Effect of alloy composition and laser powder bed fusion parameters on the defect formation and mechanical properties of Inconel 625

The Inconel 625 (IN625) superalloy has a high strength, excellent fatigue, and creep resistance under high-temperature and high-pressure conditions, and is one of the critical materials used for manufacturing high-temperature bearing parts of aeroengines. However, the poor workability of IN625 alloy prevents IN625 superalloy to be used in wider applications, especially in applications requiring high geometrical complexity. Laser powder bed fusion (LPBF) is a powerful additive manufacturing process which can produce metal parts with high geometrical complexity and freedom. This paper reviews the studies that have been done on LPBF of IN625 focusing on the microstructure, mechanical properties, the development of residual stresses, and the mechanism of defect formation. Mechanical properties such as microhardness, tensile properties, and fatigue properties reported by different researchers are systematically summarized and analyzed. Finally, the remaining issues and suggestions on future research on LPBF of IN625 alloy parts are put forward.

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Multi-Laser Powder Bed Fusion Benchmarking—Initial Trials with Inconel 625

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-019-04417-3 ◽

2019 ◽

Vol 105 (7-8) ◽

pp. 2891-2906 ◽

Cited By ~ 6

Author(s):

H. Wong ◽

K. Dawson ◽

G. A. Ravi ◽

L. Howlett ◽

R. O. Jones ◽

...

Keyword(s):

Mechanical Properties ◽

Heat Treatment ◽

Production Rate ◽

Single Mode ◽

Inconel 625 ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Single Laser ◽

Stress Relieving

Abstract Production rate is an increasingly important factor in the deployment of metal additive manufacturing (AM) throughout industry. To address the perceived low production rate of metal AM systems based on single-laser powder bed fusion (L-PBF), several companies now offer systems in which melting has been parallelised by the introduction of multiple, independently controlled laser beams. Nevertheless, a full set of studies is yet to be conducted to benchmark the efficiency of multi-laser systems and, at the same time, to verify if the mechanical properties of components are compromised due to the increase in build rate. This study addresses the described technology gaps and presents a 4-beam L-PBF system operating in “single multi” (SM) mode (SM-L-PBF) where each of the four lasers is controlled so that it melts all of a particular components’ layers and produces specimens for comparison with standard L-PBF specimens from the same machine. That is all four lasers making all of some of the parts were compared to a single-laser manufacturing all of the parts. Build parameters were kept constant throughout the manufacturing process and the material used was Inconel 625 (IN625). Stress-relieving heat treatment was conducted on As-built (AB) specimens. Both AB and heat-treated (HT) specimen sets were tested for density, microstructure, tensile strength and hardness. Results indicate that the stress-relieving heat treatment increases specimen ductility without compromising other mechanical properties. SM-L-PBF has achieved a build rate of 14 cm3/h when four 200 W lasers were used to process IN625 at a layer thickness of 30 μm. An increase in the build rate of 2.74 times (build time reduction: 63%) has been demonstrated when compared to that of L-PBF, with little to no compromises in specimen mechanical properties. The observed tensile properties exceed the American Society for Testing Materials (ASTM) requirements for IN625 (by a margin of 22 to 26% in the 0.2% offset yield strength). Average specimen hardness and grain size are in the same order as that reported in literatures. The study has demonstrated that a multi-laser AM system opens up opportunities to tackle the impasse of low build rate in L-PBF in an industrial setting and that at least when operating in single mode there is no detectable degradation in the mechanical and crystallographic characteristics of the components produced.

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Co–Cr–Mo alloy fabricated by laser powder bed fusion process: grain structure, defect formation, and mechanical properties

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-021-07570-w ◽

2021 ◽

Author(s):

Alex Matos da Silva Costa ◽

João Pedro Oliveira ◽

André Luiz Jardini Munhoz ◽

Eduardo Guimarães Barbosa Leite ◽

Denise Souza de Freitas ◽

...

Keyword(s):

Mechanical Properties ◽

Defect Formation ◽

Fusion Process ◽

Grain Structure ◽

Structure Defect ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed

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In Situ Alloying of a Modified Inconel 625 via Laser Powder Bed Fusion: Microstructure and Mechanical Properties

Metals ◽

10.3390/met11060988 ◽

2021 ◽

Vol 11 (6) ◽

pp. 988

Author(s):

Giulio Marchese ◽

Margherita Beretta ◽

Alberta Aversa ◽

Sara Biamino

Keyword(s):

Mechanical Properties ◽

Base Alloy ◽

Heat Treatments ◽

Inconel 625 ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Powder Bed ◽

Melt Pool ◽

Composition Modification

This study investigates the in situ alloying of a Ni-based superalloy processed by means of laser powder bed fusion (LPBF). For this purpose, Inconel 625 powder is mixed with 1 wt.% of Ti6Al4V powder. The modified alloy is characterized by densification levels similar to the base alloy, with relative density superior to 99.8%. The material exhibits Ti-rich segregations along the melt pool contours. Moreover, Ti tends to be entrapped in the interdendritic areas during solidification in the as-built state. After heat treatments, the modified Inconel 625 version presents greater hardness and tensile strengths than the base alloy in the same heat-treated conditions. For the solution annealed state, this is mainly attributed to the elimination of the segregations into the interdendritic structures, thus triggering solute strengthening. Finally, for the aged state, the further increment of mechanical properties can be attributed to a more intense formation of phases than the base alloy, due to elevated precipitation strengthening ability under heat treatments. It is interesting to note how slight chemical composition modification can directly develop new alloys by the LPBF process.

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