1. Pickling removes oxide scale (iron oxide scale) from precision steel pipes.
During hot rolling or annealing, a hard oxide scale (FeO, Fe₂O₃, Fe₃O₄) forms on the surface of precision steel pipes. This scale is very difficult to remove mechanically and affects the surface quality of the precision steel pipe. Pickling effectively dissolves these oxides, restoring the metallic luster to the surface.
2. Pickling improves surface quality to meet “precision” requirements. Precision steel pipes emphasize high accuracy in outer and inner diameters and a smooth surface. If the oxide scale is not removed, it will cause a rough appearance, uneven wall thickness, inaccurate measurements, and difficulty in controlling surface defects (pitting, indentations). After pickling, the surface of the precision steel pipe is clean and uniform, which is beneficial to achieving precision standards.
3. Pickling reduces frictional damage during cold working (drawing/rolling).
Precision steel pipes typically undergo cold drawing and cold rolling processes to achieve greater dimensional accuracy. If the surface of a precision steel pipe has oxide scale, it can lead to scratches, rolling marks, and increased fracture stress during cold working. Pickling precision steel pipes can avoid these problems, making the processing smoother.
4. Pickling precision steel pipes facilitates subsequent oiling, rust prevention, and phosphating. A clean, highly reactive surface after pickling is beneficial for: even application of rust-preventive oil, phosphating as a lubricating layer, and better adhesion of subsequent heat treatments or coatings. This is a crucial step in ensuring the long-term stability of precision steel pipes.
5. Pickling precision steel pipes removes rust and surface contaminants.
Besides oxide scale, pickling precision steel pipes can also remove: rust layers, dirt acquired during transportation, and metal powder. This ensures consistent and stable surface quality of the precision steel pipe.
In short, pickling precision steel pipes is necessary to remove oxide scale, improve precision, enhance processing performance, and guarantee surface quality and corrosion resistance.
Post time: Dec-11-2025