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Surface treatment method and effect of stainless steel pipe

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Surface treatment method and effect of stainless steel pipe

Five different uses of stainless steel pipe surface treatment

Stainless steel pipe finishes vary by environment. Understanding the impact of the environment on stainless steel pipes helps us to choose the right type of stainless steel pipes, otherwise stainless steel pipes will also rust and corrode.

Different stainless steel pipes require different surface treatments, such as:

• Pickling finish or sandblasting finish of stainless steel seamless pipes (industrial use);

• Polished surface of stainless steel sanitary pipes (seamless);

• Polished surface of small diameter stainless steel welded pipe;

• Pickling surface treatment or sandblasting of stainless steel welded pipes (industrial use);

• Internal and external polishing (welding) of stainless steel sanitary pipes.

Stainless steel pipe surface pretreatment

Pickling, chemical brightening, electrochemical polishing, electroplating, passivation, black coating, color coating, chemical processing, and other pretreatments are important steps in the surface treatment of stainless steel pipes.

Before the stainless steel tube is formed, the surface may have oil, burrs, uneven surface and oxide, so these defects should be removed before surface treatment.

The dirt that needs to be removed from the surface of the two stainless steel pipes

Stainless steel welded pipe surface treatment
The dirt that needs to be removed from the surface of the stainless steel pipe can be divided into organic matter and inorganic matter. -

Organics include mineral oils such as diesel, motor oil, petrolatum, paraffin, animal oils, and vegetable oils such as soybean, camellia, rapeseed, lard, and tallow. Oil stains are mainly lubricating oil, cutting oil, quenching oil, polishing oil, or fingerprints generated during the processing of stainless steel pipes.

Inorganic substances include soil, dust, compounds, etc. generated during heat treatment.

4 stainless steel pipe pretreatment procedures

  1. Polishing: remove the surface roughness of stainless steel, mechanically grind and polish to a certain surface finish;
  2. Degreasing: remove surface oil;
  3. Pickling: remove surface oxides;
  4. Weak corrosion: activate the surface to be treated, remove the surface passivation film, and expose the metal crystal structure.

5 kinds of stainless steel surface treatment methods:

  • Mechanical method: Use a polisher or other machine to remove surface roughness.
  • Chemical method: degreasing with an alkaline solution, pickling with an acid solution, dissolving grease, and descaling with an organic solvent.
  • Electrochemical Process: Use electrochemistry to remove oil and perform electrochemical etching.
  • Rolling light: centrifugal rolling light, centrifugal disc light, rotating light, suitable for small pieces with flattening and rust removal effect.
  • Sandblasting treatment: suitable for extensive area treatment, with the effect of decontamination and scale removal.

Therefore, an appropriate method should be selected according to the surface state of the stainless steel pipe and subsequent quality requirements.

Further reading

Stainless steel

As a special steel product with added value, stainless steel is used in more and more fields, whether it is in civil fields such as decoration, kitchen utensils, household appliances, etc.;
Or industrial fields such as petrochemicals, machinery, and equipment have been widely used, and the current market prospects for high-quality stainless steel products are still optimistic.

Seven common elements and their roles in stainless steel

Let’s take a look at the functions of the main related elements required for the production of stainless steel

  • Nickel: The most important core element of nickel-based stainless steel, which can improve the strength and toughness of the steel and improve its hardenability. When the content is high, some physical properties of steel and alloys can be significantly changed, and the corrosion resistance of steel can be improved.
  • Manganese: It can improve the strength of steel, weaken and eliminate the adverse effects of sulfur, and improve the hardenability of steel. High-alloy steel (high-manganese steel) with high manganese content has good wear resistance and other physical properties.
  • Chromium: It can improve the hardenability and wear resistance of steel, and can improve the corrosion resistance and oxidation resistance of steel.
  • Vanadium: It can refine the grain structure of steel and improve the strength, toughness, and wear resistance of steel. When it melts into austenite at high temperatures, it can increase the hardenability of steel; on the contrary, when it exists in carbide form, it will reduce its hardenability.
  • Molybdenum: It can significantly improve the hardenability and thermal strength of steel, prevent temper brittleness and improve remanence and coercive force.
  • Titanium: It can refine the grain structure of steel, thereby improving the strength and toughness of steel. In stainless steel, titanium can eliminate or reduce the intergranular corrosion phenomenon of steel.
  • Copper: Its prominent role is to improve the atmospheric corrosion resistance of ordinary low-alloy steel, which is more obvious when used in combination with phosphorus.

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