Advancements in Gas Metal Arc Welding Technology for Improved Silicate Performance
Increasing automotive requirements for improved corrosion life on frames and chassis components have created a challenge for OEMs and suppliers to improve corrosion resistance of painted welds. Lincoln Electric has developed a new weld wire and PPG has created a pretreatment process to properly prepare parts on production lines.
Corrosion resistance linked to the formation of surface silicates or “silicate islands” on the weld surface can cause many issues. These islands consist of multi-component oxides formed during the welding process via chemical reactions between the shielding gas and various deoxidizing elements in the base metal and welding consumable. The impact of these silicate islands on corrosion life stems from their non-conductive nature that interferes with the ecoat process commonly utilized by the automotive industry.
In response to this issue, Lincoln Electric has developed a new solid wire and welding waveform that combine to provide a complete solution for lower surface silicate formation. This new wire utilizes a unique mixture of deoxidizing and surface tension modifying elements to minimize surface silicate formation. The new waveform was developed specifically for the unique chemistry of the wire to improve droplet transfer and deliver a high speed, low spatter, low silicate weld for high volume production.
The purpose of this study was to compare paint adhesion and corrosion resistance of welds made with the new wire versus welds made with an industry standard GMAW wire. The 12 distinct combinations of wire/pre-treatment/coating were tested to 120 cycles of a cyclical corrosion testing.
Learning Station VI: Corrosion and Technology