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Potential of Resistance Spot Welding Steel to Aluminium Using Inter Layer Transition Materials

Project Code: 23022

Industrial Need

The automotive sector is driven to reduce vehicle weight to achieve present and future performance and emission targets. Many car companies see a multi materials strategy as the best way to achieve weight savings, with a hybrid structure of steel and aluminium being a goal of many automotive producers.

In order to produce a car body rapidly and economically a high speed low cost joining process is required. Over the last 100 years of car production, the fastest, most reliable and lowest cost joining technique has proven to be resistance spot welding. Additionally nearly all car producers have a heavy investment in resistance welding production lines and are familiar with this technology. But the present state of technology does not allow direct resistance spot welding of steel to aluminium. If a solution can be found to allow direct spot welding of steel to aluminium using conventional resistance spot welding equipment, the production of a multi metal car body could become technically feasible and very economic.

The subject of this investigation is to use a third material as an intermediate layer between steel and aluminium plates, to allow the production of high quality spot welds.

Objectives

Design and manufacture transition discs for use in welding trials, identify suitable disc material and geometries for the disc that allow the disc to heat preferentially to the parent materials.

Produce high quality transition joints in two dissimilar materials combinations relevant to the automotive industry.

Assess joint quality and determine if conventional NDT techniques can be applied.

Project Outline

It was proposed to trial a range of commercially available thin sheet (foil) materials as potential inter layers to allow resistance spot welding of automotive grade steel to aluminium. The welds produced were to be qualified against automotive industry acceptance criteria.

Relevant Industry Sectors

Automotive

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