FOERSTER
Application notes
High-Temperature Corrosion on Turbine Blades

Detection of High-Temperature Corrosion on Turbine Blades

High-temperature corrosion on turbine blades can weaken the material unnoticed and compromise operational safety. Permeability measurement with MAGNETOSCOP detects even small areas of sulfidation and supports reliable condition assessment.

The challenge

Turbine blades used in aircraft engines and energy applications are exposed to extremely high temperatures and demanding operating conditions. Although nickel-based alloys are specifically designed to withstand these environments, prolonged thermal exposure can lead to high-temperature corrosion known as sulfidation.

At temperatures of approximately 700 °C and above, sulfur-containing compounds can react with the blade material and progressively attack the alloy. Even small affected areas can weaken the material and increase the risk of crack formation and, ultimately, component failure.

A particular challenge is that early-stage sulfidation is not necessarily visible on the surface. Reliable maintenance therefore requires a sensitive method capable of detecting material changes before significant damage becomes apparent.

The solution

Sulfidation changes the magnetic properties of the affected material. While the nickel-based alloy of an intact turbine blade is essentially non-ferromagnetic, corrosion can create locally ferromagnetic areas. These changes can be detected by measuring the magnetic permeability of the material.

FOERSTER uses highly sensitive permeability probes to identify these localized changes. As the extent of the affected material increases, the measured permeability signal also increases, providing an indication of the condition of the turbine blade.

For manual inspection during maintenance, the portable MAGNETOSCOP 1.070 can be used together with the suitable permeability probe P-P-2-5. The probe is guided across the relevant areas of the blade, enabling localized magnetic changes associated with sulfidation to be detected.

For automated inspection processes, the MAGNETOMAT 1.790 provides an alternative solution. Up to four measuring probes can be operated in parallel, allowing larger areas or multiple inspection positions to be evaluated efficiently within an automated setup.

The result

Magnetic permeability measurement makes it possible to detect even small areas affected by sulfidation that may not yet be visually apparent. This provides maintenance personnel with an additional means of assessing the condition of turbine blades and identifying critical material changes at an early stage.

The measurement is non-destructive and can be performed manually or integrated into automated inspection processes. Depending on the application, the MAGNETOSCOP enables flexible localized measurements during maintenance, while the MAGNETOMAT supports higher inspection throughput through parallel operation of multiple probes.

By making otherwise hidden magnetic changes measurable, the method supports reliable condition assessment and helps identify high-temperature corrosion before it can progress to more severe component damage.