Lamination Defect Control Measures of LSAW and DSAW Steel Pipe

Lamination defect control measures of DSAW steel pipe is following below:
1, to improve the toughness of plastic tube
Improve the cleanliness of molten steel, to reduce the harmful inclusions; increase the proportion of the slab crystal axis, to reduce the center segregation and center porosity; the use of reasonable cooling system to avoid cracks occur within the slab; billet or rolling slab to be taken offline slow cooling process, reduce internal stress, thus ensuring the microstructure and mechanical properties of the finished tube and pipe meet the technical standards.

2, the reasonable control of the heating temperature
By measuring the thermoplastic curve, choose the best heating temperature. Note also that there is enough heating tube holding time, in order to reduce and improve plastic deformation resistance and toughness.
 
3, lower roll speed
Roll speed is a key parameter piercing process, the roll speed from low to high variations in the process, there is a critical stratification began the roll speed. Lower roll speed, easy to form tube bore; higher roll speed, tube and capillary easily form a layered defects. In order to eliminate delamination defects and capillary tube, roll speed should be reduced to the beginning of the critical delamination roll speed of these mild steel pipe.