The Influence of Iron in Minimizing the Microstructural Anisotropy of Ti-6Al-4V Produced by Laser Powder-Bed Fusion

Abstract

There remains a significant challenge in adapting alloys for metal-based additive manufacturing (AM). Adjusting alloy composition to suit the process, particularly under regimes close to industrial practice, is therefore a potential solution. With the aim of designing new Ti-based alloys of superior mechanical properties for use in laser powder-bed fusion, this research investigates the influence of Fe on the microstructural development of Ti-6Al-4V. The operating mechanisms that govern the relationship between the alloy composition (and Fe in particular) and the grain size are explored using EBSD, TEM, and in situ high-energy synchrotron X-ray diffraction. It was found that Fe additions up to 3 wt pct lead to a progressive refinement of the microstructure. By exploiting the cooling rates of AM and suitable amount of Fe additions, it was possible to obtain microstructures that can be optimized by heat treatment without obvious precipitation of detrimental brittle phases. The resulting microstructure consists of a desirable and well-studied fully laminar a + b structure in refined prior-b grains.

Compression Property, Deformation Behavior, and Fracture Mechanism of Additive-Manufactured Ti-6Al-4V Cellular Solid with a New Cuboctahedron Structure

“…[5] The length and width of the columnar grains are~1000 and~100 lm, respectively. [4,5,9,11] Figure 3(a) indicates that the microstructure of the SLM specimen was also acicular a¢-martensite dispersed within columnar grains, which was consistent with the literature. [14,16,26,27] The decomposition of a¢ martensite during the cooling stage of the SLM process was not observed in this study.…”

“…In SLM solid Ti-6Al-4V alloy, the microstructure is generally acicular a¢-martensite dispersed within columnar grains. [4][5][6]9,11] This kind of microstructure arises from prior b columnar grains and a cooling rate as high as 1000°C/s during SLM. [5] The length and width of the columnar grains are~1000 and~100 lm, respectively.…”

“…Powder bed fusion (PBF) with a laser beam or electron beam as the heating source is the dominant technique for AM metallic materials. [4][5][6][7][8][9] Among the AM metallic materials, Ti-based alloys, particularly Ti-6Al-4V, are promising materials for various applications and have been widely produced and studied. [8][9][10][11][12][13][14][15][16][17][18] The mechanical properties and fracture behaviors of AM cellular Ti-6Al-4V are dominantly controlled by the type of lattice and the porosity.…”

Manufacturing of Closed Impeller for Mechanically Pump Fluid Loop Systems Using Selective Laser Melting Additive Manufacturing Technology

“…In this context, several studies were conducted for a deeper understanding control of the effects that currently limit the fidelity of LPBF as a microstructure, residual stress, micro-roughness and porosity of AM materials. Simonelli et al [16] investigated the influence of Fe on the microstructural development of Ti-6Al-4V used for LPBF, and Gussone et al [17] demonstrated the feasibility of Ti-Fe alloys used for LPBF with ultrafine microstructures and mechanical strength for structural application. In [18] and [19], the authors provide a brief overview of alloy design strategies, highlighting the potential for alloys to match to the unique processing conditions encountered during the AM process.…”

Densification, Microstructure, and Mechanical Properties of Additively Manufactured 2124 Al–Cu Alloy by Selective Laser Melting

“…Due to the great demand for AM parts made from Al alloys, SLM processing of Al alloys such as Al-Si [3,4], Al-Zn [5], Al-Cu [6,7], Al-Sc [8], and Al-Mg-Sc-Zr [9] have been studied systematically. The concept of adjusting material composition to fit the AM process was proposed to meet more application requirements [10,11]. However, due to the inherently high laser reflectivity and high thermal conductivity of Al alloy powders, it is generally difficult to produce Al alloy parts with a high performance by SLM.…”