Thermo-Mechanical Properties of SLM Processed Materials: 316l Stainless Steel, Aluminum and Titanium

Abstract: In this paper, the aim was to present the thermo-mechanical properties of 3D-printed alloys. In the rapidly advancing technological world, production techniques are also trying to get their place. Additive Manufacturing, a new production technique, is rapidly progressing on this path and gaining importance and place in this period. Layer based manufacturing technique (3D printing or Additive Manufacturing (AM)) has opened a new way of making simple and intricate components in the manufacturing industry. AM has different production techniques. Selective Laser Melting (SLM) is one of them. Selective Laser Melting (SLM) is a powder-based additive manufacturing capability to produce parts layer-by-layer from a 3D CAD model. The goal of selective laser manufacturing is to produce parts that have properties like or better than traditional methods The SLM technique has many production parameters, such as laser power and scanning speed. This study will be done on the previously mentioned parameters and the effect of these parameters on the coefficients of thermal expansion (CTE) on alloys will be investigated. As the most widely used materials in the industry are 316L Stainless Steel, Aluminum (AlSiMg10), and titanium (Ti6Al4V). These very popular materials are produced with the Selective Laser Melting technique and CTE values are compared. In this study, CTE values of alloys produced with SLM in different parameters will be examined. These parameters were determined as Laser power and Scanning speed and other parameters were kept constant. The laser power, which is one of the parameters of these samples, was determined as 50W, 75W, 100W while scanning speeds were determined as 0.2 m/s, 0.4 m/s, 0.6 m/s. By applying 9 different variations in these parameters, CTE values were compared by analyzing separate samples produced at different speeds and powers with a dilatometer. While applying these variations, the Taguchi method was applied. Production parameters-power and scanning speed were varied, and the thermal coefficient of expansions of the 3D-printed parts was characterized using the Netzsch’s Dilatometer 402 C. While doing this work, the sample to be produced was designed with SolidWorks. Each of the samples is in the form of a cylinder with a diameter of 6 mm and a length of 12mm.In addition to these studies, the samples produced with SLM were annealed and the change in CTE values was compared with non-annealed samples. Aluminum was heat-treated at 415 ⁰C and stainless steel at 700 ⁰C for 90 minutes. Titanium is annealed for 3 hours at 785 ⁰C. As a next step, the microstructure of the samples will be examined comparatively. The effect of annealing and production parameters will be examined in detail with the Scanning Electron Microscope (SEM).

Keywords: Additive manufacturing, 3D-printing, coefficient of thermal expansion, dilatometer, selective laser melting.