Spiral steel brittle fracture and component usage temperature. The study found that people when the temperature drops below a certain temperature, the material will be brittle transition state, the impact absorbed energy decreased, a phenomenon known as cold brittleness, high strength metal materials, low stress occurring in brittle fracture process, the material structure is far from homogeneous and isotropic. Tissues 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 to select members with appropriate cold brittle transition temperature of the material.
The above formula, the excitation frequency of the excitation circuit capacitance, inductance is inversely proportional to the square root, or the voltage and current proportional to the square, as long as the change in the circuit capacitance, inductance, or voltage and current can change the size of the excitation frequency, so as to achieve control of welding temperature. For low carbon steel, welding temperature control in the 1250 ~ 1460 ℃, can meet the pipe wall thickness 3 ~ 5mm penetration requirements. In addition, the soldering temperature can be achieved by adjusting the welding speed.
Spiral steel pipe drawing, due to the presence of hot tube defects such as cracks, or high-precision drawing after the tank is made, in the course of the fracture occurred, almost no plastic deformation occurs, in general are brittle fracture. Brittle fracture is 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 of the cross-variable loads, can also cause fatigue fracture phenomena.
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