Effect of heat treatment on tensile and fatigue deformation behavior of extruded Al-12 wt%Si alloy

• Published in: Metals and materials international 2017, 23(1), , pp.35-42
• Main Authors: Ham, Gi-Su, Baek, Min-Seok, Kim, Jong-Ho, Lee, Si-Woo, Lee, Kee-Ahn
• Format: Article
• Language: English
• Subjects: Alloys; Aluminum alloys; Aluminum base alloys; Behavior; Characterization and Evaluation of Materials; Chemistry and Materials Science; Cycle ratio; Deformation; Deformation analysis; Deformation effects; Engineering Thermodynamics; Extrusion; Fatigue failure; Fatigue limit; Fracture surfaces; Grain size; Heat and Mass Transfer; Heat treating; Heat treatment; High cycle fatigue; Intermetallic compounds; Intermetallics; Machines; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Mechanical properties; Metal fatigue; Metallic Materials; Microstructure; Phases; Powder metallurgy; Processes; Silicon; Solid Mechanics; Spray forming; Surface analysis (chemical); Ultimate tensile strength; Water quenching; 재료공학
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-017-6351-3

This study investigated the effect of heat treatment on tensile and high-cycle fatigue deformation behavior of extruded Al-12 wt%Si alloy. The material used in this study was extruded at a ratio of 17.7: 1 through extrusion process. To identify the effects of heat treatment, T6 heat treatment (515 °C/1 h, water quenching, and then 175 °C/10 h) was performed. Microstructural observation identified Si phases aligned in the extrusion direction in both extruded alloy (F) and heat treated alloy (T6). The average grain size of F alloy was 8.15 °C, and that of T6 alloy was 8.22 °C. Both alloys were composed of Al matrix, Si, Al 2 Cu, Al 3 Ni and AlFeSi phases. As T6 heat treatment was applied, Al 2 Cu phases became more finely and evenly distributed. Tensile results confirmed that yield strength increased from 119.0 MPa to 329.0 MPa, ultimate tensile strength increased from 226.8 MPa to 391.4 MPa, and the elongation decreased from 16.1% to 5.0% as T6 heat treatment was applied. High-cycle fatigue results represented F alloy’s fatigue limit as 185 MPa and T6 alloy’s fatigue limit as 275 MPa, indicating that high-cycle fatigue properties increased significantly as heat treatment was conducted. Through tensile and fatigue fracture surface analysis, this study considered the deformation behaviors of extruded and heat treated Al-Si alloys in relation to their microstructures.