Multi-Perspective Analysis of Building Orientation Effects on Microstructure, Mechanical and Surface Properties of SLM Ti6Al4V with Specific Geometry.

Wentong Cai,Qinghua Song,Munish Kumar Gupta,Hansong Ji

doi:10.3390/ma14164392

Wentong Cai, Qinghua Song + Show 2 more

Open Access

https://doi.org/10.3390/ma14164392

Copy DOI

Abstract

Building orientation is important in selective laser melting (SLM) processes. Current studies only focus on the horizontal and vertical building orientations without considering different modes of horizontal orientations. In fact, for horizontal orientation, different surfaces of the sample that contact the substrate will affect the heat transfer mode and efficiency, and in turn affect the microstructure and material properties. In this paper, the effect of two modes of horizontal building orientations on microstructure, mechanical and surface properties of SLM Ti6Al4V was studied. Current research about building orientation is deficient because the geometry of samples or test surfaces are not strictly defined, which seriously influences the results due to their different heat transfer efficiency and mode. Therefore, the geometry of the samples and test surfaces were clearly defined, and its necessity was proved in this study. To achieve the research goal, three test samples were prepared: sample SLM-PB-S with the building orientation parallel to the substrate and the shorter side L1 contacts it, sample SLM-PB-L with the building orientation parallel to the substrate and the longer side L2 contacts it and sample SLM-VB with the building orientation vertical to the substrate. Subsequently, the microstructure, grain information, densification, residual stress, micro-hardness, tensile properties and surface topography of different samples were analyzed and compared. In the results, SLM-PB-S exhibited denser microstructure and better mechanical properties than SLM-PB-L, including smaller grain size, stronger texture, higher density, micro-hardness, tensile strength, plasticity and better surface quality. It originates from a higher cooling rate and shorter scanning time between layers during SLM-PB-S fabrication, leading to finer grains, lower porosity and better interlayer metallurgical bonding, thus resulting in better material properties. This study can provide a reference to select the proper building orientation in SLM.

Highlights

This paper aims to solve the three problems: different geometries for samples affect the Thisresults, paper which aims to the three problems: different forare samples affect research is solve not recommended; previous researchgeometries perspectives incomplete; the research which is not recommended; previoushas research perspectives are inand the effectresults, of different horizontal building orientations rarely been studied before
Ti6Al4V is a typical alloy with dual phase (α + β), and its performance is closely related to the microstructural morphology [5]
The initial microstructure of Ti6Al4V titanium alloy mainly depends on the cooling rate during the forming process

Summary

Introduction

Ti6Al4V is a typical α + β type titanium alloy [1]. It has the characteristics of high specific strength, good corrosion resistance, excellent biocompatibility and sound comprehensive mechanical properties. It has been widely used in aerospace, ship and medical equipment and other fields [2,3,4]. Additive manufacturing (AM) technology encompasses multiple disciplines of physics, machinery, materials, etc. Compared with milling, turning, grinding and other traditional subtractive manufacturing technologies, additive manufacturing has a great advantage in rapid prototyping, independent design and accessibility of complex parts [5,6]. The study on AM materials has aroused the interest of many researchers who try to improve the properties of the materials

Objectives

Methods

Results

Conclusion