High Temperature Instantaneous Tensile and Creep Properties of AISI321 Alloy
Alloy AISI321 is a common stainless steel, specific natural stainless steel. It is a stable material also recommends for high temperature applications due to its good mechanical properties and corrosion resistance. It is also one of the most widely used materials in the aerospace and oil & gas industry. It is often used in components and structures which are exposed to high temperatures, such as parts coming directly in contact with hot gases, such as gas turbine blades. Therefore, an accurate knowledge of its high temperature properties is required for reliable structural design.
The instantaneous tensile properties of charpy AISI321 stainless steels at room temperature and high temperature up to 100°C were studied. The loading rate and strain rate of specimen are controlled by a slow-stretching machine. The experimental results show that room temperature Ultimate Tensile Stress (UTS) decreases with increasing test temperature, while the elongation increases with increasing temperature, which is consistent with the general trend of the tensile properties of other stainless steels. Comparing test temperatures up to 100°C, there is a clear difference in strength and plasticity, although it still has a certain strength and plasticity even at high temperature 100°C.
Futhermore, creep properties of AISI321 stainless steel are researched at temperatures 850~1050°C, under a wide range of constant loading rate from 0.1 to 10MPa/s. To simulate the long-term thermal exposure, 10mins long-term creep testing is performed, and samples are prepared with a solution heat treatment followed by a quenching and aging. The creep rupture strength decreases with increasing test temperature and loading rate, and further decreases with testing time. According to the experimental results, the creep deformation causes the primary mode of failure of the AISI321 stainless steel at temperatures from 850°C to 1050°C.
When using this kind of material at high temperature for a long period of time, creep failure should be avoided. Therefore, the application of this material is limited to 623K and in a short time. At the same time, its mechanical properties can be improved by adopting suitable heat treatment processes.
In conclusion, this paper has introduced the high temperature instantaneous tensile and creep properties of the AISI321 alloy. It is found that the tensile properties vary with temperature while the creep properties are affected more seriously by test temperature, loading rate and testing time. This could be used as a reference for the design of structures and components which are exposed to high temperatures.
