The control measures for lamination defects of spiral steel tubes are as follows:
1. Improving the Toughness of Plastic Pipe
Improve the cleanliness of molten steel, reduce harmful inclusions; increase the proportion of slab crystal axis, reduce central segregation and central porosity; use reasonable cooling system to avoid cracks in slab; adopt off-line slow cooling process for slab or rolling slab to reduce internal stress, so as to ensure that the structure and mechanical properties of finished pipe meet technical standards.


2. Reasonable control of heating temperature
The optimum heating temperature was selected by measuring the thermoplastic curve. Attention should also be paid to the sufficient holding time of heating pipes to reduce and improve the plastic deformation resistance and toughness.
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3. Reduce rolling speed
Roll speed is the key parameter in piercing process. In the process of changing the roll speed from low to high, there is a critical stratification to start the roll speed. It is easy to form pipe holes by reducing roll speed, and easy to form layered defects by high roll speed and capillary. In order to eliminate delamination defects and capillaries, roll speed should be reduced to the beginning or lower of critical delamination roll speed.