Identification of AlSi10Mg matrix behavior by nanoindentation

Anne Marie Habraken,Anne Mertens,Chantal Bouffioux,Hoang Son Tran,Juan Guillermo Santos Macías,Olivier Dedry

doi:10.25518/esaform21.2464

Abstract

Laser powder bed fusion (LPBF) is an additive manufacturing technique that is widely used to produce AlSi10Mg parts with a good strength-to-weight ratio and a very fine microstructure thanks to high cooling rates. However, to obtain better mechanical properties, a good ductility and higher fatigue resistance, post-treatments have to be performed. In this work, friction stir processing, a thermomechanical post-treatment, is applied on an as-built plate of 5 mm of thickness. This post-treatment leads to a decrease of the percentage of porosities and to modification of the microstructure: globularized Si-rich particles are surrounded by the α-Al phase. The method presented uses nanoindentation to determine the behavior of the different phases present in the material for future numerical simulations and a better understanding of the relation between microstructure and fatigue strength. The Bucaille method [1] is used to determine the links between indentation curves and elastoplastic parameters. Three different pyramidal indenters are used: Berkovich, cube corner and an indenter with a centerline-to-face angle of 50 degrees. From the loading / unloading curves and after post-processing, the Young's modulus, the representative strain and the associated stress are determined. With the three different indenters and their three true stress/true strain points, a good description of the elastoplastic behavior can be defined.

Highlights

Additive manufacturing of metal parts is becoming more and more widespread because it allows greater part design optimization compared to conventional manufacturing techniques [2]
In order to obtain better mechanical properties, good ductility and higher fatigue resistance, post-treatments have to be performed. While these are generally heat treatments, the post-treatment used in this article, friction stir processing (FSP), is of the thermomechanical type
The Young's modulus obtained from the two grids and from the indentations made with the cube corner are Identification of AlSi10Mg matrix behavior by nanoindentation compared with the value obtained from four tensile tests

Summary

Introduction

Additive manufacturing of metal parts is becoming more and more widespread because it allows greater part design optimization compared to conventional manufacturing techniques [2]. This optimization results in weight savings that are highly appreciated in many fields, in the aerospace and automotive industries [3]. In order to obtain better mechanical properties, good ductility and higher fatigue resistance, post-treatments have to be performed While these are generally heat treatments, the post-treatment used in this article, friction stir processing (FSP), is of the thermomechanical type. The advantage of this post-treatment compared to the usual heat treatments is to decrease the percentage of porosities, which improves the fatigue properties [6]

Methods

Results

Conclusion