Welding Galvanized Steel in the Automotive Industry
Improved welding methods to join galvanized steel using cost-effective filler materials are demonstrated By Vlad Tudorache, automotive segment manager, Fronius USA LLC, Portage, Ind. Reprinted with permission: The AWS Welding Journal The high demands of the automotive industry today are challenging, and a solution must be considered when faced with welding applications on coated steels. The specific challenges of welding zinc-coated steels (for example, 60G/60G) are driven by vehicle manufacturers’ expectations of being cost effective while maintaining all necessary conditions for a quality product. Many applications are being joined using robotic gas metal arc welding (GMAW) in combination with different variations of filler materials, such as cored and solid wires including brazing wires when gas metal arc brazing (GMAB) is used. With the cost of these filler materials, ranging from three (in the case of cored wires) to five times (in the case of brazing wires) the amount in comparison to solid wires, it is important to identify new technologies and methods to find better ways of joining coated steels while using cost-effective filler materials, such as solid wires, at increased travel speeds. How a New Technology Works For years, the main “method” to robotically weld coated steels with solid wire successfully was to limit the travel speed at approximately 20–25 in./min. This slower speed allowed for more time to burn off the galvanized coating at the leading edge of the weld pool while reducing the speed of solidification and increased time for degassing of the weld pool. At the same time, this reduced travel speed would limit arc disruption enough that spatter would not become uncontrollable during welding. This production method used pulsed gas metal arc welding (GMAW-P) technology offered by various welding equipment manufacturers. With all that considered, what is the solution where cost-effective filler materials can be used in combination with increased travel speeds and generate an increase in productivity? New advancements in arc technology and welding equipment are trying to answer this question through newly developed advanced pulsed technology and dedicated waveforms. With this technology, travel speeds of 40 in./min can be achieved while using solid wires (for example, ER70S-3) and standard shielding gas mixes (for example, 90/10 Ar/CO2) while satisfying quality requirements for porosity and minimized spatter ejection — Fig. 1.Fig. 1 — Rear axle welded with advanced GMAW-P.
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