Analysis of Common Defects and Causes of Steel Profile

Some common surface defects of steel profile are: folds, scratches, scars, pockmarks (pitting), pits, delamination, bulges and bubbles, torsion, corner dissatisfaction, etc.

1. Fold. Along the length direction of the steel, there are inclined cracks on the surface, which are called folds.

Folds on the steel surface can be removed by machining.

2. Scratches. In the process of production, transportation, etc., the groove marks formed by mechanical scratches on the surface of steel are called scratches.

3. Scarring. Tongue-like, nail-like or scale-like pieces on the steel surface are called scars. It is formed on the surface of the steel after being rolled by the metal shell and bumps splashed on the surface of the steel ingot.

4. Pitting. Pitting is the uneven rough surface of the steel surface.

5. Pit. Depressions that are periodically or irregularly distributed on the steel surface are called pits or pits.

6. Layering. Due to non-metallic inclusions, unwelded internal cracks, residual shrinkage cavities, pores, etc., the steel section after shearing is black lines or black bands, and the steel is separated into two or more layers, which is called delamination. 

7. Bubbles and bubbles. The surface of the steel is irregularly distributed circular protrusions, which are called bulges, and the edges of the bulges are relatively smooth. After the bulge bursts, a chicken claw-shaped crack or a tongue-shaped knot is formed, which is called a bubble.

8. Twisted bar steel has spiral twisting deformation along the longitudinal axis, which is called torsion. The torsion can be caused by improper installation or dislocation of the rolls, deflection and serious wear of the guide plate installation, improper adjustment of the rolling mill, uneven temperature of the rolled piece or uneven deformation resulting in inconsistent extension.

9. Angle dissatisfaction. The corners of the section steel are insufficient or not filled, and the defect of a round rough surface is called angle dissatisfaction. Examples include slump, obtuse, rounded corners. Incorrect pass design, severe pass and guide wear, improper adjustment, insufficient corner reduction, and poor operation can all produce such defects.