How much do you know about the production process of stainless steel?

Regarding the production process of stainless steel, I understand its key steps include:

1. Raw Material Preparation
   Primary components: iron, chromium (≥10.5%), nickel, molybdenum, etc., precisely proportioned for corrosion resistance and mechanical properties.

2. Melting

   • Electric Arc Furnace (EAF): Initial melting of scrap steel and alloys.

   • Argon Oxygen Decarburization (AOD): Inject argon-oxygen gas to reduce carbon while minimizing chromium loss.

   • Vacuum Oxygen Decarburization (VOD) (optional): Enhances purity for ultra-low carbon grades (e.g., 316L).

3. Casting
   Molten steel is formed into slabs via continuous casting or ingots via mold casting.

4. Hot Rolling
   Heated to 1100-1250°C and rolled into intermediate thickness plates/coils to refine grain structure.

5. Annealing & Pickling

   • Annealing: Stress relief and corrosion resistance restoration (e.g., solution treatment).

   • Pickling: Removes oxides using HNO3/HF solution to expose passivated surfaces.

6. Cold Rolling
   Rolled at room temperature to achieve thinner gauges (e.g., 0.3mm foil) with improved finish and strength.

7. Finishing & Surface Treatment

   • Polishing (Mirror/HL)

   • Coating (e.g., PVD)

   • Texturing (brushed, sandblasted)

8. Quality Control
   Compositional spectroscopy, metallography, salt spray testing, mechanical property verification.

Variants

• Duplex Stainless Steel: Requires controlled ferrite/austenite phase balance via specific heat treatment.

• Martensitic Stainless Steel: Involves quenching & tempering (e.g., 440C cutlery steel).