Fatigue and crack growth behavior of Inconel 718–AL6XN dissimilar welds

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 745; pp. 20 - 30
• Main Authors: Cortés, R., Rodríguez, N.K., Ambriz, R.R., López, V.H., Ruiz, A., Jaramillo, D.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 04.02.2019; Elsevier BV
• Subjects: Austenitic stainless steels; Crack propagation; Diamond pyramid hardness; Dissimilar material joining; Fatigue crack growth; Fatigue failure; Fatigue tests; Fracture mechanics; Fracture surfaces; Gas tungsten arc welding; GTAW; Heat affected zone; Heat treating; High cycle fatigue; Inconel-AL6XN; Nickel base alloys; Niobium carbide; Striations; Superalloys; Weld metal; Welded joints; Wöhler curves; Fatigue crack growth; GTAW; Inconel-AL6XN; Wöhler curves
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2018.12.087

The fatigue and crack growth behavior of Inconel 718 and AL6XN alloys joined with an ERNiFeCr-2 filler by the gas tungsten arc welding process was evaluated. A comparison between Wöhler curves for the monolithic IN718 and AL6XN alloys and the IN718-AL6XN dissimilar welded joint were obtained. Although Vickers microhardness profiles revealed the presence of a soft region in the heat affected zone of the IN718 base material, the fatigue crack nucleated at the fusion zone near to the AL6XN and propagated across the weld bead. The welded joint and the AL6XN base material presented a similar high cycle fatigue behavior despite the presence of an unmixed zone at the AL6XN/weld metal interface. The results of the fatigue crack growth test indicated that the weld metal has the highest growing rate owing to the presence of brittle secondary phases such as Laves and NbC. The fatigue crack growth rates obtained from experimental data were compared with measurements of the distance between striations on the fracture surfaces, both were very close.