Distortion Analysis of SLM Product of SS316L using Inherent Strain Method

Abstract

As one of additive manufacturing (AM) technologies, selective laser melting (SLM) which uses higher energy input enabling fully molten powder bed materials is nowadays increasingly applied to build full dense components without post processing. In the present work, specimens made of stainless steel powder SS 316L were to be processed using SLM Solutions 280 HL, characterized and compared to the simulation from Finite Element Analysis (FEA) Software. The powders have been melted to produce cantilever specimens with different build orientation by using fixed major process parameters such as laser power, hatching distance and layer thickness as well as scan speed. The experiment starts with the FEA simulation which focused on Inherent Strain Method (ISM) and followed by experimental process. While the distortion of the specimens after the process to be the main concern and to be discussed based on the build orientation of the specimens. The measurement distortion of the specimens was conducted by using KEYENCE 3D scanner. It is found out that the build orientation play a big role on distortion of the specimens made from SLM. Meanwhile, result of distortion from the experiment and FEA simulation are close to each other. It is expected that this basic FEA study will provide basic information and estimation towards the distortion and computational time by simulating product prior to commencement of real product manufacturing. Thus, by using ISM will reduce the computational time and reduce the waste material by simulating the process before the experiment have been held.

The inherent strain method for simulation of additive manufacturing–A critical assessment based on a new variant of the method

“…This definition is consistent with the linear IS method (cf set of Equation 2), and it is used by many other authors: Yaghi et al, 11 Bugatti and Semeraro, 17 Jonsson and Krappedal, 18 Munro et al, 19 Siewert et al, 20 Taufek et al 21 To identify the inherent strain tensor $$$ {\boldsymbol{\upvarepsilon}}^{\ast } $$$, different methods can be found in the literature. They are listed hereafter, according to the classification introduced in the Introduction Section.…”

“…The identification consists then in the following minimization problem: $$$$ {\boldsymbol{\upvarepsilon}}^{\ast }=\mathrm{argmin}\ \left\Vert {\mathbf{u}}^{sim}\left({\boldsymbol{\upvarepsilon}}^{\ast}\right)-{\mathbf{u}}^{exp}\right\Vert $$$$ where $$$ {\mathbf{u}}^{exp} $$$ denotes a set of experimental measurements of distortions, while $$$ {\mathbf{u}}^{sim}\left({\boldsymbol{\upvarepsilon}}^{\ast}\right) $$$ denotes the corresponding predictions by IS simulation. This method was used by Jonsson and Krappedal, 18 Setien et al, 16 Siewert et al, 20 Lu et al, 22 Taufek et al 21 …”

“…where u exp denotes a set of experimental measurements of distortions, while u sim (𝛆 * ) denotes the corresponding predictions by IS simulation. This method was used by Jonsson and Krappedal, 18 Setien et al, 16 Siewert et al, 20 Lu et al, 22 Taufek et al 21 2.2.2 Small-scale specimen and identification based on simulation only (class 2)…”

Study on the Milling of Additive Manufactured Components

“…The starting material was therefore identical for all processes, so that the differences in properties and machinability were only due to process-related influences, in particular the type of energy input and the shape of the starting material. The selected particle dimensions and the used wire diameter were process-dependent; their determination originated from previous investigations [2,11].…”

Effect of stress-relief anneal time on residual stress of Co-Cr-Mo parts manufactured with selective laser melting

“…The residual stress induced as a result of the additive manufacturing process was simulated using the SAS package. SAS offers three calculation methods for simulating the SLM process: mechanical; thermal; and thermo-mechanical [16,[26][27][28]. These calculation methods can be used to determine the final shape of the component after residual stresses have caused deformation; detect hot spots and possible errors due to lack of fusion; examine the final microstructure; and digitally apply and test process parameters before manufacturing.…”