Page 54 - MetalForming September 2013
P. 54
Metal-Cored Wire
to prevent burnthrough on thin-gauge material and creates an improved pen- etration profile (Fig. 1); and
• Sufficient arc energy to vaporize the galvanized zinc coating. This allows enough time for zinc vapors to outgas from the weld pool, minimizing the likelihood of porosity in the subsur- face of the weld and on its surface.
Metal-cored wires also feature arc stabilizers that help improve weldmetal transfer from the wire to the weld, min- imizing spatter to help avoid post-weld cleanup.
Controlled Freezing
Combining the use of a metal-cored wire with a pulsed-GMAW waveform also will help control the pace at which the weld pool freezes. This will allow the zinc vapors to escape more readily. In addition, the pulsed-GMAW process inputs less heat into a weldment than does a standard CV process with solid wire, helping to avoid burnthrough.
Fig. 2—Certain levels of porosity (circled) are acceptable in galvanized-steel applica- tions, as depicted in these X-ray images. However, the ability to minimize this porosity while optimizing weld-travel speed will allow metalformers to achieve high quality and productivity.
52
www.metalformingmagazine.com
Other benefits of combining metal-
cored wires for galvanized steels with the pulsed-GMAW process, when weld- ing galvanized steel:
• Improved T-joint and downhill welding;
• A fine ball transfer of weldmetal, which creates a broad arc pattern and
wide weld bead with good gap-bridging ability;
• The ability to weld a wide range of material thicknesses (1.2 to 4.0 mm); and
• The ability to weld in multiple positions. MF
Find new ways to experience WESTEC.
Stay informed with the WESTEC 2013 app. Search
Join the conversation!
Download the app and register today!
800.733.3976 | westeconline.com MetalForming/September 2013
Scan for Android
