Fracture of longitudinal welded pipe: It was found through the study found that when the temperature is lower than a particular temperature value, the data will be changed to brittle state, the impact absorption work decreased significantly, a phenomenon known as cold and brittle, high-strength metal materials The data organization is far from uniform isotropic tissue will have cracks, there will be inclusions, pores and other defects, these defects can be seen as micro-cracks in the material. Therefore, the design should also be based on the operating temperature of the component to select the appropriate data of the cold and brittle transition temperature.
In general, it is assumed that the data is uniform and continuous isotropic. According to this method, the design is considered to be safe, and accidental breakage may occur. Due to defects such as cracks in hot-rolled tube or high-precision cold drawn tube is made cylinder, seamless steel tube cold drawn. The use of the process of fracture, almost no plastic deformation occurs, are generally brittle fracture.
Brittle fracture is caused by a variety of reasons such as: grain boundary precipitates, regardless of its strength than the matrix strength of strong or weak, are the reasons for the occurrence of cracks; grain boundary inclusions segregation is the cause of fracture; In addition, Even in the far less than the yield limit of the alternating load, it will cause the occurrence of fatigue fracture phenomenon.
