Which Stainless Steel Grade Is Best? 304 vs 316 Stainless Steel Explained

Choisir le wrong stainless steel costs money and credibility—rusted welds, failed pumps, product recalls. Relax: the right grade stainless prevents corrosion headaches, saves budgets, and earns repeat customers.

Les meilleur acier inoxydable depends on environment. Acier inoxydable 304 suits indoor, mildly corrosive, or food‑contact uses. Acier inoxydable 316—with molybdenum—delivers superior corrosion resistance against chlorides, acids, and high temperatures, making it ideal for marine, chemical, and pharmaceutical applications. Match grade to exposure, temperature, and budget.

Article Outline

1. What Makes Stainless Steel Resist Rust and Corrosion?
2. Deep Dive into 304 Stainless Steel—The Versatile Workhorse
3. Pourquoi 316 Stainless Steel Excels in Chloride‑Rich Environments
4. 304 vs 316: Cost, Strength & Résistance à la corrosion (Interactive Chart)
5. Beyond Austenitic: Acier inoxydable duplex & 430 Magnetic Stainless
6. How Chromium, Nickel & Molybdenum Shape Corrosion Resistance
7. Food‑Grade & Stainless Steel Cookware Essentials
8. Welding, Machining & Fabrication Best Practices
9. Project‑Selection Checklist: Picking the Right Stainless Steel
10. Market Trends & Pricing Outlook (2025‑2027)

1 What Makes Stainless Steel Resist Corrosion?

Stainless steel is an alloy of iron plus ≥ 10.5 % chromium and controlled nickel. Chromium reacts with oxygen, forming a self‑healing oxide film that withstands scratches and harsh chemicals. Additives such as molybdène or nitrogen* boost resistance to pitting.

Industry stat: Global stainless output hit 62.6 million t in 2024—up 7 % YoY. China alone poured 39.4 Mt. (worldstainless)

Need deeper chemistry tables? Visit  stainless steel grade guide.

2 Deep Dive into 304 Stainless Steel

Acier inoxydable 304—an austenitic stainless steel with chromium and 8 % nickel—is the most commonly used stainless steel for:

• Transformation des aliments lines and kitchen equipment
• Structural tubing (see  stainless steel tube size chart)
• Architectural handrails and high‑end cookware

304 offers:

• Balanced strength vs. cost (≈ $2 200 t FOB China, 2025Q1)
• High corrosion resistance in fresh‑water & mild acidic media
• Easy weld & formability—ideal for complex OEM housings

Case study – A beverage OEM swapped carbon steel skids for 304. Maintenance hours fell 22 % over 12 months, ROI in 8 months.

3 Why 316 Stainless Steel Excels in Chloride‑Rich Sites

Add 2–3 % molybdenum and ≥ 10 % teneur en nickel: Acier inoxydable 316 leaps ahead with superior corrosion resistance.

Perfect for:

• Marine environment hardware—jetty bolts, pump shafts
• Chemical processing—acid reactors, pipe spools
• Food‑grade stainless steel tanks for brined cheeses, soy sauce

Seawater contains ~19 000 ppm chloride ions—enough to pit 304 in weeks.
In a Red‑Sea desalination plant, our grade 316 stainless pipes ran 5 years leak‑free versus competitors’ 304 which failed at year 2.

Need polished sanitary 316 tube? See  316 cost analysis.

4 304 vs 316: Performance Chart

Quick Takeaways

• Coût: 304 < 316 (≈ 12 % cheaper).
• Resistance to corrosion: 316 wins, especially against chloride & acid environments.
• Strength difference minimal in annealed state; both can withstand high loads when cold‑worked.

5 Beyond Austenitic: Duplex & 430 Magnetic Stainless

Acier inoxydable duplex

Mixes austenitic stainless et ferritic stainless steel phases:

• Twice yield strength of 304
• Outstanding resistance to pitting under stress
• Popular in offshore rigs & pressure vessels

Learn more in our duplex stainless overview.

