Showing papers on "Aluminium alloy published in 2018"

Investigation of Mechanical Properties of Aluminium 6061-Silicon Carbide, Boron Carbide Metal Matrix Composite

Abstract: High demand on materials to increase the overall performance of automotive and aerospace components has forced the development of composite materials. Among the various composites, Aluminium Metal Matrix Composites (AMMC) are widely used to fulfill the emerging industrial needs. This paper deals with the investigation of mechanical properties of AMMC produced by the stir casting technique for various compositions of boron carbide and silicon carbide reinforced with aluminium alloy 6061. The tensile, flexural, hardness and impact tests were performed and it was found that the hybrid composites had better properties than pure aluminium. The microstructure of the hybrid composites was analysed using Scanning Electron Microscopy (SEM).

Control of residual stress and distortion in aluminium wire + arc additive manufacture with rolling

Abstract: The aluminium alloy wire 2319 is commonly used for Wire + Arc Additive Manufacturing (WAAM). It is oversaturated with copper, like other alloys of the precipitation hardening 2### series, which are used for structural applications in aviation. Residual stress and distortion are one of the biggest challanges in metal additive manufacturing, however this topic is not widely investigated for aluminium alloys. Neutron diffraction measurements showed that the as-built component can contain constant tensile residual stresses along the height of the wall, which can reach the materials' yield strength. These stresses cause bending distortion after unclamping the part from the build platform. Two different rolling techniques were used to control residual stress and distortion. Vertical rolling was applied inter-pass on top of the wall to deform each layer after its deposition. This technique virtually elimiated the distortion, but produced a characteristic residual stress profile. Side rolling instead was applied on the side surface of the wall, after it has been completed. This technique was even more effective and even inverted the distortion. An interesting observation from the neutron diffraction measurements of the stress-free reference was the significantly larger FCC aluminium unit cell dimension in the inter-pass rolled walls as compared to the as-build condition. This is a result of less copper in solid solution with aluminium, indicating greater precipitation and thus, potentially contibuting to improve the strenght of the material.

Strengthening mechanisms in ultrasonically processed aluminium matrix composite with in-situ Al3Ti by salt addition

Abstract: Al3Ti reinforced Aluminium composites with different weight percent of Al3Ti particles were developed by in-situ reaction of aluminium alloy with potassium hexafluorotitanate (K2TiF6). Ultrasonication of the aluminium melt during salt reaction was carried out to refine the cast microstructure and achieve better dispersion of in-situ formed Al3Ti particles. The in-situ composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Al3Ti particles generated in the melt promoted heterogeneous nucleation, which was responsible for grain refinement of the cast microstructure. The well dispersed Al3Ti significantly improved the mechanical properties including ductility, yield strength (YS), ultimate tensile strength (UTS) and hardness. The dominant strengthening mechanism in the composite was the thermal mismatch strengthening followed by Hall-Petch strengthening.

Investigation on mechanical properties of aluminium 7075 - boron carbide - coconut shell fly ash reinforced hybrid metal matrix composites

Abstract: The present research work reports the fabrication and evaluation of the mechanical properties of hybrid aluminium matrix composites (HAMC). Aluminium 7075 (Al7075) alloy was reinforced with particles of boron carbide (B4C) and coconut shell fly ash (CSFA). Al7075 matrix composites were fabricated by stir casting method. The samples of Al7075 HAMC were fabricated with different weight percentages of (0, 3, 6, 9 and 12wt.%) B4C and 3wt.% of CSFA. The mechanical properties discussed in this work are hardness, tensile strength, and impact strength. Hardness of the composites increased 33% by reinforcements of 12wt.% B4C and 3wt.% CSFA in aluminium 7075 alloy. The tensile strength of the composites increased 66% by the addition of 9wt.% B4C and 3wt.% CSFA in aluminium 7075 alloy. Further addition of reinforcements decreased the tensile strength of the composites. Elongation of the composites decreased while increasing B4C and CSFA reinforcements in the matrix. The impact energy of the composites increased up to 2.3 J with 9wt.% B4C and 3wt.% CSFA addition in aluminium alloy. Further addition of reinforcement decreased the impact strength of the composites. The optical micrographs disclosed the homogeneous distribution of reinforcement particles (B4C and CSFA) in Al7075 matrix. The homogeneously distributed B4C and CSFA particles added as reinforcement in the Al7075 alloy contributed to the improvement of hardness, tensile strength, and impact strength of the composites.

