Large Diameter Seamless Square Tube Material Reflects The Mechanical Performance Indicators

Due to the varying properties of seamless square tubes, the material exhibits different behaviors. Mechanical properties are based on static stress. Whether performing static tensile tests or hardness tests, the stress is applied slowly to the specimen or workpiece. However, in actual production, many workpieces are subjected to impact stress, meaning that the stress is applied at high speeds. Examples include the hook between train cars when the train starts or stops, gears shifting, and the stress on forging dies and punches during operation.

Impact stress differs from static stress in that static stress involves purely force, while impact stress involves not only force but also velocity. While measuring the impact stress on a workpiece under impact stress is extremely complex, it is more convenient to consider the issue from an energy perspective. Therefore, impact stress can be considered an energy stress.

Due to the varying properties of seamless square tubes, the material exhibits different behaviors. While the material's deformation and failure under impact still proceeds through three stages: elastic deformation, elastic deformation, and fracture. However, the loading rate significantly influences these three stages, particularly the deformation of the seamless tube. Because deformation of the material after being subjected to stress requires time, increasing the loading rate may prevent the material's deformation from developing sufficiently quickly. This manifests as a decrease in the material's deformation capacity and an increase in its microscopic deformation resistance, such as its elastic limit and yield point.

Secondly, the unevenness or localization of the plastic deformation under impact is more pronounced than under static loading. Deformation is likely confined to a small area, where cracks and fractures may occur. This uneven deformation further limits the development of the material's deformation. Therefore, in general, impacting seamless tubes tends to embrittle the material. Materials with large deformation capacity under static load may have very small deformation capacity under impact and show brittleness.