430 Stainless – The Magnetic Stainless Alternative

Low‑nickel 430 stainless steel is magnetic stainless, budget‑friendly, yet less resistant than 304.

Need cold‑rolled coils? Check our 430 coil inventory.

6 How Chromium, Nickel & Molybdenum Shape Corrosion Resistance

Small tweaks in chemistry deliver big performance jumps. Chromium builds the passive film; nickel stabilises the austenitic stainless matrix; molybdène tightens the lattice, offering superior corrosion resistance in acids and brine.

Highlights

• Raise chromium above 20 % and pitting plummets by 50 %.
• Nickel content > 10 % keeps steel non‑magnetic and ductile at ‑196 °C.
• A mere 2 % molybdenum doubles resistance to pitting in sea‑water tests.

7 Food‑Grade & Stainless Steel Cookware Essentials

Chefs, dairy engineers, and brewery owners value food grade stainless steel because it neither reacts with acids nor sheds flavour‑spoiling ions.

Common Food‑Contact Grades

“Switching to 316 SS cut brine‑tank failures from yearly to once a decade.” – QA Manager, condiment factory

8 Welding, Machining & Fabrication Best Practices

Keep your projects crack‑free and hygienic.

• Weld with low‑carbon fillers (e.g., ER308L or ER316L) to avoid carbide precipitation.
• Post‑weld passivation using nitric‑citric blend restores the protective film.
• For ferritic or duplex stainless steel, limit heat input to <1 kJ/mm to maintain phase balance.
• Use carbide or cermet tooling at 30 m/min—stainless steel is highly resistant to abrasion.

Need laser‑cut blanks fast? Tap our CNC fabrication service—48‑hour turnaround for up to 20 mm plate.

9 Project‑Selection Checklist: Picking the Right Stainless Steel

Remember: Les grade of stainless steel shapes lifetime cost more than purchase price. Select once. Save forever.

10 Market Trends & Pricing Outlook (2025‑2027)

• Nickel LME price averaged $18 200 t in H1 2025; analysts foresee a 7 % rise as EV‑battery demand meets constrained supply.
• China’s stainless melt shops target high‑end cookware and EV tube lines; expect tighter spreads between 304 vs 316.
• Carbon border taxes in the EU could add €110 t on imported slabs—another reason to source finished, value‑added products direct from our mill.

FAQ

How does grade 304 SS differ from grade 430 stainless?
304 is austenitic stainless, non‑magnetic, higher nickel, better la résistance à la corrosion. 430 is ferritic stainless steel, magnetic, cheaper, but less resistant to salt.

Is duplex stainless steel difficult to weld?
Not if you keep heat input low and use matching duplex filler; the balanced microstructure retains strength and resistance to oxidation.

Can I replace carbon steel with stainless and skip painting?
Yes—stainless steel is a versatile material that forms a protective film, so no paint needed; overall lifecycle cost drops.

Why is 316 SS called marine grade?
Its molybdène addition offers excellente résistance à la corrosion in seawater, outperforming 304 by 10× in ASTM G48 tests.

Which stainless steel type handles both high acidity and high temperature?
316 SS ou duplex grades with added molybdenum—making it suitable for pressure cookers and acidic CIP cycles.

How do surface finishes affect hygiene?
A 2B or BA finish keeps the surface of stainless steel smoother; bacteria adhesion falls 60 % compared to mill‑scale plate.

🚀 Key Takeaways

• Stainless steel is one family, many types and grades.
• 304 offers affordability; Acier inoxydable 316 brings better than 304 chloride defence.
• For loads + corrosion, duplex stainless steel leads.
• Chemistry tweaks—chromium, nickel, molybdène—unlock high corrosion resistance and strength.
• Still unsure? Email our engineers, attach your drawing, and we’ll match the right stainless steel in 24 h.