Generally speaking, the hydraulic (pneumatic) part assumes that the data are uniform, continuous and isotropic when planning to use mechanical properties. The analysis based on this method is safe, and the plan sometimes presents cracking attack of unexpected failure of spiral steel tube.


It is found that the brittle crack is also a member of the relevant temperature. After discussion, we find that when the temperature drops below a certain temperature, the brittle material will change this situation and the impact absorption energy decreases. This performance is called cold brittleness. High strength metal resources guess the process of low stress brittle cracking. The data arrangement is far from uniform and isotropic. Arrangements with cracks, inclusions, stomata and other shortcomings can be funded to look at speculative microcracks. Therefore, even if the program chooses the appropriate cold brittle temperature change information according to the working temperature of the component.


The frequency and capacitance of the helical tube are inversely proportional to the square root of the circuit, and the inductance is possibly proportional to the square root of the voltage and current. Only by changing the capacitance, inductance or voltage of the circuit, the current frequency can be changed, and then the intention of welding temperature control can be achieved. The welding temperature of low carbon steel is controlled at 1250 ~ 1460 C, which can meet the penetration requirement of 3 ~ 5mm thickness of pipe wall. In addition, the welding temperature and speed can also be completed by scheduling.


When the spiral steel pipe is cold drawn, hot-rolled pipe cracks and other shortcomings or high-precision wire drawing tank cracks occur in the application attack process, there are almost no plastic deformation events, usually brittle cracks. Brittle cracks are caused by many reasons. For example, grain boundary segregation, whether its strength is stronger than matrix strength or weaker, is the cause of cracks; grain boundary segregation of inclusions is the cause of cracks; in addition, even under alternating loads far below yield limit, fatigue cracks will occur.


The welding temperature of helical tube affects the main frequency eddy current heating power, the high frequency eddy current heating power is affected by the primary current frequency, and the eddy current heating power is proportional to the frequency of the current stirring frequency; the current frequency of inductive stirring through stirring and voltage, current and capacitance.


When the spiral pipe lacks heat input, the edge of the weld is heated to a temperature lower than that of the welded metal arrangement, and the solids are still incompletely fused or penetrated. When heat input is lacking, the edge of the weld is heated beyond the welding temperature, and sintering or droplets form a molten hole.