Effect of melt parameters on density and surface roughness in electron beam melting of gamma titanium aluminide alloy

Author(s):

Ashfaq Mohammad , (Princess Fatima Alnijiris’s Research Chair for Advanced Manufacturing Technology (FARCAMT Chair), Advanced Manufacturing Institute, King Saud University, Riyadh, Saudi Arabia)

Abdurahman Mushabab Al-Ahmari , (Princess Fatima Alnijiris’s Research Chair for Advanced Manufacturing Technology (FARCAMT Chair), Advanced Manufacturing Institute, King Saud University, Riyadh, Saudi Arabia)

Abdullah AlFaify , (Department of Industrial Engineering, King Saud University, Riyadh, Saudi Arabia)

Muneer Khan Mohammed , (Princess Fatima Alnijiris’s Research Chair for Advanced Manufacturing Technology (FARCAMT Chair), Advanced Manufacturing Institute, King Saud University, Riyadh, Saudi Arabia)

Citation:

Ashfaq Mohammad, Abdurahman Mushabab Al-Ahmari, Abdullah AlFaify, Muneer Khan Mohammed, (2017) "Effect of melt parameters on density and surface roughness in electron beam melting of gamma titanium aluminide alloy", Rapid Prototyping Journal, Vol. 23 Issue: 3, pp.474-485, https://doi.org/10.1108/RPJ-12-2014-0187

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Abstract:

Purpose

Electron beam melting (EBM) is one of the potential additive manufacturing technologies to fabricate aero-engine components from gamma titanium aluminide (γ-TiAl) alloys. When a new material system has to be taken in to the fold of EBM, which is a highly complex process, it is essential to understand the effect of process parameters on the final quality of parts. This paper aims to understand the effect of melting parameters on top surface quality and density of EBM manufactured parts. This investigation would accelerate EBM process development for newer alloys.

Design/methodology/approach

Central composite design approach was used to design the experiments. In total, 50 specimens were built in EBM with different melt theme settings. The parameters varied were surface temperature, beam current, beam focus offset, line offset and beam speed. Density and surface roughness were selected as responses in the qualifying step of the parts. After identifying the parameters which were statistically significant, possible reasons were analyzed from the perspective of the EBM process.

Findings

The internal porosity and surface roughness were correlated to the process settings. Important ones among the parameters are beam focus offset, line offset and beam speed. By jointly deciding the total amount of energy input for each layer, these three parameters played a critical role in internal flaw generation and surface evolution.

Research limitations/implications

The range selected for each parameter is applicable, in particular, to γ-TiAl alloy. For any other alloy, the settings range has to be suitably adapted depending on physical properties such as melting point, thermal conductivity and thermal expansion co-efficient.

Practical implications

This paper demonstrates how melt theme parameters have to be understood in the EBM process. By adopting a similar strategy, an optimum window of settings that give best consolidation of powder and better surface characteristics can be identified whenever a new material is being investigated for EBM. This work gives researchers insights into EBM process and speeds up EBM adoption by aerospace industry to produce critical engine parts from γ-TiAl alloy.

Originality/value

This work is one of the first attempts to systematically carry out a number of experiments and to evaluate the effect of melt parameters for producing γ-TiAl parts by the EBM process. Its conclusions would be of value to additive manufacturing researchers working on γ-TiAl by EBM process.

Keywords:

Additive manufacturing, Electron beam melting, Density, Surface roughness, Energy input, Titanium aluminide

Type:

Research Paper

Publisher:

Emerald Publishing Limited

Received:

30 December 2014

Revised:

08 March 2015, 13 June 2016

Accepted:

15 June 2016

Acknowledgments:

This project was funded by the National Plan for Science, Technology and Innovation (MAARIFAH), King Abdul-Aziz City for Science and Technology, Kingdom of Saudi Arabia, Award Number (11-ADV1494-02).

Copyright:

© Emerald Publishing Limited 2017
Published by Emerald Publishing Limited
Licensed re-use rights only