The Need

Resistance spot welding (RSW) is critical to automobile manufacturing, with 3,000 to 5,000 spot welds per vehicle. As consumers seek vehicles with better fuel economy, automobile manufacturers have replaced parts built from heavy metals, such as advanced high-strength steel (AHSS), with lighter alloys, such as aluminum (Al) and magnesium (Mg). However, a viable cost-effective solution to fasten dissimilar metals has not been developed.

The Technology

Researchers at The Ohio State University, led by Dr. Wei Zhang, have developed a two-step process that utilizes resistance spot welding and ultrasonic welding to improve the strength of a weld between two dissimilar metals. In the first step, an intermediate joint is created between a steel sheet and an Al foil. In step two, the Al sheet is welded to the steel sheet through the Al foil. The roughened surface of the Al foil creates high electrical contact resistance and thus local heat generation to form the primary joint.

Commercial Applications

• Welding dissimilar metals for manufacturing in the fields of automobiles, aerospace, healthcare, etc.

Benefits/Advantages

• Provides a quick, cost-effective method to fasten dissimilar metals during manufacturing
• Improved primary joint strength for spot welding of two dissimilar metals