On the microstructure of laser beam powder bed fusion alloy 718 and its influence on the low cycle fatigue behaviour
Journal article, 2020

Additive manufacturing of Alloy 718 has become a popular subject of research in recent years. Understanding the process-microstructure-property relationship of additively manufactured Alloy 718 is crucial for maturing the technology to manufacture critical components. Fatigue behaviour is a key mechanical property that is required in applications such as gas turbines. Therefore, in the present work, low cycle fatigue behaviour of Alloy 718 manufactured by laser beam powder bed fusion process has been investigated. The material was tested in as-built condition as well as after two different thermal post-treatments. Three orientations with respect to the building direction were tested to evaluate the anisotropy. Testing was performed at room temperature under controlled amplitudes of strain. It was found that defects, inclusions, strengthening precipitates, and Young’s modulus influence the fatigue behaviour under strain-controlled conditions. The strengthening precipitates affected the deformation mechanism as well as the cycle-dependent hardening/softening behaviour. The defects and the inclusions had a detrimental effect on fatigue life. The presence of Laves phase in LB-PBF Alloy 718 did not have a detrimental effect on fatigue life. Young’s modulus was anisotropic and it contributed to the anisotropy in strain-life relationship. Pseudo-elastic stress vs. fatigue life approach could be used to handle the modulus-induced anisotropy in the strain-life relationship.

Additive manufacturing

Powder bed fusion

Hot isostatic pressing




Arun Ramanathan Balachandramurthi

University West

Nitesh Raj Jaladurgam

Chalmers, Physics, Microstructure Physics

Chamara Kumara

University West

Thomas Hansson

GKN Aerospace Sweden

University West

JJ Moverare

University West

Linköping University

Johannes Gårdstam

Quintus Technologies AB

Robert Pederson

University West


1996-1944 (ISSN)

Vol. 13 22 1-21 5198

Subject Categories

Manufacturing, Surface and Joining Technology

Other Materials Engineering

Metallurgy and Metallic Materials





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