Peter Nerman, Elisabeth Öhman

Abstract

In recent years, different brazing processes have gained more interest as an alternative to fusion welding in the manufacturing industry. The most interesting field of applications here seems to be automotive body components manufactured of thin zinc coated steel.

As a part of a bigger project at SIMR – JTC a literature study has been performed in order to compare arc- and laser brazing processes with corresponding fusion welding processes. A special focus has been set on thin steel sheet materials and automotive applications. Induction, vacuum, resistance and furnace brazing has therefore not been studied.

The results from the study show that both arc brazing and laser brazing can be a good alternative to conventional fusion welding of thin steel sheets. Brazing is reported to be advantageous in joining of zinc coated steel sheets where the use of conventional fusion welding can be limited and/or costly.

Most materials that can be fusion welded can also be brazed with equal or better results. The low heat input, compared to conventional fusion welding, causes less metallurgical problems and less problems with distortion of the base metal.

There are also disadvantages with brazing compared to conventional fusion welding. The demand for clean surfaces, free from dirt and oxides, are greater compared to conventional fusion welding.

Regarding the brazing process, it must be noticed that all common processes used for conventional fusion welding can also be used for brazing. MIG/MAG seem however to be the most common process for arc brazing which is probably due to the low cost for the equipment and the fairly easy implementation in the existing production system.

It is interesting to notice that all brazing processes studied in this work seem to have a very high productivity compared to conventional fusion welding. Welding speeds of 3 m/min have been reported for both MIG/MAG and laser brazing. Regarding the quality of the finished joint, it seems that plasma and laser brazing have the best potential.