Le soudage par friction entre l'acier et l'aluminium et l'impact de l'usure de l'outil sur le joint de soudure

Details

Supervisors

Simar, Aude

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil en chimie et science des matériaux, à finalité spécialisée

Abstract

enIn this work, friction welding between aluminium (AA1050 and AA6061) and stainless steel by Friction Melt Bonding (FMB) has been investigated. The wear of the WC-Co tool has been studied as a function of the process parameters. The welds made with a WC-Co tool show large differences in IM layer thicknesses along the weld due to the progressive deformation of the tool. However, the deformation of the WC-Co tool tend to stabilize when it reaches a self-optimized shape. The welds made with a pcBN tool are more homogeneous than with the WC-Co tool since pcBN has a better thermal stability and doesn't deform much. SEM observation and EDS analysis of the IM layer have been made. Two sublayers of distinct IM phases, having a composition similar to FeAl3 and Fe2Al5, have been observed. When the energy input increases, the lower sublayer deteriorates end diffuses inside the aluminium. The occurrence of hot tearing inside the AA6061 reduces the toughness of the joint. The steel sheet undergoes a large plastic deformation during the process. The grains located near the surface are deformed and have a coarse structure. Near the interface, twins are observed inside the grains. The hardness is highest on the surface of the steel, under the tool. The presence of tungsten on the surface has also been detected for the tests made with a WC-Co tool indicating a reaction between the steel and the WC-Co.