Influence of substrate characteristics on residual stress of SLMed Inconel 718

Abstract

Purpose

Selective laser melting (SLM) is a promising additive manufacturing technology in the field of complex parts’ fabrication. High temperature gradient and residual stress are vital problems for the development of SLM technology. The purpose of this paper is to investigate the influence of substrate characteristics on the residual stress of SLMed Inconel 718 (IN718).

Design/methodology/approach

The SLMed IN718 samples were fabricated on the substrates with different characteristics, including pre-compression stress, materials and pre-heating. The residual stress at the center of the top surface was measured and compared through Vickers micro-indentation.

Findings

The results indicate that the residual stress reduces when the substrate contains pre-compression stress before the SLM process starts. Both substrate thermal expansion coefficient and thermal conductivity affect the residual stress. In addition to reducing the difference of thermal expansion coefficient between the substrate and the deposited material, the substrate with low thermal conductivity can also decrease the residual stress. Substrate pre-heating at 150°C reduces nearly 42.6 per cent residual stress because of the reduction of the temperature gradient.

Originality/value

The influence of substrate characteristics on the residual stress has been studied. The investigation results can help to control the residual stress generated in SLM processing.

Citation

Cheng, Y., Xiao, Z., Zhu, H., Zeng, X. and Wang, G. (2019), "Influence of substrate characteristics on residual stress of SLMed Inconel 718", Rapid Prototyping Journal, Vol. 25 No. 4, pp. 792-799. https://doi.org/10.1108/RPJ-09-2018-0238