The low cycle fatigue property, damage mechanism, and life prediction of additively manufactured Inconel 625: Influence of temperature

Abstract

Symmetrical high‐temperature low‐cycle fatigue tests were performed in this study to examine the influence of temperature on the fatigue failure mechanism of the additively manufactured Inconel 625. According to the fracture analysis, cracks initiate from the crystallographic plane at room temperature. At 600°C, oxidation of carbides leads to crack initiation. The strengthening effect of γ″ precipitation prevents crack propagating within the matrix. At 750°C, the crack becomes transgranular propagating, as a consequence of γ″‐δ transformation. Geometrically necessary dislocations distribution on the fracture supports this result. Furthermore, a modified life prediction formula considering effect of temperature and strain amplitude was established. It was observed that the modified model predicted the fatigue life of the studied materials well in both test conditions.

Analysis of Environmental Impact and Mechanical Properties of Inconel 625 Produced Using Wire Arc Additive Manufacturing

“…Fatigue testing was performed on 15 samples at a range of maximum stresses between 100% and 160% of the yield strength of the material with the results plotted in Figure 12. These results show that the material begins to experience run-out at 100% of yield, remaining in the high cycle regime at 160% of yield; hence, it exceeds the previously published performance of wrought and welded material [28,29,47], while closely matching the results found for material produced through PM and HIP [27].…”

“…Furthermore, the st was found to be comparable to previous studies of this combination of material an cess [25,46], while the elongation was found to be superior due to a reduced develo of the δ phase. This enhanced elongation was found to be beneficial to the fatigue p mance of the alloy, which was superior to the wrought alloy and comparable to oth methods [28,29,47].…”

“…An additional factor which is important for engineering components is their response to cyclic loading which has been identified as a challenge for rotating systems since 1858 [26]. The fatigue performance of Inconel 625 has previously been assessed for material produced through a range of processes, including powder metallurgy (PM-HIP) [27], laser powder bed fusion (LPBF) [28], and welded plates [29]. The results presented in this study for WAAM-produced material will be compared with the previously published literature to determine its suitability for use in industry as a replacement for existing processes.…”