The study found that people when the temperature drops below a certain temperature value, the data will be found to brittle state, the impact absorbed energy decreased, a phenomenon known as cold brittleness, high strength metallic materials brittle fracture occurred in low stress process, the data is far from homogeneous isotropic tissue organization have cracks, there will be inclusions, porosity and other defects, which are a material can be seen in the micro-cracks. Therefore, the design also according to the operating temperature of components to select cold-brittle transition temperature with the appropriate information.
Generally data are assumed to be homogeneous isotropic continuous analysis that this approach is based on the design of safe, and sometimes accidental breakage incidents. As hot-rolled tube defects such as cracks or high-precision cold drawn tube is made after the tank, cold drawn seamless. Breakage occurs during use, almost no plastic deformation occurs, in general are brittle fracture. Brittle fracture caused by a variety of reasons, such as: precipitates on the grain boundaries, regardless of the intensity ratio of the matrix strength strong or weak, are all causes cracks; grain boundary segregation of inclusions also cause fracture; addition, even in far less than the yield limit alternating loads can also cause fatigue fracture phenomena.
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