In the case of strict control of smelting, there may be layers for sawing steel tube defects. The control measures are as follows:
1. Improving the Toughness of Plastic Pipe
Improve the cleanliness of molten steel, reduce harmful inclusions; increase the proportion of crystal axis, reduce central segregation and central porosity; use a reasonable cooling system to avoid cracks in slab; slab or rolling assembly line adopt slab cooling process 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.
3. Reduce rolling speed
Roll speed is a key parameter of piercing process. The critical roll speed of stratification begins to appear in the transition process of roll speed from low to high. It is easy to form tube holes by reducing roll speed, and easy to form lamination defects by capillary at higher roll speed. In order to eliminate capillary and lamination defects, roll speed should be reduced to the critical lamination speed or lower beginning.