Wire Arc Additive Manufacturing of Al-Mg Alloy with the Addition of Scandium and Zirconium

The proposed paper considers the opportunity of expanding the application area of wire arc additive manufacturing (WAAM) method by means of increasing the strength properties of deposited material, due to the implementation of aluminum wire with the addition of scandium and zirconium. For the experimental research, the welding wire 1575 of the Al-Mg-Sc-Zr system containing 0.23% Sc and 0.19% Zr was selected. The optimal welding parameters, ensuring the defect-free formation of deposited material with low heat input, were used. Porosity level was estimated. The thermal state was estimated by finite element simulation. Simulated thermal state was verified by comparison with thermocouples data. Post-heat treatment parameters that lead to maximum strength with good plasticity were determined. The maximum yield strength (YS) of 268 MPa and ultimate strength (UTS) of 403 MPa were obtained, while the plasticity was determined at least 16.0% in all WAAM specimens.

Effect of Cu Addition on the Precipitation Hardening and Mechanical Properties of Al–Mg Based Cast Alloys

This study examines the formation of different phases of Al-6 mass% Mg–xCu (x = 1 and 3 mass%) alloys in as-cast condition. Further, it investigates the dissolution of these phases upon solution heat treatment (SHT) and studies the precipitation behavior of these ternary alloys. Scanning electron microscopy with energy-dispersive spectrometry and high resolution X-ray diffraction analyses show the presence of the second phases of Al3Mg2 (β), Al6CuMg4 (T), and Al2CuMg (S) in Alloy I (Al–6Mg–1Cu), whereas Alloy II (Al–6Mg–3Cu) had only T and S second phases (with a much higher number of S phases). Upon SHT, a significant number of eutectic phases were dissolved in Alloy I, whereas in Alloy II, the number of undissolved S phases was relatively high. A differential scanning calorimetry (DSC) analysis of experimental alloys in as-quenched states reveals two exothermic peaks related to the formation of nanoclusters and S″ or S′ metastable phases. Both alloys undergo a rapid hardening stage during the aging process, in which approximately 50%–60% of total hardness was achieved. This is attributed to the formation of nanoclusters. The maximum yield strength achieved at the peak hardness condition was approximately 200 MPa for Alloy I, whereas it was approximately 160 MPa for alloy II. Alloy I took a long time to reach peak hardness, which is correlated with the stability of nanoclusters for a longer time. Earlier peak hardness in Alloy II, despite having nanoclusters, is correlated with undissolved eutectic phases acting as heterogeneous nucleation sites for the formation of S″ or S′ metastable phases.

Microstructural Evolution and Mechanical Properties of Graphene-Reinforced Ti-6Al-4V Composites Synthesized via Spark Plasma Sintering

Ti-6Al-4V alloy (TC4) with different concentrations of graphene nanoplatelets (GNPs) were fabricated by ball milling and spark plasma sintering (SPS). Microstructure characteristics of the composites were characterized by X-Ray Diffraction (XRD), Scanning electron microscopy (SEM), and Raman. Microhardness and the compressive mechanical properties were also investigated. Experimental results showed that in the process of SPS, most of the GNPs were still retained at high pressure and temperature, and a new phase of TiC was presented due to the in-situ reaction between TiC and GNPs. Also, the strength of the composites was depended on the concentration of GNPs in TC4 matrix. Consequently, the composite with 0.8 wt. % GNPs was increased 18% in microhardness. The maximum yield strength and ductility of the composite were increased by 22.2% and 43.2%, respectively. The strengthening mechanism of the composites was further discussed, and the Orowan strengthening mechanism was the main strengthening factor.

MICROSTRUCTURAL AND TRANSIENT THERMAL ANALYSIS OF TIG WELDED JOINT SAE 2205 WITH AISI 304 WITH AISI 308 FILLER METAL

In the present work SAE 2205 is welded with AISI 304 using AISI 308 filler wire. TIG welding current was maintained at 110, 120 and 130 Amp and the voltage was set at 40 Volt. A constant welding speed of 0.5 mm/s was maintained for all the experiments. The optical microscopic examination of the welded samples revealed the presence of recrystalized zone, mushy zone at the weld metal SAE 2205 side and columnar grains adjacent to the heat affected zone. The maximum hardness value of Rc 29 was observed in the welded region. The increase in hardness value was attributed to absorption of oxygen in the weld metal during welding and solidification of the weld metal. A maximum yield strength of 354 MPa and an ultimate tensile strength value of 549 MPa were obtained for the samples processed at 130 Amp. Combined transient thermal and stress analysis was performed for the dissimilar stainless steel joints made between SAE 2206 and AISI 304L. A maximum Von Mises stress of 85 MPa was obtained for the weld joints made between stainless steel AISI 304 and stainless steel SAE 2205.

FINITE ELEMENT ANALYSIS OF GO-KART CHASSIS

This paper aims to model, simulate and perform the static analysis of a go-kart chassis consisting of circular beams. Modelling, simulations and analysis are performed using modelling software i.e. SolidWorks for Go Kart Challenges 2017 (GKC-17). The maximum stress and displacement is determined by performing static analysis. The result of maximum stress is compared to maximum yield strength of maximum stress whether the maximum stress is exceeding the maximum yield strength or not. It can also show the displacement where it shows the deformation of the chassis part when the load applied to the chassis. Keywords: chassis; Go kart; FEA; SolidWorks

INTERACTION STRENGTH FOR CHS-TO-LONGITUDINAL PLATE JOINTS UNDER AXIAL LOAD AND IN-PLANE BENDING MOMENT

The circular hollow section (CHS) has lots of advantages in excellent structural properties, architecturally attractive features. Thus, CHSs are used extensively in many applications in buildings, bridges, towers, and offshore. In CHS, it is necessary to understand the various complex shape of CHS joint because loads act simultaneously according to joint type. The use of high-strength steel has been continuously increased, but the current design equation in AISC 2011 or KBC 2016 limits maximum yield strength 360 MPa. This paper studies an interaction strength of high-strength CHS-to-longitudinal plate X-joint subjected to combination of plate axial load and in-plane bending moment. For the study, numerical analysis based on experimental tests was carried out. The analysis was performed according to variables for determining shape of joint, i.e., chord slenderness, plate width-to-CHS diameter ratio, and utilization ratio. Investigations have shown that a linear summation of the ratios for axial load and in-plane bending moment may be used as conservative approximation.

Statics Analysis and Modal Analysis of the Beam Structure of Wave-Maker Based on Finite Element Analysis

In order to achieve lightweighting in the Beam Structure of Wave-maker, it’s necessary to have the statics analyzed for model in the finite element method, results showed that the stiffness and strength have the bigger margin, and it can satisfy design requirements fully, which is the allowable deformation is less than 2 mm, maximum yield strength is less than 325 Mpa. At the same time, in order to get each order modal which the beam, and determine the wave frequency that the need to avoid. Carry on modal analysis of the beam in this paper, results showed that the wave frequency of the wave machine is far less than which each order natural frequency, so the resonance phenomenon caused in the process of work is out of consideration. This research method provides a basis for the design of the beam and optimization.