SUS304 vs AISI 304 Stainless Steel Bar: Are They the Same?
SUS304 and AISI 304 usually point to the same 304 stainless steel family, but bar buyers still need to confirm the order standard, MTC wording, size and tolerance.
Introduction
A buyer may ask for SUS304 stainless steel bar. Another drawing may say AISI 304 stainless steel bar. A certificate may show UNS S30400, EN 1.4301 or simply 304.
The real question is simple: are these names talking about the same material?
For most practical stainless steel bar buying, SUS304 and AISI 304 usually point to the same 304 austenitic stainless steel grade family. But that answer is not enough for a purchase order. The standard, bar form, size, finish, tolerance, MTC wording and end-user acceptance still have to line up.
Quick Answer: Are SUS304 and AISI 304 the Same?
Yes, in many buying situations, SUS304 and AISI 304 are treated as equivalent grade names for the 304 stainless steel family.
But they come from different naming systems. SUS304 is commonly used in the Japanese JIS system. AISI 304 is the American grade name many buyers use in drawings and daily sourcing language. When the order is for bar stock, the final purchase wording may also mention ASTM A276 304 stainless steel bar, JIS G4303 SUS304 stainless steel bar, UNS S30400, EN 1.4301 or GB/T 1220 06Cr19Ni10.
That is why a careful supplier should not stop at the grade name. A useful quote checks whether the requested grade name, standard, product form and MTC can match the buyer's documents.
Common 304 Grade Names Buyers May See
The table below is a practical naming map for 304 stainless steel bar buyers. It is not a replacement for the full standard.
| Naming System | Common Wording | What Buyers Should Check |
|---|---|---|
| Common grade name | 304 stainless steel | Good for quick discussion, but too general for final ordering |
| AISI / market wording | AISI 304 | Common in drawings, emails and buyer specifications |
| JIS | SUS304 | Common with Japanese drawings and many Southeast Asia factories |
| ASTM bar order wording | ASTM A276 304 stainless steel bar | Common for stainless steel bars and shapes |
| UNS | S30400 | Often appears on MTCs and technical cross-reference tables |
| EN | 1.4301 / X5CrNi18-10 | Common European equivalent wording |
| GB/T | 06Cr19Ni10 | Common China standard grade naming for 304 family material |
If a buyer searches for SUS304 round bar, ss 304 round bars or sus rod, the inquiry may still be about a straight 304 stainless steel round bar. The supplier should confirm the exact standard and dimensions before quoting.
Which Wording Should Buyers Use?
The best wording depends on the document the buyer needs to satisfy. If the drawing already names one standard, keep that wording in the inquiry instead of translating it too early.
| Buyer Situation | Better PO or Inquiry Wording | Why It Helps |
|---|---|---|
| Japanese drawing says SUS304 | SUS304 stainless steel round bar, JIS G4303 review, size and MTC required | Keeps the drawing language clear for Japanese-invested factories |
| General international bar order | ASTM A276 304 stainless steel round bar, diameter, finish and tolerance stated | Fits common stainless steel bar purchasing language |
| European project document | EN 1.4301 stainless steel bar, confirm bar standard and MTC wording | Helps align the quote with European document review |
| China stock or mill route review | 304 / 06Cr19Ni10 equivalent, MTC and heat number required | Useful when checking China stock while keeping document traceability |
| Buyer accepts several names | 304 stainless steel bar, SUS304 / AISI 304 equivalent acceptable, MTC required | Gives the supplier room to check available stock without hiding the document need |
This small wording step can prevent a common problem: the material is technically acceptable, but the receiving team rejects it because the PO, MTC and labels do not speak the same language.
Why Equivalent Does Not Mean Automatically Accepted
The word equivalent is useful, but it can also create mistakes.
Two grade names may belong to the same 304 family, but the buyer's project may still require one exact standard. A drawing may say JIS G4303. A purchasing team may ask for ASTM A276. A European customer may expect EN 1.4301. A factory may only accept the wording used in its internal approval system.
This matters because the material is not approved by the sales label alone. It is approved by the documents and the actual supplied product.
