Turbine blade erosion is accelerated by high moisture content in steam.

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Erosion of turbine blades mainly comes from the impact of liquid droplets carried by steam. When the steam is wet, there are more liquid droplets present that strike the blade surfaces at high speed. Each droplet impact can remove material and create surface damage; with more moisture, there are more impacts and more energy in those impacts, so the erosion rate increases. So high moisture content in the steam accelerates erosion.

In comparison, very dry steam has fewer droplets and less energetic interactions, reducing erosion. High purity of steam affects corrosion and deposit-related issues more than the liquid-droplet erosion rate, and low velocity reduces the energy of each impact, further reducing erosion.