Influence of dwell time on fatigue crack propagation in Alloy 718 laser welds
Journal article, 2017

The introduction of welded assemblies in aerospace components aid in weight reduction, but also lead to an increased risk of defects. It is therefore important to analyze the high temperature crack growth resistance of such welds. The results from high temperature cyclic and dwell-fatigue testing of surface flawed Alloy 718 welds are presented here. An increasing temperature and application of a dwell time accelerate the crack growth and increase interaction with secondary phases. During cyclic loading at 550 °C, there is little interaction with the microstructure during transgranular propagation, but the application of dwell times results in a mixture of transgranular propagation and intergranular cracking of boundaries between different dendrites. At 650 °C, mixed intergranular and transgranular mode of crack growth is seen under both cyclic and dwell conditions. However, during dwell-fatigue the interfaces between the secondary arms of the same dendrite are also weakened, leading to an interfacial type of crack growth also in the intergranular parts.

Nickel superalloys


Crack growth

Laser welds

Electron microscopy



Anand Harihara Subramonia Iyer

Chalmers, Physics, Materials Microstructure

Krystyna Marta Stiller

Chalmers, Physics, Biological Physics

Chalmers, Physics, Materials Microstructure

Gunnar Leijon


Henrik C.M. Andersson-Östling


Magnus Hörnqvist Colliander

Chalmers, Physics, Materials Microstructure

Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

0921-5093 (ISSN)

Vol. 704 440-447

Subject Categories

Metallurgy and Metallic Materials


Chalmers Materials Analysis Laboratory

Areas of Advance

Materials Science



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