Change in turbine blade turbine blade steel movement in general. Role of the high temperature high pressure steam turbine blade, the work bear greater moment, high-speed operation of the rotor blade but also to withstand a high centrifugal force; Yan in wet vapor region of the blade, in particular the last stage, is subjected to electrochemical erosion corrosion and water droplets. rotor blades also bear very complex excitation force. Thus, blade steel should meet the following requirements:
① there is enough room, high temperature mechanical properties and resistance to change performance Shan,
② have high resistance to vibration attenuation;
③ high organizational stability;
④ good resistance to corrosion and erosion capability;
⑤ good process performance.
Blade material application ICrl3, ZCrz3, etc., and as a major group containing Mo, W, Nb, B, Ni 12% strengthening elements such as a 13% Cr steel, good vibration resistance and corrosion resistance, becoming the turbine blades material ‘but in some leaf cluster operating temperature of 400 ℃ and work requirements are not high corrosion resistance superheated steam Yan district, some low-alloy steel blades are available in order to reduce costs, such as ZoerMo, ZsMnZv and 15MnMoVCu so on. Leaves in the wet steam region work required high corrosion resistance of stainless steel, and with the use of temperature increase and increased leaf size blade steel material to be used has a higher temperature strength or intensity. Icr13,2Cr13 the like can be used for operating temperatures cluster 45. ‘C leaves. Temperature exceeds 500 ℃, need to ICr13 based on the type, multi-alloy elements added Mo, W, Nb, B, Ni, etc. to strengthen the steel.
CrllMoV steel for the working temperature as high temperature zone blade cluster of 540 ℃; CrlZWNIMoV working temperature (580C temperature zone blade, CrlZWMoNbVB steel blades for high-temperature region below 590C ZCrlZNIMo1WIV (US Steel No. C-422) for the large. capacity turbine rotor blades, the room temperature yield strength) 760 MPa large capacity units last stage blades centrifugal force due to its large size and thus suffered large, the use of alloying elements have a high yield strength of reinforcing steel 12% Cr: If height is 851 mm blade with ZCrllNIMo1V steel (plant grade), yield strength of not less than 655 MPa; blade height of about 1000 mm, using ZCrlZNiZWIMolV, the yield strength of not less than 735 MPa. Further, still with reduced tempering temperature, at the expense of a small amount of ductility and toughness, a method to obtain high strength. More advanced approach is to use a small proportion of high-strength materials, such as titanium alloy materials, etc., and TIA16V4 and TIA17Mo4 carbide or glass fiber reinforced plastics are being used in research as the final stage of a long blade material, which accounts for only a quarter of steel one. Leaf surface strengthening protection last stage blades and the second last stage blades, especially in the upper inlet vane dorsal arc Department has serious water erosion damage problem, the solution is to strengthen the protection of surface treatment, such as silver solder Stellite piece surface hardening, EDM strengthen, chrome, plasma spraying, nitriding. Among Stellite piece best resistance to water erosion.