Browsing by Subject "aluminum alloy"

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The BCC Unit Cell for Latticed SLM Parts; Mechanical Properties as a Function of Cell Size
(University of Texas at Austin, 2014) Maskery, I.; Aremu, A.O.; Simonelli, M.; Tuck, C.; Wildman, R.D.; Ashcroft, I.A.; Hague, R.J.M.
The existing framework describing the mechanical properties of lattices places strong emphasis on one important property, the relative density of the repeating cells. In this work, we explore the effects of cell size, attempting to construct more complete models for the performance of lattices. This was achieved by examining the elastic modulus and ultimate tensile strength of latticed parts with a range of unit cell sizes and fixed density. The parts were produced by selective laser melting (SLM). The examined cell type was body-centred-cubic (BCC), a cell of high relevance for SLM because of its self-supporting structure. We obtained power law relationships for the mechanical properties of our latticed specimens as a function of cell size, which are similar in form to the existing laws for the density dependence. These can be used to predict the properties of latticed column structures comprised of BCC cells, and may be easily amended for other situations. In addition, we propose a novel way to analyse the elastic modulus data, which may lead to more general models, applicable to parts of varying size. Lastly, our general methodology may be of use in future studies which explore the other parameters that determine lattice performance; the choice of cell type, the global shape of the lattice structure and the type of stress.
Fatigue Performance Enhancement of Selectively Laser Melted Aluminum Alloy by Heat Treatment
(University of Texas at Austin, 2015) Maskery, I.; Aboulkhair, N.T.; Tuck, C.; Wildman, R.D.; Ashcroft, I.A.; Everitt, N.M.; Hague, R.J.M.
We measured the stress-strain behaviour and fatigue performance of the aluminium alloy Al-Si10-Mg manufactured by selective laser melting (SLM). This process, specifically the rapid cooling of the metal from its molten state, results in a fine microstructure, generally providing high hardness but poor ductility. We used a heat treatment to alter the microstructure of the material from its as-built state. This significantly improved the ductility and fatigue performance. The elongation at break for the heat treated material was nearly three times greater than that observed for the as-built material, and the fatigue strength at 106 cycles was around 1.6 times as high. Combined with the design freedoms of additive manufacture, this development increases the suitability of lightweight SLM parts for use in the aerospace and automotive sectors, where good fatigue performance is essential.
Freeform Fabrication of Aluminum Alloy Prototypes Using Laser Melting
(University of Texas at Austin, 2010-09-23) Kyogoku, Hideki; Hagiwara, Masashi; Shinno, Toshifumi
In this study, a direct selective laser sintering/melting machine was designed and constructed. The machine has a 50 W Yb-fiber laser, a galvanometer scanner and a powder delivery and build system. It was confirmed that the machine works well. The fabrication conditions of aluminum alloys were investigated using the machine. The optimum laser power, scan speed and scan pitch were investigated by experiments. The effect of addition of metal powder as additives on laser scanning process was investigated to fabricate the sound laser-scanned body of aluminum alloys based on Al-12Si alloy. It was found that the smooth single-scan track can be fabricated at lower laser power and higher scan speed by the addition of a laser absorption material. An aluminum alloy prototype was successfully produced using optimum laser scanning conditions.
ON PROCESS STABILITY IN WAAM-CMT OF ALUMINUM ALLOYS
(University of Texas at Austin, 2023) Thien, Austen; Kelly, Kathryn M.; Massey, Caroline E.; Saldana, Christopher J.
Wire-arc additive manufacturing (WAAM) has become a cost-efficient metal additive manufacturing process. However, depositing aluminum with WAAM is challenging due to its sensitivity to heat input (linear energy density), which can cause undesirable surface topology waviness if not controlled. Thus, a process window is needed that can produce stable geometry and deposition conditions while minimizing production times. In this study, 5183 aluminum alloy wire is used to deposit 10-layer walls with varying wire feed speeds (WFS) and traverse speeds (TS) (at a constant WFS/TS ratio) and varying interpass temperature (IPT). In-situ process data consisting of optical contact-tip-workpiece-distance (CTWD) and current/voltage measurements are collected to determine process condition stability throughout the build. Part geometry is measured using a 3D scanner and build porosity is characterized via digital X-ray. A process window is identified that produces stable surface topology and process conditions at a minimal production time.
Quantitative Evaluation of Crystallographic Texture in Aluminum Alloy Builds Fabricated by Very High Power Ultrasonic Additive Manufacturing
(University of Texas at Austin, 2012) Sojiphan, K.; Babu, S.S.; Yu, X.; Vogel, S.C.
Very high power ultrasonic additive manufacturing (VHPUAM) has shown good bond quality over traditional ultrasonic consolidation processes. However, the stability of microstructure in bulk and interface regions is unknown. Our earlier research showed a large difference in grain growth kinetics between bulk and interface regions. Therefore, we have performed in-situ studies of crystallographic texture evolution using a neutron beam line, before, during, and after heat treatment at 343oC for 2 hours. Shear texture in the as-received condition was found to be stronger with higher vibration amplitudes. We also observed rapid reduction of rolling textures in the initial material and presence of shear textures even after heat treatment.
Small-Scale Characterization of Additively Manufactured Aluminum Alloys Through Depth-Sensing Identification
(University of Texas at Austin, 2018) Alghamdi, F.; Verma, D.; Haghshenas, M.
Selective laser melting (SLM) can be considered as a suitable additive manufacturing method for printing complex-in-shape aluminum components. However, to adopt the SLM for mass production of aluminum components for automotive and aerospace applications, one needs to fully understand the correlations between the SLM parameters, produced microstructure, and local mechanical properties of the printed parts. In this paper, along with microstructural assessments (optical and scanning electron microscopy), small-scale properties of two additively manufactured aluminum alloys, AlSi10Mg and A205.0, were examined using an instrumented (depth-sensing) indentation testing technique. An instrumented indentation testing approach is a semi-destructive, reliable and convenient method which enables us to study the variations and distributions of the mechanical properties (i.e. hardness) as a function of distance from the build plate. The variations in properties are then compared in AlSi10Mg and A205.0 alloys and are correlated to the generated microstructures in the printed alloys.