Effect of energy per layer on the anisotropy of selective laser melted AlSi12 aluminium alloy

Abstract: The anisotropy in the tensile properties of AlSi12 alloy fabricated using selective laser melting (SLM) additive manufacturing process was investigated. The tensile samples were printed in three different orientations, horizontal (H - 0°), inclined (I - 45°), and vertical (V - 90°), and found to exhibit yield strength between 225 MPa and 263 MPa, tensile strength between 260 MPa and 365 MPa, and ductility between 1 and 4%, showing distinct fracture patterns. It was established that the build orientation had insignificant effect on the microstructural characteristics of the SLM-printed samples, while XRD phase analysis showed variations in the Al (111) and Al (200) peak intensities. Consequently, the anisotropy in the mechanical properties of the SLM-printed AlSi12 samples was attributed to the differences in their relative density. Although the energy density was kept constant when printing the samples along different orientations, the “energy per layer” was found to be different owing to the variation in the printing area along the build direction. Further investigation on the effect of printing area, and correspondingly energy per layer, on the relative density was carried out. It was found that energy per layer in the range of 504–895 J yielded ≥99.8% relatively dense AlSi12 SLM-printed samples. This study puts forth a new idea that the density of the SLM-printed samples could be controlled using energy per layer as an input process parameter.

Friction-stir lap-joining of aluminium-magnesium/poly-methyl-methacrylate hybrid structures: thermo-mechanical modelling and experimental feasibility study

Abstract: In this research, the feasibility of friction-stir welding (FSW) for dissimilar lap-joining of an aluminium-magnesium alloy (AA5058) and poly-methyl-methacrylate sheets to attain sound and defect-free joints was examined. The inter-mixing flow patterns between the metal and polymer counterparts during FSW were predicted by employing three-dimensional finite element models. It is shown that the bonding mechanism between the dissimilar materials is mechanical interlocking at the interface which controls the joint strength depending on the processing parameters. The most suitable dissimilar lap-joining regarding microstructural soundness is attained at w= 1600 rev min−1 and v = 25 mm min−1. Under this condition, the maximum joint strength, which is about ∼60% of the weakest base material, is attained. Fractography indicates that the rupture occurs from the aluminium side.

Effect of process parameters on the quality of aluminium alloy Al5Si deposits in wire and arc additive manufacturing using a cold metal transfer process

Abstract: A 3D print device using a cold metal transfer arc welding station to melt a metallic filler wire is developed to build aluminium part by optimising the process parameters. First tests achieved using standard pre-recorded process parameters allow to study the effect of the travel speed and the average welding power on the geometrical characteristics of mono-layer deposits and on walls built by layers superposition. Finally, a parametric study of the effect of each process parameter controlling the shape of the arc current or voltage and the filler wire feeding is carried out in order to try to improve the geometrical regularity of the deposits, and to better understand the effect of each parameter on the melting of the filler wire, its transfer on the support plate, and the geometry of the formed bead.

Optimization of wear parameters and their relative effects on stir cast AA6063-Si3N4 Composite

Abstract: Silicon nitride (Si3N4) is a widely used reinforcement material to improve the mechanical properties of the aluminium matrix composites. Aluminium alloy (AA 6063) matrix composite was produced with different wt% of Si3N4 content through stir casting route. L27 orthogonal array was used to conduct the wear test in Pin-on-disc apparatus. The wear parameters were optimized by S/N ratio and ANOVA analysis. SEM images of the composites show the uniform distribution of Si3N4 particles in AA6063 matrix and its composition was confirmed by EDS analysis. As a result, the minimum wear rate was obtained for the composite contains 10 wt% Si3N4, load of 29.43 N, sliding distance of 1500 m and the sliding velocity of 3 m s−1. ANOVA result reveals that, the weight percentage of reinforcement has the higher percentage of contribution to influence the wear rate of the composite. The confirmation test was conducted and the results are well agreed with optimized parameters.

