Conclusions The RWF-GMAW process is a highprecision variation of GMAW that’s capable of producing virtually spatterfree welds with low heat input, low base metal dilution, and precise bead placement. It can produce welds with quality approaching that of GTAW at Fig. 8 — Buildup made on a 1.5-mm-wide carbon-steel surface using the CMT process and a 304 stainless steel wire. APRIL 2015 / WELDING JOURNAL 73
Welding Journal | April 2015
To see the actual publication please follow the link above