Super detailed introduction on stainless steel

2025-03-26

Stainless steel roll steel classification table

Material type	Chinese brand (GB)	American grade (AISI/SAE)	European Brand (EN)	Main characteristics	Typical use
Austenitic stainless steel	06Cr19Ni10 (304)	304	1.4301	Corrosion-resistant, non-magnetic, easy to process	Food equipment, building decoration, elevator board
	06Cr17Ni12Mo2 (316)	316	1.4401	Acid and alkali resistance (including Mo), pitting resistance	Chemical industry, Marine environment, medical equipment
	022Cr17Ni12Mo2 (316L)	316L	1.4404	Ultra-low carbon, resistance to intergranular corrosion after welding	Nuclear power, oil pipelines
Ferrite stainless steel	10Cr17 (430)	430	1.4016	Magnetic, oxidation resistant, low cost	Home appliance shell, kitchenware, automobile exhaust pipe
	022Cr18Ti (439)	439	1.4510	High temperature oxidation resistance, good weldability	Automobile exhaust system, water heater liner
Martensitic stainless steel	12Cr13 (410)	410	1.4006	High strength, heat treatment, wear resistance	Tools, bearings, mechanical parts
	20Cr13 (420)	420	1.4021	High hardness, good polishing	Surgical instruments, tableware
Duplex stainless steel	022Cr23Ni5Mo3N (2205)	2205	1.4462	High strength + high corrosion resistance (austenite + ferrite mix)	Chemical storage tank, seawater treatment equipment
	022Cr25Ni7Mo4N (2507)	2507	1.4410	Super duplex steel, resistant to chloride corrosion	Oil platform, desalination equipment
Precipitation hardened stainless steel	07Cr17Ni7Al (631)	17-4PH	1.4542	Can be strengthened by heat treatment, high strength	Aerospace, precision instrument parts

Stainless steel roll steel classification table

Surface treatment type	Code/name	Process specification	peculiarity	Typical use
Cold-rolled surface	2B (Cold rolled bright finish)	After cold rolling, it is annealed, pickling, and finally rolled lightly with a flat roll	Smooth reflective, light matte, most commonly used	Architectural decoration, home appliances, elevator panels
	BA (Bright annealing)	Annealing in hydrogen or vacuum environment to retain the high gloss after rolling	High reflectivity, no oxide skin, close to mirror	High-end electrical appliances, mirror substrates
	No.1 (Hot rolling, annealing and pickling)	Hot rolling backfire and pickling to remove the oxide layer	Rough and dull, low cost	Industrial structural parts, chemical equipment
Mechanical polishing	No.3 (Rough sanding)	Polishing with 100~120 mesh grinding material	Visible uniform abrasion, semi-matte finish	Kitchen equipment, industrial parts
	No.4 (Drawing)	One-way polishing with 150~180 mesh grinding belt	Fine stripes, anti-fingerprint, commonly used	Elevator interior, home appliance panel
	HL (Scrub)	Cross polishing to form a non-directional texture	Matte, wear resistant, hidden scratches	Building exterior walls, rail transit
Mirror finish	6K (Ordinary mirror)	First polishing with coarse abrasive, and then fine abrasive (such as diamond plaster) polishing	high reflectivity, but there may be fine lines	Decorative decoration, luxury display cases
	8K (Super mirror)	Multi-pass precision polishing to flawless	Close to glass mirror effect	High-end hotels, art installations
Special treatment	Embossed	By rolling out three-dimensional patterns (such as diamond, leather pattern)	decorative strong, non-slip	Decoration, furniture, ship interior
	Color coating (PVD/ electroplating)	Vacuum ion coating or electroplating coloring (titanium, rose gold, etc.)	corrosion resistance, rich color	Luxury goods, iconic buildings
	Sandblasting	High speed spray sand particles to form a uniform rough surface	Matte texture, anti-glare	Industrial equipment, outdoor facilities
	Etching	Chemical or laser etching of patterns/text	Customized pattern, permanent retention	Brand identity, artistic creation
Functional processing	AFCoating	Nanometer coating reduces fingerprint residue	Easy to clean and keep beautiful	Electronic devices, high frequency touch areas
	Passivation	Nitric or citric acid treatment enhances the oxide film	Improved corrosion resistance	Medical equipment, food industry

Stainless steel production process

1. Prepare raw materials
Main raw materials:
Iron ore or steel scrap (recycled)
Alloying elements: Chromium (Cr, ≥10.5%), nickel (Ni), molybdenum (Mo), manganese (Mn), etc
Flux: limestone (CaO), fluorite (CaF₂), etc. (for desulfurization, dephosphorization)
2. Smelting process
Stainless steel smelting usually adopts the "three-step method" (blast furnace/electric furnace → AOD/VOD refining → continuous casting) :
Primary refining (EAF or converter) :
Electric arc Furnace (EAF) : Melting scrap steel and alloys, suitable for small batch, high alloy steel (e.g. 316L).
Converter: For mass production (e.g. 304), the cost is lower.
Refining (key step) :
AOD (argon-oxygen decarburization) : By blowing into argon-oxygen mixture gas to reduce carbon content, while reducing chromium oxidation (suitable for 300 series austenitic steel).
VOD (Vacuum oxygen decarbonization) : Decarbonized in a vacuum environment, suitable for ultra-low carbon stainless steel (such as 316L).
Continuous Casting:
Molten steel is cast into slab, square or round billet (thickness 150~250mm).
3. Hot rolling
Heating furnace: slab heating to 1100~1250℃.
Roughing + finishing rolling: the slab is rolled into hot rolled coil (thickness 2~10mm) through multiple rolling.
Pickling: Remove the surface oxide (nitric acid + hydrofluoric acid mixture).
4. Cold rolling (precision thickness control)
Cold rolling machine: rolling at room temperature, the thickness can be reduced to 0.3~3mm, the surface is smoother.
Annealing: removal of work hardening (protection of atmosphere against oxidation).
Second pickling: Ensure clean surface.
5. Surface treatment
2B surface: cold rolling + annealing + pickling + light rolling (most commonly used).
BA mirror: bright annealed, no oxidation.
No.4 Wire drawing /HL scrub: Mechanical polishing or sandblasting.
6. Finished product processing
Stripe: Cut into different widths according to customer requirements.
Cutting/stamping: making plates, pipes, parts, etc.