Comparison of low cycle fatigue behaviour of additively manufactured and wrought Inconel625 alloys

Abstract

The present investigation highlights a comparison of strain-controlled low cycle fatigue (LCF) behaviour between the additively manufactured (AM) and wrought (WR) Inconel625 alloys at the total strain amplitude levels of +/- 0.4, +/- 0.5, +/- 0.6 and +/- 0.8 % at 650 degrees C. The cyclic life has been found to be lower in the AM alloy as compared to the WR alloy. The evolution of precipitates such NbC and gamma '' are found in both type of alloys after LCF tests. However, the AM alloy has shown a significant presence of (Cr,Mo)23C6 along the grain boundaries, which acts as a potential source of generation of the intergranular cracks during cyclic deformation. Although, a relatively fine grain structure and enhanced number density of high-angle boundaries have been identified in the LCF-tested samples of AM alloy through EBSD analyses, the formation of intergranular cracks in the AM alloy has resulted in the reduction of cyclic life of the AM alloy.