Fracture of lsaw steel pipe, mechanical properties of hydraulic (pneumatic) parts used in design, brittle fracture is also related to the use temperature of the component.
It has been found through research that when the temperature is lower than a certain temperature value, it is found that the data will be transformed into a brittle state, and the impact absorption work is obviously reduced. This phenomenon is called cold brittleness, and low stress brittle fracture occurs in high-strength metal materials. In the process, the data organization is far from uniform and isotropic, there will be cracks, and there will be defects such as inclusions and pores. These defects can be regarded as microcracks in the material. Therefore, the design should also select the data with the appropriate cold-brittle transition temperature according to the working temperature of the component.
In general, it is assumed that the data is uniform and continuous isotropic. According to this method, the design is considered safe and sometimes accidental breakage occurs. Due to defects such as cracks in the hot-rolled billet or high-precision cold-drawn tubes being formed into cylinders, the
seamless steel tubes are cold-drawn. There is almost no plastic deformation occurring during the fracture during use, and it is generally brittle fracture.
Brittle fracture is caused by various reasons. For example, when there are precipitates on the grain boundary, whether the strength is stronger or weaker than the strength of the matrix, the crack is caused; the segregation of inclusions on the grain boundary is also the cause of the fracture; Even under the action of an alternating load far below the yield limit, fatigue fracture can occur.
