In general, the hydraulic (pneumatic) part is assumed to be uniform, continuous and isotropic when planning the use of mechanical properties, which is safe by analysis and sometimes has unexpected consequences for the spiral steel pipe Fault cracking attack.
The study found that the use of brittle fracture is also related to the temperature. After discussion, we found that when the temperature is lower than a certain temperature, the brittle material will change the status quo and the impact absorption energy will decrease, which means that the cold brittle and high strength metal resources are guessing the stress cracking and brittle cracking process, the data arrangement is not Uniform, isotropic. Arranging cracks, there will be inclusions, pores and other defects, you can invest to speculate that the micro-cracks. Therefore, even in the program according to the components of the operating temperature to select the appropriate cold brittle temperature change information.
Coil frequency and circuit capacitance, inductance and square root inversely proportional to the voltage or current may be proportional to the square root, just change the circuit capacitance, inductance or voltage, you can change the current frequency of the size, and then reached the intent of the welding temperature control . Low-carbon steel welding temperature control between 1250 ~ 1460 °, to meet the wall thickness of 3 ~ 5mm penetration requirements. In addition, the welding temperature welding speed can also be completed by the end of the schedule.
Spiral steel pipe cold drawn, hot-rolled pipe cracks and other defects or high-precision drawing tank cracking in the course of use, almost no plastic deformation brittle fracture. Brittle cracking is caused by a variety of reasons. Such as: the grain boundary separation method, regardless of its strength than the matrix strength or weakness, is the cause of the fracture; inclusions grain boundary segregation is the cause of cracking; In addition, even in far below the yield load of alternating loads , Will also lead to the emergence of fatigue cracks.
The main frequency of the eddy current heating power affected by the welding temperature of the spiral welded pipe is influenced by the high frequency eddy current heating power of the primary current frequency and the square of the mixing frequency of the eddy current heating power proportional to the current; and by stirring and stirring the current frequency and voltage, current and capacitance , The impact of inductance.
When the helical tube heat input is insufficient, the weld edge is heated to a temperature below the weld metal arrangement, still remains in solid form incomplete fusion or penetration; when the heat input is insufficient, the weld edge is heated beyond the welding temperature, causing Burn or droplet welded to form caves.
