In the process of production of heat-resistant castings mainly refers to working under high temperature steel, heat-resistant castings in the development process and the gas turbine power plant and boiler, internal combustion engine, engine technology progress in aviation and other industries are closely related, in the use of various types of machinery and equipment due to the use of temperature and stress under different therefore, the types of steel are also different.
A heat-resisting casting high temperature oxidation resistance and high strength steel. High temperature oxidation resistance is an important condition to ensure the work long workpieces at high temperature. The steel in high temperature air oxidation environment, oxygen and chemical reaction of various iron oxide layer steel surface, the oxide layer is very loose, easy to fall off to. High temperature oxidation resistance of steel is improved, adding to the alloy elements in the steel, thereby changing the structure of the oxide.
The alloy elements in the process of making heat-resistant castings in commonly used is silicon, aluminum, chromium, in use and oxygen reaction, the oxide layer will produce its compact and stable in the steel surface, which can protect the heat-resistant castings no longer oxidation. Chromium, silicon, aluminum addition high temperature oxidation, steel is good, but if too much amount of silicon, aluminum, mechanical properties and process of steel becomes worse. Therefore, heat-resistant steel with chrome as the main alloying elements in silicon, aluminum as auxiliary elements.
High strength heat-resistant castings mainly refers to the steel can be kept for a long time its ability to withstand mechanical loads at high temperature, the steel at high temperature under mechanical loading is the main softening and creep, the strength decreases with the increase of temperature, the latter in constant stress under the action of plastic deformation with time slowly increase, steel plastic deformation under high temperature is caused by intragranular slip and grain boundary sliding.
To improve the heat-resisting casting high temperature strength, alloying method is used. Also is added to the alloy elements in steel, improve the binding force between atoms and form a favorable organization. The addition of chromium, molybdenum, tungsten, vanadium, titanium, can strengthen the steel matrix, improve the recrystallization temperature, can also form a strengthening phase carbide or intermetallics.http://www.wuxiorient.com/