Before accepting a substitute name, check:
- the standard named by the drawing or purchase order
- chemical composition shown on the MTC
- mechanical test requirements, if they apply
- bar form and size description
- heat number traceability
- whether the end user accepts the equivalent wording
A supplier can say "SUS304 is equivalent to 304" in a normal conversation. For shipment approval, the buyer should still check the MTC and order documents.
What Bar Buyers Should Confirm Before Quotation
For stainless steel bar orders, grade naming is only the first line. The quote also depends on shape, size, finish and stock route.
A practical inquiry should include:
- grade name: SUS304, AISI 304, ASTM A276 304, EN 1.4301 or another accepted wording
- shape: round bar, hex bar, square bar or flat bar
- size: diameter, across-flats size, side length, thickness or width
- tolerance: h9, h10, h11, ASTM tolerance or drawing tolerance
- finish: hot rolled, cold drawn, peeled, polished or centerless ground
- standard: ASTM A276, JIS G4303, GB/T 1220, EN 10088-3 or buyer drawing
- documents: MTC, heat number, labels, packing list and any required inspection record
- destination: country, port and packing requirement
For example, 304 stainless steel round bar can mean many things. A 12 mm cold drawn h9 bar for CNC feeding is not the same supply route as a 60 mm hot rolled bar for general fabrication.
Example Inquiry Wording
A vague inquiry creates slow replies. A clear inquiry is much easier to quote.
Weak inquiry:
> Need SUS304 bar. Please quote.
Better inquiry:
> 304 stainless steel round bar, ASTM A276 / SUS304 equivalent acceptable, diameter 20 mm, length 3 m, peeled surface, MTC required, 500 kg trial order, destination Vietnam.
The second version tells the supplier what to check. It also gives room to confirm whether SUS304, AISI 304 or ASTM A276 304 wording is acceptable for the buyer's documents.
Where ASTM A276 Fits In
Many international bar buyers use ASTM A276 304 stainless steel bar as the order language. ASTM A276 is commonly used for stainless steel bars and shapes, so it is a useful reference when the product is a round, square, hex or flat bar.
This does not mean every 304 bar automatically meets every project requirement. Product form, condition, testing, size range and document wording still need a real stock and document review.
If your project compares ASTM A276 with pressure-related wording such as ASTM A479 or ASME SA479, read our ASTM A276 vs ASME SA479 stainless steel bar guide before confirming the PO.
Southeast Asia Buyer Note
In Southeast Asia, especially in Japanese-invested factories, SUS304 is very common on drawings, maintenance lists and internal approval documents. A sourcing email may say SUS304, while the supplier's stock list says 304 or AISI 304.
That is normal. The important step is to align the documents before shipment.
For Vietnam, Thailand, Malaysia, Singapore and Indonesia buyers, check whether the final MTC, packing list and invoice need the same grade wording as the purchase order. If one document says SUS304 and another says 304, it may still be technically acceptable, but some end users want exact naming consistency.
Practical MTC Checks for SUS304 and AISI 304
The MTC should help the buyer connect the supplied bar to the required grade.
For a 304 bar order, check these points:
| MTC Item | Why It Matters |
|---|---|
| Grade wording | Confirms whether the certificate shows 304, SUS304, S30400 or another accepted name |
| Heat number | Connects the MTC to the actual batch and labels |
| Chemical composition | Helps verify the 304 family chemistry shown by the certificate |
| Standard reference | Shows the standard basis used for the supplied material |
| Product description | Should match bar form, size and condition as far as the document allows |
| Supplier and batch details | Helps reduce document mismatch during import or internal QA review |
If you are not sure how to read the certificate, use our stainless steel MTC guide before approving the shipment.
When 304 Is Not the Only Question
Sometimes the buyer asks about SUS304 vs AISI 304, but the real issue is different.
If the part will be welded, compare 304 vs 304L first. Low carbon wording may matter more than whether the document says SUS or AISI. Our 304 vs 304L stainless steel bar guide explains when 304L is worth reviewing.
