• Van Hooreweder, Brecht
• Simar, Aude
• Delmée, Maxime
• Gheysen, Julie
• Nothomb, Nicolas

Abstract

One of the main drawbacks of Laser Powder Bed Fusion (L-PBF) is the limited materialpalette currently available and the often poor fatigue performance of the resulting parts.Currently, the only high-performance aluminium alloy used to produce parts adapted for theaerospace industry using L-PBF is the Scalmalloy. However, it contains Sc, a scarce andexpensive alloying element. L-PBF does not yet allow the production of such parts usingmore conventional 7xxx aluminium alloys. Indeed, these alloys exhibit severe cracking dueto the high thermal gradients during L-PBF process.One way of suppressing hot cracking consists in the addition of grain refiner to the initialpowder. In this study, a micrometric ZrH2 powder was added to Al7075 commercial prealloyedpowder by the means of two different methods: a classical mechanical mixing and aninnovative plasma coating. L-PBF process parameters were optimised and dense crack-freesamples were produced. The microstructure and tensile properties for both additiontechniques were thoroughly analysed and compared. A heat treatment leading to similarmechanical performances as the wrought Al7075 is currently being optimised. A firstcharacterisation of the fatigue properties of these heat-treated L-PBF alloys and theirimprovements using friction stir processing as post-treatment are being assessed. Indeed,friction stir processing has been proven as a very successful post-processing method toincrease the fatigue life of AlSi10Mg by a factor 100 [1].

Topics

• impedance spectroscopy
• grain
• aluminium
• crack
• fatigue
• aluminium alloy
• selective laser melting
• mechanical mixing