Abstract
Additive Layer Manufacturing (ALM) is becoming a more widely accepted method for the production of near net-shape products across a range of industries and alloys. Depending on the end application, a level of process substantiation is required for new parts or alloys. Prior knowledge of the likely process parameter ranges that will provide a target region for the process integrity can save valuable time and resource during initial ALM trials. In this paper, the parameters used during the powder bed ALM process have been taken from the literature and the present study to construct normalised process maps for the ALM process by building on an approach taken by Ion et al. in the early 1990's (J.C. Ion, H.R. Shercliff, M.F. Ashby, Acta Metallurgica et Materialia 40 (1992) 1539–1551). These process maps present isopleths of normalised equivalent energy density (E0*) and are designed to provide a practical framework for comparing a range of ALM platforms, alloys and process parameters and provide a priori information on microstructure. The diagrams provide a useful reference and methodology to aid in the selection of appropriate processing parameters during the early development stages. This paper also applies the methodology to worked examples of Ti–6Al–4V depositions processed using different Electron Beam Melting parameters.
Highlights
IntroductionAdditive Layer Manufacture (ALM) is an emerging near-net shape production technology that utilises a high-energy heat source (typically a laser or high-energy electron beam) to selectively melt or fuse together metallic powder to produce a three dimensional part direct from a CAD model on a layer by layer basis [1]
Additive Layer Manufacture (ALM) is an emerging near-net shape production technology that utilises a high-energy heat source to selectively melt or fuse together metallic powder to produce a three dimensional part direct from a CAD model on a layer by layer basis [1]
In the range 3 < E0* < 5 (Fig. 4 c to j), rapid cooling through the b / a þ b transformation temperature results in a fine, Widmansta€tten a morphology and this is consistent with the microstructures reported for ALM Tie6Ale4V
Summary
Additive Layer Manufacture (ALM) is an emerging near-net shape production technology that utilises a high-energy heat source (typically a laser or high-energy electron beam) to selectively melt or fuse together metallic powder to produce a three dimensional part direct from a CAD model on a layer by layer basis [1]. Powder ALM can be broadly divided into two forms; Blown Powder Direct Laser Deposition and Powder Bed Additive Manufacture [2]. In both cases, the powder is locally fused together using a moving heat source, the delivery system for the powder differs. Insufficient heatinput due to high laser beam velocities is reported to introduce a high fraction of internal voids in CM247 LC by Carter et al [2,6] and in 316L Stainless Steel by Kamath et al [17], whilst Juechter et al [8] were able to define an acceptable processing parameter window for Electron Beam Manufacture (EBM) of Tie6Ale4V
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