Optimization by RSM on rotary friction welding of AA1100 aluminum alloy and mild steel

The objective of this work is to investigate the rotary friction welding of AA1100 aluminum alloy with mild steel, and to optimize the welding parameters of these dissimilar materials, such as friction pressure/time, forging pressure/time and rotational speed. The optimization of the welding parameters was deduced by applying Response Surface Methodology (RSM). An empirical relationship was also applied to predict the welding parameters. Tensile test and micro-hardness measurements were used to determine the mechanical properties of the welded joints. Some joints were analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) in order to investigate the formation of intermetallic compound (IMC) layer at the weld interface. Experimentally, the tensile strength of the weld increases with increasing the forging pressure/time, while the low level of forging pressure/time allows the formation of an IMC layer which reduces the tensile strength of the weld.

Evolution of the Material Microstructures and Mechanical Properties of AA1100 Aluminum Alloy within a Complex Porthole Die during Extrusion

Microchannel tube (MCT) is widely employed in industry due to its excellent efficiency in heat transfer. An MCT is commonly produced through extrusion within a porthole die, where severe plastic deformation is inevitably involved. Moreover, the plastic deformation, which dramatically affects the final property of the MCT, varies significantly from location to location. In order to understand the development of the microstructure and its effect on the final property of the MCT, the viscoplastic self-consistent (VPSC) model, together with the finite element analysis and the flow line model, is employed in the current study. The flow line model is used to reproduce the local velocity gradient within the complex porthole die, while VPSC model is employed to predict the evolution of the microstructure accordingly. In addition, electron backscatter diffraction (EBSD) measurement and mechanical tests are used to characterize the evolution of the microstructure and the property of the MCT. The simulation results agree well with the corresponding experimental ones. The influence of the material’s flow line on the evolution of the orientation and morphology of the grains, and the property of the produced MCT are discussed in detail.

Effects of shoulder geometry of tool on microstructure and mechanical properties of friction stir welded joints of AA1100 aluminum alloy

En este trabajo se estudiaron los efectos de la geometría del hombro de la herramienta en la evolución de la microestructura y las propiedades mecánicas de juntas soldadas de aleación de aluminio AA1100 obtenidos por fricción-agitación usando una máquina fresadora. Tres diseños de hombros se evaluaron con el objetivo de inducir distribuciones diferentes de ciclos térmicos en las regiones de soldadura. Los ciclos térmicos se midieron utilizando termopares y un sistema de adquisición de datos. Caracterización microestructural y análisis cristalográfico de las regiones soldadas se hicieron usando, microscopía óptica y electrónica de barrido, además de difracción de electrones retrodispersados. Las propiedades mecánicas se determinaron por ensayos de tracción, doblez guiado y pruebas de dureza. El comportamiento de la soldabilidad se estableció con base en datos experimentales. Los resultados mostraron que las herramientas con hombro configurado tienen un efecto importante en los ciclos térmicos, generando una amplia región plastificada y el mayor tamaño de grano en la zona de agitación en comparación con la herramienta de hombro plano.

Manufacturing and Characterization of AA1100 Aluminum Alloy Metal Matrix Composites Reinforced by Silicon Carbide and Alumina Processed by Powder Metallurgy

Powder Metallurgy (PM) Techniques consists in a suitable technique to process composites materials. A specific PM technique of mechanical alloying developed to produce new materials in the solid state is a consolidated route to obtain aluminum alloys metal matrix composites. Aluminum alloys metal matrix composites allies the good properties of aluminum and its alloys but with poor mechanical properties and the reinforcement of ceramics phases which add better mechanical properties to these alloys. The research of this materials processing by PM techniques presented new materials with improved properties. In this work an AA1100 aluminum alloy was reinforced by particulate silicon carbide and alumina types of ceramic phases. The powders were mixed and then processed by mechanical alloying in a SPEX vibratory type mill. Then the powders obtained were compacted and vacuum sintered. The sintered composites were characterized by means of Scanning Electron Microscopy (SEM) plus Energy Dispersive Spectroscopy (EDS) and Vickers hardness (HV) tests to evaluate the mechanical behavior.