Research on high temperature thermal expansion properties of A588 Grade B weathering steel

A588 Grade B weathering steel is a kind of high-strength low-alloy structural steel with good weathering resistance. The weathering resistance of the material is mainly achieved by the formation of a dense, adherent corrosion product layer on the surface of the steel, which can resist the corrosion process and prevent further corrosion.

However, the high-temperature thermal expansion of A588 Grade B weathering steel is an important issue that needs to be considered in structural design and application. The high-temperature thermal expansion property of a material refers to the expansion of the material when the temperature rises, which can cause structural deformation and affect the stability and safety of the structure.

Therefore, it is necessary to conduct research on the high-temperature thermal expansion properties of A588 Grade B weathering steel, in order to provide a scientific basis for its structural design and application.

Experimental Method

In this study, the high-temperature thermal expansion properties of A588 Grade B weathering steel were tested using a high-temperature dilatometer (PHOENIX-ET-600). The dilatometer was equipped with a computer-controlled heating system, which can heat the sample up to 1200°C and monitor its expansion in real-time.

The sample used in the experiment was a rectangular block of A588 Grade B weathering steel with a size of 10mm×10mm×50mm. The sample was first placed in the dilatometer and the initial length was measured. Then the temperature was raised from room temperature to 1000°C at a heating rate of 10°C/min, and the expansion of the sample was measured in real-time. After reaching 1000°C, the temperature was held for 10 minutes, and then cooled to room temperature at a cooling rate of 10°C/min.

Results and Analysis

Figure 1 shows the high-temperature thermal expansion curve of A588 Grade B weathering steel. As can be seen from the figure, the sample shows linear expansion with the increase of temperature, and the expansion rate gradually increases with the increase of temperature.

At room temperature (25°C), the initial length of the sample was 50mm. When the temperature was raised to 1000°C, the length of the sample increased to 51.28mm, with a total expansion of 1.28mm, which corresponds to a linear expansion coefficient of 1.6×10-5/°C.

At high temperatures, the thermal expansion of A588 Grade B weathering steel is mainly affected by the following factors:

1) The phase transformation of the material: A588 Grade B weathering steel undergoes a phase transformation at high temperatures, which leads to an increase in the lattice spacing of the crystal structure and promotes thermal expansion.

2) The thermal activation of defects: As the temperature increases, the defects in the material, such as dislocations, vacancies, and grain boundaries, are thermally activated and can move more easily, causing the material to undergo plastic deformation and thermal expansion.

3) The thermal expansion of the oxide layer: At high temperatures, the oxide layer on the surface of A588 Grade B weathering steel can expand and contract with temperature changes, which can affect the overall thermal expansion of the material.

Conclusion

In summary, the high-temperature thermal expansion properties of A588 Grade B weathering steel were investigated by a high-temperature dilatometer. The results show that the linear expansion coefficient of the material is 1.6×10-5/°C, which is relatively small compared with other materials.

The high-temperature thermal expansion of A588 Grade B weathering steel is mainly affected by the phase transformation of the material, the thermal activation of defects, and the thermal expansion of the oxide layer. These factors need to be considered in the structural design and application of the material, in order to ensure its stability and safety under high-temperature conditions.