Browsing by Author "Quintino, Luísa"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
Item Open Access Fundamental understanding of the interaction of continuous wave laser with aluminium(Springer, 2017-07-13) Coroado, Júlio; Meco, Sonia; Williams, Stewart W.; Ganguly, Supriyo; Suder, Wojciech; Quintino, Luísa; Assunção, EuricoIn welding, the depth of penetration, weld profile and the corresponding thermal cycle are the three basic outcomes that a user wishes to control flexibly. In laser welding applications, controlled application of power and energy density is the key to achieve predictable control of these characteristics. Creation of an analytical model is an important step towards understanding the underpinning science of laser metal interaction in controlling the depth, bead geometry and thereby temperature profile of a weld. The “power factor model”, which correlates the power applied per unit length to the laser metal interaction time, has been originally developed and validated for mild steel, guides a user on the selection laser system parameters, to achieve specific weld profile. This study is performed to extend the power factor–interaction time model to aluminium alloys by understanding the underpinning laser aluminium interaction parameters in terms of power density, interaction time, specific point energy and their correlation with the weld bead profiles. Although the power factor and interaction time showed a rectangular hyperbolic relationship, as observed in low carbon steel, for a specific weld depth and profile, the absolute magnitude and the characteristic profile of the curve is different due to the intrinsic differences in physical and thermal properties of aluminium as compared to steel. It was shown that identical depth of penetration but different weld metal profile can be obtained for a specific beam diameter for a range of power and travel speed by keeping the energy input per unit length constant.Item Open Access Tandem Metal Inert Gas process for high productivity Wire Arc Additive Manufacturing in stainless steel(Elsevier, 2018-11-19) Martina, Filomeno; Ding, Jialuo; Williams, Stewart W.; Caballero, Armando; Pardal, Goncalo; Quintino, LuísaThis study investigates the feasibility of achieving high deposition rate using wire + arc additive manufacturing in stainless steel to reduce lead time and cost of manufacturing. The pulse MIG welding technique with a tandem torch was used for depositing martensitic stainless steel 17-4 PH. The mechanical and metallurgical properties of the manufactured component were analysed to evaluate the limitations and the extent to which the rate of deposition reaches a maximum without any failure or defect being evident in the manufactured component. Deposition rate of 9.5 kg/hr was achieved. The hardness was matched for the as deposited condition.Item Open Access Welding with high power fiber lasers - A preliminary study.(Elsevier Science B.V., Amsterdam., 2007-01-01T00:00:00Z) Quintino, Luísa; Costa, A.; Miranda, R.; Yapp, David; Kumar, V.; Kong, C. J.The new generation of high power fiber lasers presents several benefits for industrial purposes, namely high power with low beam divergence, flexible beam delivery, low maintenance costs, high efficiency and compact size. This paper presents a brief review of the development of high power lasers, and presents initial data on welding of API 5L: X100 pipeline steel with an 8 kW fiber laser. Weld bead geometry was evaluated and transition between conduction and deep penetration welding modes was investigated.