1. Small longitudinal fissure
The length of the small longitudinal cracks on the surface of the DIN 1630 ST44.4 seamless steel pipe is less than 200mm, the width is less than 3mm, and the depth is less than 0.3mm.
2. Peak cracks
The cracks all occurred in the DIN 1630 ST44.4 seamless steel pipe at a distance of 5-60mm from the bottom surface to the edge, the macroscopic direction is perpendicular to the rolling direction, and it is in the shape of a mountain.
3. Cracks on the edge
This kind of crack mainly occurs at the distance of 20-80mm from the edge of the DIN 1630 ST44.4 seamless steel pipe. The shape is a number of parallel longitudinal cracks of different sizes. The rule is that the thicker the DIN 1630 ST44.4 seamless steel pipe specification, the wider. The more serious this defect.
4. Inclusions and scars
Inclusions and scars are regularly distributed, and the phenomenon is obvious after fine operations such as edge flame peeling crack inspection or casting slab scars flame cleaning.
