Comparative Multi-Modal, Multi-Scale Residual Stress Evaluation in SLM 3D-Printed Al-Si-Mg Alloy (RS-300) Parts

Eugene S Statnik,Alexander M Korsunsky,Yuliya V Malakhova,Svetlana A Lipovskikh,Yuliya V Kan,Dmitry K Ryabov,Alexey I Salimon,Pavel A Somov,Fatih Uzun,Aleksandr G Seferyan,Vladimir S Pisarev,Sviatoslav I Eleonsky

doi:10.3390/met11122064

Eugene S Statnik, Alexander M Korsunsky + Show 10 more

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https://doi.org/10.3390/met11122064

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Abstract

SLM additive manufacturing has demonstrated great potential for aerospace applications when structural elements of individual design and/or complex shape need to be promptly supplied. 3D-printable AlSi10Mg (RS-300) alloy is widely used for the fabrication of different structures in the aerospace industry. The importance of the evaluation of residual stresses that arise as a result of the 3D-printing process’ complex thermal history is widely discussed in literature, but systematic assessment remains lacking for their magnitude, spatial distribution, and comparative analysis of different evaluation techniques. In this study, we report the results of a systematic study of residual stresses in 3D-printed double tower shaped samples using several approaches: the contour method, blind hole drilling laser speckle interferometry, X-ray diffraction, and Xe pFIB-DIC micro-ring-core milling analysis. We show that a high level of tensile and compressive residual stresses is inherited from SLM 3D-printing and retained for longer than 6 months. The stresses vary (from −80 to +180 MPa) over a significant proportion of the material yield stress (from −⅓ to ¾). All residual stress evaluation techniques considered returned comparable values of residual stresses, regardless of dramatically different dimensional scales, which ranged from millimeters for the contour method, laser speckle interferometry, and XRD down to small fractions of a mm (70 μm) for Xe pFIB-DIC ring-core drilling. The use of residual stress evaluation is discussed in the context of optimizing printing strategies to enhance mechanical performance and long-term durability.

Highlights

This means that the permanent inelastic strains that act as the sources of residual stress are distributed within a prismatic body of extrusion as a function of the transverse coordinates only
The results show that the calculations of the contour method solution provide a good match with FIB-DIC evaluations of the xcomponent of residual stress in both real and continuous geometry models, but the quantity and quality of experimental measurements should be increased in order to state that all direct components of residual stress can be calculated reliably using the present approach
The residual stresses formed during additive manufacturing are dependent on the model geometry even under nominally identical 3D-printing conditions, albeit in indirect ways associated with the change of cross-section, the presence of supports, and the filling ratio, which strongly affect the thermal flux conditions and thermo-mechanical gradients

Summary

Introduction

Selective Laser Melting (SLM) 3D-printing as a technology of rapid fabrication of net shape or near-net shape metal parts for various applications has matured in last 20 years and reached the stage of readiness for mass-production. In this context, issues of quality stability and service life management have become the principal focus of further development. Issues of quality stability and service life management have become the principal focus of further development This is especially important for 3D-printable Ti, Ni, and Al alloys that have recently began to see increasing use in the aerospace domain [1,2,3].

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