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

Adnan U Syed,Martin Frommherz,John R Nicholls,Tracey Roberts,Simon Gray,Fabian Duarte Martinez,Adriana Encinas-Oropesa,Nicolau I Morar,Marlene Grohne

doi:10.1007/s11085-021-10044-9

Adnan U Syed, Martin Frommherz + Show 7 more

Open Access

https://doi.org/10.1007/s11085-021-10044-9

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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.

Highlights

Hot corrosion (HC) is an aggressive mode of attack typically experienced in the under-platform region of aero-gas turbine blades
The study of cyclic HC testing in addition to isothermal testing is important for a better simulation of jet engine turbine components performance
This paper reports the results of hot corrosion isothermal exposures carried out at 700 and 900 °C and thermal cyclic SC and LC tests using the well-established deposit recoat test method

Summary

Introduction

Hot corrosion (HC) is an aggressive mode of attack typically experienced in the under-platform region of aero-gas turbine blades. It results from the reaction of the fuel with contaminants in the air inlet, which leads to the formation of molten deposits, typically N a2SO4 [1]. Whether spallation occurs depends on a complex interplay of conditions, such as the maximum operating temperature, the test environment, accumulated time at maximum temperature and heating/cooling rates. For this reason, accounting for these events is of utmost importance to understand the mechanism that underlies the corrosion resistance of nickel-based superalloys. The current study uses both isothermal and cyclic HC tests to gain an understanding of hightemperature degradation behaviour and influence of alloying additions

Experimental Procedures

Results and Discussion

49 PWA1484

Conclusions