Effect of cooling conditions on microstructure and mechanical properties of friction stir welded 7055 aluminium alloy joints
- School of Materials Science and Engineering, Central South University, Changsha 410083 (China)
Highlights: • Water cooling improves tensile properties of friction stir welded 7055 Al alloy. • Water cooling results in smaller grains and second phase in nugget zone. • Water cooling results in finer second phase in thermos-mechanically affected zone. • Water cooling results in finer second phase in heat affected zone. • Fracture surface is flat for air-cooled joint but zig-zag for water-cooled one. - Abstract: The microstructure and mechanical properties of friction stir welded 7055 aluminium alloy under air cooling and water cooling were investigated by means of hardness and tensile testing, optical microscopy and transmission electron microscopy. Water cooling results in reduced softening in the weld zone and therefore higher tensile strength compared to air cooling. Fracture generally occurs within the thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ) on the retreating side in joints welded under air cooling but shifts towards the TMAZ and nugget zone (NZ) in the joints welded under water cooling. The fracture surfaces are generally flat for the air-cooled joint, but exhibits a zig-zag feature for the water-cooled joint. The mechanical behaviour of the weld has been discussed in light of the change in grain structure and precipitation in the NZ, TMAZ and HAZ caused by cooling conditions.
- OSTI ID:
- 22805033
- Journal Information:
- Materials Characterization, Journal Name: Materials Characterization Vol. 141; ISSN 1044-5803; ISSN MACHEX
- Country of Publication:
- United States
- Language:
- English
Similar Records
Defect features, texture and mechanical properties of friction stir welded lap joints of 2A97 Al-Li alloy thin sheets
Effect of Rotation Speed on the Microstructure and Mechanical Properties of Friction-Stir-Welded CuSn6 Tin Bronze