Correlations between Microstructure Characteristics and Mechanical Properties in 5183 Aluminium Alloy Fabricated by Wire-Arc Additive Manufacturing with Different Arc Modes.

Abstract: The effect of arc modes on the microstructure and tensile properties of 5183 aluminium alloy fabricated by cold metal transfer (CMT) processes has been thoroughly investigated. Heat inputs of CMT processes with three arc modes, i.e., CMT, CMT advance (CMT+A), and CMT pulse (CMT+P), were quantified, and their influence on the formation of pores were investigated. The highest tensile strength was found from samples built by the CMT+A process. This agrees well with their smallest average pore sizes. Average tensile strengths of CMT+A arc mode-built samples were 296.9 MPa and 291.8 MPa along the horizontal and vertical directions, respectively. The difference of tensile strength along the horizontal and vertical directions of the CMT+P and CMT samples was mainly caused by the pores at the interfaces between each deposited layer. The successfully built large 5183 aluminium parts by the CMT+A arc mode further proves that this arc mode is a suitable mode for manufacturing of 5183 aluminium alloy.

Mechanical Properties of Fibre-Metal Laminates Made of Natural/Synthetic Fibre Composites

Abstract: Mechanical properties are among the properties to be considered in designing and fabricating any composite to be used as a firewall blanket in the designated fire zone of an aircraft engine The main focus of this work was to study the tensile, compression, and flexural strengths of the combination of natural/synthetic fibres with metal laminates as reinforcement in a polymer matrix The materials included flax fibres, kenaf fibres, carbon fibres, aluminium alloy 2024, and epoxy The two-hybrid fibre metal laminate composites were made from different layers of natural/synthetic fibres with aluminium alloy of the same thickness The composites were made from carbon and flax fibre-reinforced aluminium alloy (CAFRALL) and carbon and kenaf fibre-reinforced aluminium alloy (CAKRALL) Based on the results obtained from the mechanical tests, the CAFRALL produced better mechanical properties, where it had the highest modulus of elasticity of 44 GPa Furthermore, the CAFRALL was 148% and 204% greater than the CAKRALL in terms of the tensile and compressive strengths, respectively, and it had a 337% lower flexural strength The results obtained in the study shows that both composites met the minimum characteristics required for use in the fire-designated zone of an aircraft engine due to their suitable mechanical properties

Investigation of Mechanical Properties and Dry Sliding Wear Behaviour of Squeeze Cast LM6 Aluminium Alloy Reinforced with Copper Coated Short Steel Fibers

Abstract: LM6 aluminium alloy with 2.5–10 wt% of copper coated short steel fiber reinforced composites were prepared using squeeze casting process. Microstructure and mechanical properties viz., hardness, tensile strength and ductility were investigated. Dry sliding wear behaviour was tested by considering sliding distance and load. Fracture surface and worn surface were examined using field emission scanning electron microscope (FESEM). Hardness of composites increased with increasing wt% of fiber. Tensile strength of composites increased up to 19% for 5 wt% fiber composites. Further addition of fibers decreased the tensile strength of composites. Ductility of the composites decreased with the addition of fibers into the matrix. Wt% of fibers significantly decreased the weight loss, coefficient of friction and wear rate. Also the cumulative weight loss decreased up to 57% for 10 wt% of composites compared to LM6 aluminium alloy. Fracture surface of composite tensile specimen showed dimple formation and fiber pullout. Worn surface of matrix showed long continuous grooves due to local delamination on the surface. However, worn surface of composites showed fine and smooth grooves due to ploughing rather than local delamination. Copper coated steel fiber reinforcement in LM6 aluminium alloy exhibited better mechanical properties and wear resistance compared to matrix.