Tungsten in the Steam Turbine Blades

A turbine blade is the essential part in a steam turbine. Turbine blades are subjected to high temperature and high pressure steam, and they are subjected to large bending moments during operation. The moving blades in high speed operation are also subjected to high centrifugal force; the blades in the wet stream areaare subject to electrochemical Corrosion and water droplets impinge on moving blades are also subject to very complex exciting forces. Therefore, the steel for blade should meet the following requirements: high temperature mechanical properties and anti-creep property; high resistance to vibration damping; high structural stability; good corrosion and erosion resistance.

The reason why the blades become the main consumable parts of the steam turbines is, the vibration resistance and corrosion resistance of the conventional steam turbine blades are not high enough.

In order to overcome the shortcomings of traditional steam turbine blades, it is necessary to add Mo, W, Nb, B, Ni, to strength the steel, which has good vibration resistance and corrosion resistance. Finally, it is made into high-hardness and corrosion-resistant steam turbine blades.

The high-hardness reinforced steel steam turbine blade is made up of 16% inorganic metal silicon as the base, consisting of a protective coating, a structural blade and a heat conducting unit. The physical properties of the metal silicon semi-conductive are used to remove half of the heat loss, supplemented by 16%. High hardness yields metal tungsten and 35% corrosion-resistant metal chromium based, plus 5% Mo, 3% Nb, 2% B, 2% Ni and other strengthening elements.

The role of 16% metal tungsten is to strengthen the yield strength and hardness of the material. The melting point of metal tungsten is 3410±20°C, the boiling point is 5927°C, the Mohs hardness is 7.5, the torsional modulus is more than 36000Mpa, but the plasticity and toughness are reduced, and the chromium can be improved. Steel's oxidation resistance and corrosion resistance. Chromium is a polyvalent metal element with an atomic number of 24 and is usually made of chromium. It is hard and brittle, but its role is to strengthen its anti-oxidized ability and stabilized by corrosion. The service life of the material is specially designed for some steam turbines with high requirements on blade strength. The combination of metal tungsten and chromium can improve the material strength and corrosion resistance on the one hand, and strengthen the strength coefficient of these two points on the other hand.

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