Page - 133 - in 3D Printing of Metals

Metals 2017,7, 113 input.However, thedepositionof thematerial to thecomponentcan leadto intolerabledistortionof thesheet so that it ispossiblymoreadvantageous touse it toreinforce thesemi-finishedproduct. Figure3.Principleofpowder-based lasercladding. Basicknowledgeabout thepossibilitiesofusingadditivemanufacturingfor localmodification of semi-finished products and components aswell as comparative studies of the properties and economy compared to available solutions are lacking at themoment. Thisworkdetails two case studies investigating thepossibilitiesofferedby lasercladdingfor increasing thesheet thicknessof semi-finishedandformedcomponents. 2.MaterialsandMethods 2.1.Materials The nominal compositions of the materials used are listed in Table 1. As sheet material, the aluminum alloy EN AW 6082 was chosen. As powder material, two similar Al-Si-alloys were chosen that exhibit good performance in laser additivemanufacturing [7]. For both alloys, experience andparameters for laser cladding are available at the Fraunhofer ILT (AlSi10Mg) and BTUCottbus-Senftenberg(AlSi12); therefore,noparameterstudies forcladdinghadtobeconducted. However, it shouldbenotedthat for thedemonstrator II (seeSection2.4)a limitedformabilityof the claddedlayerwill resultdueto thehighSicontent. Thedemonstrator is formedbyahole-flanging operationwithfairlylimitedplasticdeformation. Futureinvestigationswill includewroughtaluminum alloys toallowfor largerplasticdeformation. Table1.Nominalcomposition(wt.%)of thesheetmaterialandthepowder for lasercladding. Materials Si Fe Mn Mg Al SheetENAW6082 0.7–1.3 max. 0.5 0.4–1.0 0.6–1.2 Balance PowderAlSi10Mg 9–11 max. 0.55 max. 0.45 max. 0.45 Balance PowderAlSi12 11–13 notspecified notspecified notspecified Balance 2.2.OverviewofApplicationScenarios Thecasestudies investigated in theremainderof thisworkrepresent twoapplicationscenariosof local reinforcementsandtwodifferentprocesschains: 1. In thefirst case, claddingisappliedto theformedcomponent: the increase insheet thickness improves thestiffnessof thecomponent. In thiscase,asizingoperation (numericaloptimization) needs tobeperformedtodetermine theoptimal thicknessprofile. 133