Abstract: Al/steel bonding castings was manufactured by the molten aluminum and explosively welded Cu/steel plate. Crack initiation and propagation at Al/steel interface were investigated by SEM in the as-cast condition as well as in specimens which were heated at various temperatures and then air-cooled. The main cracks are found in the Fe2Al5 continuous intermetallic layer at the ridges of the wavy Al/steel interface and most of these cracks are parallel to the wavy interface. Being heated at different temperatures from 300℃ to 600℃, and then air-cooled, these cracks propagate from ridges to the vales and peaks, and also appear in FeAl3 blocks as well. Most of these cracks are found to be parallel to the wavy interface too. The residual stress due to different thermal expansion coefficients of the interacting phases and the volume change effect associated with the formation of intermetallic compounds, is suggested to be responsible for the crack initiation. Kirkendall effects during the formation of Fe2Al5 result in amounts of tiny holes in this layer, which might facilitate the crack initiation and propagation afterwards.
Crack initiation and propagation at Al/steel interface in castings produced by molten aluminum and explosively welded Cu/steel plate
Abstract:
Al/steel bonding castings was manufactured by the molten aluminum and explosively welded Cu/steel plate. Crack initiation and propagation at Al/steel interface were investigated by SEM in the as-cast condition as well as in specimens which were heated at various temperatures and then air-cooled. The main cracks are found in the Fe2Al5 continuous intermetallic layer at the ridges of the wavy Al/steel interface and most of these cracks are parallel to the wavy interface. Being heated at different temperatures from 300 ℃ to 600 ℃, and then air-cooled, these cracks propagate from ridges to the vales and peaks, and also appear in FeAl3 blocks as well. Most of these cracks are found to be parallel to the wavy interface too. The residual stress due to different thermal expansion coefficients of the interacting phases and the volume change effect associated with the formation of intermetallic compounds, is suggested to be responsible for the crack initiation. Kirkendall effects during the formation of Fe2Al5 result in amounts of tiny holes in this layer, which might facilitate the crack initiation and propagation afterwards.