steel for turbin

Brief introduction

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.

Outline

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.

Ferritic stainless steel

Chromium 15% to 30%. Its corrosion resistance, toughness and weldability with the increase of chromium content increased resistance to chloride stress corrosion better than other types of stainless steel, fall into this category have Crl7, Cr17Mo2Ti, Cr25, Cr25Mo3Ti, Cr28 and so on.

Ferritic stainless steel because of high chromium content, corrosion and oxidation resistance are relatively good, but poor mechanical properties and process performance, and more for large discontinuity acid structure and antioxidant for steel. Such stainless steel is resistant to corrosive atmosphere, nitric acid and saline solution, and has good oxidation resistance, thermal expansion coefficient, etc., for the nitric acid plant equipment and food, can also be produced parts at high temperatures, such as gas turbine parts, etc. .

Car fender

Fender also called fenders, wheels are covered exterior body panels. Follow the installation location is divided into the front fender and rear fender.

The role of the automobile fender

Use of fluid, reducing the drag coefficient, allowing vehicles to pass more smoothly. Front fender mounted in the front office, because the front wheel steering function, it is necessary to ensure that the maximum limit of space front wheel rotation, so the designer can verify fender according to the size of the selected tire model with the “wheel hop map” plate design dimensions. Rear fender wheel rotation grazing without question, but aerodynamic considerations, slightly arched rear fender bulge outward arc.

Invention and the use of stainless steel

Invention and the use of stainless steel, dates back to the First World War. British scientist Henry Bray Hurley cloth by improving the work commissioned by the British government military arsenal, weapons research. At that time, the soldiers bore rifle with easy to wear, Bray Hurley wanted to invent a scratch-resistant alloy.
Stainless Bray Hurley invention patent made in the United Kingdom in 1916 and began mass production, so far, from the accidental discovery of stainless steel trash swept the world, Henry Bray Hurley is also known as the “father of stainless steel.” World War I, the British firearms on the battlefield, always wear unusable due to the chamber and transported back to the rear.

Military production department command the development of high strength wear-resistant alloy Bray Hurley, specializing in solving the problem of wear and chamber. Bray Hurley and his assistant collected domestic and foreign production of various types of steel products, various properties of steel, in a variety of different types of mechanical performance test, and then select a more suitable guns made of steel. One day, they experimented with a lot of chromium containing steel-made, after the wear-test to identify this alloy is not wearable, indicating that not manufacture guns, so they record the results, to fling a corner thing. One day, an assistant holding a piece of Zeng light watt light steel excitedly came a few months later to Bray Hurley said: “Sir, this is what I found when cleaning warehouse Mr. Mao La alloy sent you Whether the experiment to see if it has any special role in the end! “” Good! “Bray Hurley looked glittering steel, said happily.

Experimental results show that: it is a afraid of acid, alkali, salt stainless steel. This stainless steel is a German invention of the mullahs in 1912, however, the mullahs did not know what purpose this stainless steel.

Bray Hurley thought to myself: “The? This does not wear it corrosion-resistant steel, guns can not be produced, whether it can do dishes,” he went ahead and hands-on production of stainless steel fruit knife, fork, spoon, fruit plate and folding knives.