Abstract
Arc brazing has, in comparison to arc welding, the advantage of less heat input while joining galvanized sheet metals. The evaporation of zinc is reduced in the areas adjacent to the joint and improved corrosion protection is achieved. In the automotive industry, lightweight design is a key technology against the background of the weight and environment protection. Structured sheet metals have higher stiffness compared to typical automobile sheet metals and therefore they can play an important role in lightweight structures. In the present paper, three arc brazing variants of galvanized structured sheet metals were validated in terms of the corrosion behavior. The standard gas metal arc brazing, the pulsed arc brazing, and the cold metal transfer (CMT®) in combination with a pulsed cycle were investigated. In experimental climate change tests, the influence of the brazing processes on the corrosion behavior of galvanized structured sheet metals was investigated. After that, the corrosion behavior of brazed structured and flat sheet metals was compared. Because of the selected lap joint, the valuation of damage between sheet metals was conducted. The pulsed CMT brazing has been derived from the results as the best brazing method for the joining process of galvanized structured sheet metals.
Highlights
Galvanized sheet metals have good corrosion resistance to atmospheric corrosion and they are widely used in the automotive industry [1]
The arc brazing advantage is the higher joint strength, which can reach the strength of the base material, and significantly reduced heat input compared to the arc welding
As the curves for each brazing method are practically similar, only the main values were used in the further comparisons for the examination
Summary
Galvanized sheet metals have good corrosion resistance to atmospheric corrosion and they are widely used in the automotive industry [1]. Zinc vapor and zinc oxides lead to pores in the weld metal and an unstable arc behavior [2]. These problems are reduced by bonding or brazing. The technology of cold metal transfer (CMT) is a further development of arc welding and brazing processes, which even more reduces the heat input into the joined components [5, 6]. The corrosion behavior of galvanized structured sheet metals was studied in nonwelded joints in [7, 20]. There is a need to validate the brazed joints corrosion behavior of galvanized structured sheet metals.
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