If the part will be used near salt spray or chloride exposure, compare 304 vs 316. Grade naming will not solve a corrosion mismatch. For that decision path, read our 304 vs 316 stainless steel guide for Southeast Asia projects.
If you only need the naming map, use the stainless steel grade equivalent lookup for 304, SUS304, 1.4301 and UNS references.
How FX Stainless Steel Reviews This Type of Inquiry
When we receive a SUS304 round bar or AISI 304 stainless steel bar inquiry, we first keep the buyer's original grade wording visible. If the drawing says SUS304, the purchase order says AISI 304 and the buyer also mentions EN 1.4301, those names should be reviewed together before quotation.
Our review usually starts with these checks:
- original grade wording: SUS304, AISI 304, 304, EN 1.4301, UNS S30400 or GB/T 1220 06Cr19Ni10
- requested standard: ASTM A276, JIS G4303, EN 10088-3, GB/T 1220 or buyer drawing
- stock batch condition, heat number and available MTC wording
- bar shape, diameter or across-flats size, finish, tolerance and cutting plan
- whether 304L or dual-certified wording is needed for welding or document approval
- packing labels, invoice, packing list and MTC wording consistency before shipment
- destination port and export document requirements
If the exact wording cannot be confirmed from current stock, the supply route can be reviewed before quotation. The important point is to resolve grade naming and certificate wording before shipment, not after the material arrives at the buyer's warehouse.
Buyer Checklist Before Ordering
Use this checklist before confirming a 304 stainless steel bar order.
| Question | Buyer Action |
|---|---|
| Does the drawing say SUS304, AISI 304 or another name? | Keep the original wording visible in the inquiry |
| Is an exact standard required? | State ASTM A276, JIS G4303, GB/T 1220, EN 10088-3 or drawing requirement |
| Is 304L needed? | Check welding, low-carbon wording and end-user approval |
| Is the bar shape clear? | Confirm round, hex, square, flat, peeled, ground or cut piece |
| Is the MTC requirement clear? | Ask for grade wording, heat number and standard reference before shipment |
| Does the end user accept equivalent wording? | Confirm before cargo release, not after arrival |
Conclusion
SUS304 and AISI 304 usually refer to the same 304 stainless steel grade family, but a good purchase order should not rely on grade name alone.
For stainless steel bar buying, the workable order comes from the standard, bar shape, size, finish, tolerance, MTC wording and destination, not from the grade name alone.
Sources
Useful public references for this topic include ASTM A276/A276M stainless steel bars and shapes, EN 10088-3 stainless steel bars, rods, wire, sections and bright products, JIS G 4303 stainless steel bars and GB/T 1220 stainless steel bars.
Frequently Asked Questions (FAQ)
Q. Is SUS304 the same as AISI 304?
A. In many practical buying situations, yes. SUS304 and AISI 304 usually refer to the same 304 austenitic stainless steel grade family. The final order should still confirm the standard, product form and MTC wording.
Q. Is SUS304 the same as ASTM A276 304 stainless steel bar?
A. Not exactly as a phrase. SUS304 is a JIS grade name. ASTM A276 304 stainless steel bar is common ASTM order wording for stainless steel bars and shapes. They may be equivalent in grade family, but the PO should state what the buyer accepts.
Q. Is EN 1.4301 equivalent to 304 stainless steel?
A. EN 1.4301 is commonly treated as the European equivalent of 304 stainless steel. Buyers should still confirm the drawing, MTC, chemistry and any mechanical or project-specific requirement.
Q. Can I write only SUS304 on my purchase order?
A. You can if the drawing or end user uses that wording. For smoother quotation, add the standard, bar shape, size, finish, tolerance, MTC requirement, quantity and destination port.
Q. What should the MTC show for 304 stainless steel bar?
A. The MTC should show grade wording, heat number, chemical composition, standard reference and product information. It should match the labels, packing list and purchase order.
CTA
Send your grade name, accepted standard, bar shape, size, surface finish, tolerance, quantity, MTC requirement and destination port through our stainless steel bar quote page. FX Stainless Steel can help review whether 304 stainless steel bar, 304 stainless steel round bar or another supply route fits your order.