Effect of annealing on the interface microstructure and mechanical properties of a STS–Al–Mg 3-ply clad sheet

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2012-10, Vol.556, p.319-330
• Main Authors: Lee, Kwang Seok, Yoon, Dong Hyun, Kim, Hye Kyoung, Kwon, Yong-Nam, Lee, Young-Seon
• Format: Article
• Language: English
• Subjects: Aluminum; Aluminum base alloys; Annealing; Applied sciences; Clad metals; Composites; Condensed matter: structure, mechanical and thermal properties; Diffusion layers; Elasticity. Plasticity; Exact sciences and technology; Heat treatment; Interfaces; Magnesium base alloys; Materials science; Mechanical and acoustical properties; Mechanical characterization; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; Physical properties of thin films, nonelectronic; Physics; Production techniques; Stepped; STS–Al–Mg 3-ply sheet; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Tensile properties; Thermomechanical processing
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2012.06.094

In this study we investigated the influence of post-rolling heat treatment upon the microstructure evolution at interface and subsequent uniaxial tensile properties of roll-bonded ferritic stainless steel (STS430)–aluminum (Al3004)–magnesium (AZ31) 3-ply clad metal. By utilizing optical, scanning electron and transmission electron microscopes, the generation and growth of interlayer consists of γ (Mg17Al12) and β (Mg2Al3) phases was verified between the constituent layers in the Mg/Al with total thicknesses of 4.56 and 11.21μm during annealing at 300°C for 1 and 3h, respectively. Although as-rolled clad metal was somewhat joined by mechanical locking at the interface, annealing-induced generation of thin diffusion layer between AZ31 and Al3004 by annealing at 300°C for 1h resulted in the enhancement of uniaxial tensile properties in terms of elongation. However, further annealing for 3h lead to weakening the interface bonding properties due to the significant generation of brittle intermetallic phases. The mechanism for retarding interface delamination along the direction of tensile axis was confirmed by the observation from the side surfaces of ex-situ stepped tensile-test specimens.