Influence of the Thickness of the Reaction Zone in Aluminum/Stainless Steel Brazed Joints on the Mechanical Properties

Abstract

The study deals with the characterization of the relationship between the microstructure of the reaction zone and the mechanical properties in the brazed joints of aluminum alloy 3003 and stainless steel AISI 304 in order to determine the influence of the intermetallic layers on the tensile shear strength of the joints. The joints were produced by induction brazing using an AlSi10 filler in an argon atmosphere at a temperature of 600 °C. Due to the local heat input into the liquid brazing filler during a short brazing time, a thin reaction zone is formed in the brazed joints (~1 µm), which ensures good mechanical properties of the joints. In order to observe the growth kinetics of the reaction zone in the brazed joints and to investigate the influence of the thickness of the reaction zone on the mechanical properties of the brazed joints, the joints were aged at temperatures of 200 °C and 500 °C for 6, 48 and 120 h. The results have shown that the thickness of this layer increases to a maximum of 2 µm depending on the duration of the thermal aging at a temperature of 200 °C. The results of the tensile shear strength tests have shown that the brazed joints with this thin layer ensure a high strength. The thermal aging at a temperature of 500 °C influences the growth of the reaction zone in the brazed joints significantly. The total thickness of the reaction zone increases to a maximum of 12 µm during the thermal aging. The results of the tensile shear tests of these joints have shown that the thermal aging at a higher temperature leads to a decrease of the tensile shear strength of the brazed joints to 67% due to the growth of the existing intermetallic layer and the formation of a new intermetallic layer in the reaction zone.

Development of Rapidly-Quenched Al-Ge-Si Filler Alloys for the Joining of Stainless Steel AISI 304 and Aluminum Alloy AA6082

“…Aluminum alloys are widely used in the automotive, aerospace, and electronics industries [1][2][3]. The task of reducing the weight of vehicles and aircraft through the use of lighter materials is caused by the desire to save fuel, economic benefits, and the environmental agenda [4]. In the automotive industry, aluminum alloys are used as radiator materials for heat dissipation devices, cylinder blocks, car body cladding, and so on [5][6][7].…”

Joining of Aluminum and Steel using AlSi12 Brazing Filler in a Protective Atmosphere Furnace: Microstructure and Mechanical Properties

“…It was reported that the formation of IMCs phases is highly dependent on thermal impacts, such as temperature and holding time, during the joining process. The IMCs layers at the interface adjacent to the steel are generally considered to be the main cause for the mechanical degradation of the joints [1][2][3][4][5][6][7][8][9][10] . It is of general interest to minimize the thickness of IMC phases at the joint interface by metallurgical methods and/or by the application of low interaction temperatures and short times to limit reaction and interdiffusion.…”

“…Up to now, there are a few reports on the brazing of Al alloys to steel/stainless steels by means of furnace brazing, vacuum brazing or even in air using flux for brazing. However, most of reported work were focused on the joining between Al alloys and stainless steel [1][2][3][6][7][8][9][10] , there is few reports on the brazing of pure Al to steels [4,5] which is one of the main joints of STJ.…”