Requirements for chemical composition and oxidation environment of heat - resistant castings

- Feb 28, 2019-

In the process of using, heat-resistant casting mainly refers to steel with high-temperature oxidation resistance and high-temperature strength, and its high-temperature oxidation resistance is an important condition to ensure the workpiece to work under high temperature for a long time.In the oxidation environment such as high temperature air, the oxygen reacts with the steel surface to generate a variety of iron oxide layer, which is very loose and loses the original characteristics of the steel, easy to fall off.

 

In order to improve the oxidation resistance of steel at high temperature, alloying elements are added into the steel to change the structure of the oxide.Common alloying elements include chromium, silicon, aluminum, etc.They react with oxygen to form a dense, stable oxide layer, or passivation layer, on the surface of the steel, such as Cr2O3, SiO2 or Al2O3, to protect the steel from further oxidation.Chromium, silicon, aluminum to add more, steel high temperature oxidation resistance is good, so, heat resistant steel to chromium as the main alloy element, with silicon, aluminum as auxiliary elements, in short, steel high temperature oxidation resistance is only related to the chemical composition.

 

The high-temperature strength of heat-resistant casting is mainly to maintain the ability to withstand myocardial load for a long time at high temperature, and its equipment can withstand its mechanical load at high temperature.Second, creep, that is, under the action of constant stress, the plastic deformation increases slowly with time, and the plastic deformation of steel at high temperature is caused by the slip within the grain and the slip at the grain boundary.Alloying is usually used to improve the high temperature strength of steel.www.wuxiorient.com