Which of the following is a cold-section repair method for an axial flow compressor?

• A. Blending
• B. Plasma surface repair coating
• C. Blade replacement
• D. Electron beam welding

Answer: (A)

Cold-section repairs are done at ambient temperature to restore surface shape without heating the part. Blending mechanically removes a small amount of material to smooth out nicks, corrosion, or roughness, returning the blade or casing to its proper profile without altering the metal’s microstructure. This preserves the original material properties and avoids any heat-affected zones, which is essential for components in the cold section of an axial flow compressor. The other options involve heat input or replacement rather than purely restoring the surface: a thermal spray coating adds material using high heat, electron beam welding relies on a high-energy heat process to join metal, and blade replacement is a changeout rather than a surface restoration. So blending is the cold-section repair method.