Performance Comparison Between Isothermal Hot Corrosion And In Situ Cyclic Hot Corrosion of Nickel-Based Superalloys

Abstract

Although a lot of work has been done to understand both major mechanisms of hot corrosion, namely type I (high-temperature hot corrosion) and type II (low temperature hot corrosion), there is very little information available on more representative cyclic performance in these regimes. This work addresses this by assessing the performance of isothermal (type I and type II) hot corrosion tests against combined (short and long) cyclic corrosion tests. Single-crystal alloy PWA 1484 and directionally solidified alloy MAR-M247 were assessed in all test regimes. Pre- and post-exposure dimensional metrology was used to quantify the corrosion damage and characterised using SEM/EDX. This paper highlights that the results of short cycle test conditions are more damaging compared to long cycle and standard isothermal type I and II test conditions. The cast nickel-based alloy MAR-M247 was found to be a better performer compared to PWA 1484 single-crystal alloy.

Crack Initiation in Ni-Based Single Crystal Superalloy under Low-Cycle Fatigue-Oxidation Conditions

“…The effect of temperature on crack initiation is mainly related to high-temperature oxidation. The formation of cracks in surface oxides that can split into different oxide layers is mainly due to the different thermal expansion coefficients between the oxide layer and the alloy matrix, which is prone to stress concentration and crack formation [13][14][15]. The higher the temperature, the faster the oxidation rate, the easier the crack initiation at the oxide layer [16,17].…”

Machine Learning Applied to Identify Corrosive Environmental Conditions

“…In reality, the specifics of the environment experienced by engines are not fully known, and the environmental impacts on jet engine turbine blades are still a matter of research (Darolia, 2019). To ascertain the response of blade materials to inflight conditions, researchers have recreated representative environments in laboratories in which metallic materials are sprayed with a thin layer of salt contaminants and exposed to high temperatures (Eliaz et al, 2002;Rapp, 2002;Syed et al, 2021). Samples are afterward inspected with microscopes and weighted to assess the superalloy resistance to corrosion damage.…”