A Combined Precipitation, Yield Strength, and Work Hardening Model for Al-Mg-Si Alloys

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 41; no. 9; pp. 2276 - 2289
• Main Authors: Myhr, Ole Runar, Grong, Øystein, Pedersen, Ketill Olav
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.09.2010; Springer; Springer Nature B.V
• Subjects: Applied sciences; Characterization and Evaluation of Materials; Chemistry and Materials Science; Exact sciences and technology; Materials Science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metallic Materials; Metals. Metallurgy; Nanotechnology; Structural Materials; Surfaces and Interfaces; Thin Films; Flow Stress; Saturation Stress; Compression Test Data; Total Dislocation Density; Precipitation Model; Precipitation; Aluminium base alloys; Work hardening; Magnesium alloy; Mechanical properties; Yield strength; Microstructure; Precipitation hardening; Modeling; Surface treatment; Strain hardening; Strength
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-010-0258-7

In the present article, a new two-internal-variable model for the work hardening behavior of commercial Al-Mg-Si alloys at room temperature is presented, which is linked to the previously developed precipitation and yield strength models for the same class of alloys. As a starting point, the total dislocation density is taken equal to the sum of the statistically stored and the geometrically necessary dislocations, using the latter parameters as the independent internal variables of the system. Classic dislocation theory is then used to capture the overall stress-strain response. In a calibrated form, the work hardening model relies solely on outputs from the precipitation model and thus exhibits a high degree of predictive power. In addition to the solute content, which determines the rate of dynamic recovery, the two other microstructure parameters that control the work hardening behavior are the geometric slip distance and the corresponding volume fraction of nonshearable Orowan particles in the base material. Both parameters are extracted from the predicted particle size distribution. The applicability of the combined model is illustrated by means of novel process diagrams, which show the interplay between the different variables that contribute to work hardening in commercial Al-Mg-Si alloys.