Résumé
The low carbon steel to 6000 aluminium alloys brazing was investigated by laser and TIG processes. The configuration used in Nd:YAG laser brazing was an overlap one with the aluminium placed upon steel. Two brazing modes were studied, in the first one the joints were obtained between steel and aluminium alloys by reactive wetting whereas in the second mode an aluminium-silicium filler alloy was employed. For TIG brazing the arc was diriged toward steel in a lap configuration where the aluminium was placed upon steel. In the first mode, the brazed joints were realized without filler metal and in the second mode, the influence of silicium, zinc and nickel were studied in powder shape. The joints were observed by optical microscope and scanning electronic microscope. The phase composition was characterized by energy dispersive X-rays and the microhardness was obtained by Vickers hardness test. Two mechanical test were used to characterize fracture strengths of the assemblies. The first one was a transverse tensile test which stressed the interfaces in shearing mode, the second test used was a “tearing off test” which stretched the interfaces in tensile mode. The first results obtained show that that the use of an aluminium-silicium filler reduced the reaction layer thickness for interfaces formed by laser brazing. In the case of reaction layers obtained by TIG brazing, the use of silicium showed a change in morphology with a reduced thickness of the reaction layers. The use of nickel seemed to lower the layer thickness. The fracture strengths of the joints obtained between steel and aluminium without filler metal measured with the transverse tensile test were about 180 N.mm-1 for the joints brazed by laser process and about 140N.mm-1 for the joints obtained by TIG brazing.