Browsing by Author "Rodrigues, J.P."

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    An Experimental Investigation on Microstructure, Mechanical Properties and Corrosion Performance of CMT-Wire Arc Additively Manufactured Al-4043 Alloy
    (Springer, 2023) Manjhi, S.K.; Kumar, B.S.S.; Rodrigues, J.P.; Sekar, P.; Bontha, S.; Balan, A.S.S.
    The wire arc additive manufacturing process (WAAM) has drawn incredible potential to manufacture non-ferrous alloys such as Aluminium and Magnesium. The deposition of Aluminium using a conventional WAAM process resulted in various defects such as porosity, cracks and tensile residual stress owing to high heat input. Therefore, to address these challenges, cold metal transfer wire arc additive manufacturing process (CMT-WAAM) is used to deposit 4043 Al alloy. The microstructure, mechanical properties and corrosion performance of Al 4043 are evaluated to ascertain the quality of deposited parts. The XRD peak intensity and microstructure shows that the main phases are α-Al and MgSi2 eutectics distributed along the grain boundaries of the Al matrix. The grain size of the bottom section is relatively smaller than the middle and top sections due to the high thermal gradient at the beginning of the deposition. Therefore, the hardness increases from the bottom to the top section of the thin wall. In addition, variations in the fraction of secondary phases are also responsible for the variation in hardness. The average UTS and % EL of travel direction (TD) are 177 ± 5 MPa and 20 ± 0.3%, which are relatively higher than the average UTS (164 ± 2 MPa) and % EL (17 ± 0.5%) of build direction (BD). However, the differences are only 10 ± 3 MPa and 2 ± 0.3% EL, exhibiting isotropic mechanical properties. The corrosion rates of the bottom, middle and top sections are 0.172, 0.116 and 0.102 mm/year, which are comparable, exhibiting uniform corrosion resistance of the deposited thin wall. © 2023, The Indian Institute of Metals - IIM.
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    Hybrid additive manufacturing of ER70S6 steel and Inconel 625: A study on microstructure and mechanical properties
    (Elsevier Ltd, 2023) Rodrigues, J.P.; Thanumoorthy, R.S.; Manjhi, S.K.; Sekar, P.; Arumuga Perumal, D.A.; Bontha, S.; Balan, A.S.S.
    Hybrid Additive Manufacturing (HAM) is currently being explored because of its potential to achieve trade-off between build capacity and feature resolution. The present study aims at fabricating ER70S6-Inconel 625 (IN625) bimetallic clad using hybrid Wire Arc Additive Manufacturing (WAAM) and Laser Directed Energy Deposition (LDED) processes. Microstructure evaluation was performed at the cross section of bimetallic clad for distinct materials as well as the interface. WAAM built ER70S6 revealed equiaxed ferritic grains, whereas laser deposited IN625 region showed columnar dendrites with under developed secondary arms. However, the first layer of IN625 exhibited columnar dendrite with secondary arms due to the influence of diffused Fe from the base ER70S6 steel under the action of concentrated laser heat source, which was revealed by energy dispersive spectroscopy (EDS) maps. The measured microhardness across the cross section of the deposit showed values corresponding to inherent material system. The interface did not reveal presence of any intermetallic phases which was confirmed by hardness results and X-Ray diffraction. Shear test revealed superior bond strength between the two materials, maintaining average strength of 452 MPa. The fractography images exhibited fine dimples along with cleavages indicating mixed fracture characteristics. This additive manufacturing method explores a new dimension in multi-material fabrication which, when customized for different materials, serve critical areas in the aerospace and defence sector. © 2023 Elsevier Ltd