Study on Properties of SS400 Steel After High Temperature

Study on Properties of SS400 Steel After High Temperature

The study of high-temperature properties of current materials is one of the hot topics. The high-temperature properties of materials include the properties of materials at high temperatures and after high temperatures (cooling). At present, the research on the high temperature performance of steel mainly focuses on the study of mechanical properties at high temperatures. SS400 mild steel is a common carbon structural steel. Its yield value decreases as the thickness of the material increases. Because of the moderate carbon content, good comprehensive performance, the strength, plasticity and welding properties are well matched, and the application is the most extensive. Therefore, it is very important to carry out experimental research on the mechanical properties of SS400 steel after high temperature, so as to finally establish a relatively complete strain relationship for high temperature steel, between yield strength and heated temperature, ultimate strength and heated temperature, Poisson’s ratio of heated temperature, stress and tensile stress.

By observing the surface condition of the steel after high temperature, it is found that the surface color of the steel subjected to the high temperature of 200 ° C is substantially the same as that at normal temperature. Steel that have experienced high temperatures of 400°C to 500 °C have a reddish-brown surface. The higher the temperature, the darker the color. Steel with a high temperature of 700 °C, the surface color is reddish brown and slightly blue. The steel with a high temperature of 1000°C to 1100 °C has blue color on the surface, and the higher the temperature, the more serious the surface carbonization, and the carbonization is severely severed at 1100 °C. As the heating temperature of the steel increases, the yield strength and ultimate strength of the steel generally decrease after high temperature, while the elastic modulus and Poisson’s ratio remain basically unchanged.

Through the yield strength test of SS400 steel pipe and SS400 steel bar, the steel with high temperature below 400 °C has a small change in yield strength compared with normal temperature steel after cooling. Steel that have experienced high temperatures of 400°C to 700 °C have a lower yield strength than steel at room temperature after cooling. As the temperature increases, the yield strength of the steel decreases rapidly. At 1000 °C, the yield strength is only about 40% of that of normal temperature steel.

After high temperature, the mechanical properties of the steel gradually decrease with the increase of the heating temperature, but it does not change much with the extension of the constant temperature. The established yield strength-heating temperature, ultimate strength-heating temperature, Poisson’s ratio-stress ratio and tensile stress-strain relationship curve are in good agreement with the experimental data, which provides reference for the nonlinear analysis for SS400 steel under complicate stress by high temperature.