303 vs 304 / X5CrNi18-10: Same 18/8 base — 303 adds S for machinability at corrosion cost
303 vs 304 / X5CrNi18-10
Side-by-side chemical composition and mechanical property comparison.
Overview
303
1.4305
Free-machining austenitic stainless steel — the most machinable of all austenitic grades. 0.15-0.35% S (as MnS inclusions) provides excellent chip-breaking. Trade-off: lower corrosion resistance than 304, poor weldability (hot cracking risk), and not suitable for cold forming. Used for high-volume automatic lathe parts: fittings, valves, screws, shafts, and precision components.
304 / X5CrNi18-10
1.4301
The world's most widely used stainless steel — the original 18/8 austenitic. Good corrosion resistance in atmospheric, organic, and inorganic environments. Excellent formability and weldability. Not recommended for chloride-rich or marine environments (use 316L). Used in food processing, kitchen equipment, architecture, tanks, and general engineering.
| 303 | 304 / X5CrNi18-10 | |
|---|---|---|
| Material Number | 1.4305 | 1.4301 |
| Category | Stainless Steel | Stainless Steel |
| Standard | EN 10088-3 | EN 10088-2 |
Chemical composition (wt%)
| Element | 303 | 304 / X5CrNi18-10 | Overlap |
|---|---|---|---|
| C | 0–0.1% | 0–0.07% | OK |
| Si | 0–1% | 0–1% | OK |
| Mn | 0–2% | 0–2% | OK |
| P | 0–0.045% | 0–0.045% | OK |
Mechanical properties
| Property | 303 | 304 / X5CrNi18-10 | Unit |
|---|---|---|---|
| tensile_strength | 500–750 | 500–700 | MPa |
| yield_strength | ≥ 190 | ≥ 190 | MPa |
| elongation | ≥ 35 | ≥ 45 | % |
Compatibility Assessment
303 has 0.15-0.35% S giving 2-3x machining speed vs 304. But S reduces corrosion resistance (pitting at MnS sites) and makes welding problematic (hot cracking). Choose 303 for high-volume turned parts; 304 for welded structures and better corrosion.
Frequently Asked Questions
Is 303 the same as 304 / X5CrNi18-10?
303 and 304 / X5CrNi18-10 have a 70% composition overlap. Same 18/8 base — 303 adds S for machinability at corrosion cost
Can I replace 303 with 304 / X5CrNi18-10?
In many cases, yes. The compositions overlap significantly (70%). However, always verify mechanical property requirements and heat treatment compatibility for your specific application.
What is the difference between 303 and 304 / X5CrNi18-10?
The main differences are in the following elements: S, Cr. 303 is a Stainless Steel grade, while 304 / X5CrNi18-10 is a Stainless Steel grade.
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Data provided for reference only. Always verify against the applicable specification for critical applications.
All data is for reference only. Equivalents indicate similarity, not identity. Always verify against the applicable specification for safety-critical applications. materialref.com accepts no liability for decisions based on this data.