1. ASTM A53 thick wall seamless steel tube hot rolling position away from the steel head 38118m, mainly located in the middle of the steel strip.
2. it is speculated that the gap formed by the rolling force and shear force during the rolling process is macroscopically large, so the gap begins in the middle of the strip width.
3. seamless steel pipe is smooth in the cold rolling process, and there is no obvious defect on the surface before and after fracture.
The microstructure of fracture surface was observed and typical ductile ductile fracture morphology was observed. At the same time, the faults are distributed in layers, the central pits are larger, the pits are narrowed near the surface, the cracks appear in the center and the depth of the central fracture is deep, and the stratified topography is closely related to the central isolation.
ASTM A53 thick wall seamless steel pipe analysis:
1. the surface morphology of hot rolled and cold-rolled steel tubes was observed under scanning electron microscope, and cracks were observed in the middle of the fracture.
2, the results show that there are obvious oxide particles near the crack, and there is a complete polygonal ferrite shape near the crack near the crack.
3, the characteristics of 30um oxidation particles near cracks are closely related to the original defects of continuous casting billets. The continuous casting slab is heated for a long time in the heating furnace, so that the elements near the crack are oxidized to form a thicker oxide layer. Inherit the last volume.
The results show that there are obvious cracks and oxidation zones at the center of thickness and 1/4, and there are also oxide particles near the crack.
