How to Convert ASTM, EN, DIN and JIS Stainless Steel Grades

Introduction

To convert ASTM, EN, DIN and JIS stainless steel grades, buyers should compare the material designation, chemical composition, product standard, mechanical properties, heat treatment condition, delivery form and certificate data instead of relying only on a simple grade name. A grade such as 304, 1.4301, X5CrNi18-10 and SUS304 may look equivalent in many commercial orders, but the final acceptance should always be based on the purchase order, applicable standard and EN 10204 3.1 material certificate.

Stainless steel grade conversion is important for international purchasing teams, engineering companies, fabricators and importers who receive drawings or inquiries using different standard systems. ASTM and AISI designations are common in North America and global trade, EN and DIN designations are widely used in Europe, and JIS designations are common in Japan and many Asian markets. This guide explains standard scope, grade list, certificate checklist, common buyer mistakes, FAQ and how to request a downloadable stainless steel grade cross-reference sheet.

Standard Scope: ASTM, EN, DIN and JIS

Different standard systems may describe stainless steel in different ways. Some names refer to material grade, while others refer to product forms such as plate, pipe, bar, wire or fittings. Buyers should identify the correct scope before converting grades.

Standard System	Common Example	Main Use in Stainless Steel Purchasing
ASTM / AISI / UNS	304, 316L, UNS S30403, ASTM A240, ASTM A312	Common for plate, sheet, pipe, tube, bar, wire, fittings and global export orders.
EN	1.4301, 1.4404, X5CrNi18-10, X2CrNiMo17-12-2	Used for European projects, engineering drawings, pressure equipment and material certificates.
DIN	1.4301, 1.4571, X6CrNiTi18-10	Older German designations still appear in drawings, maintenance lists and buyer RFQs.
JIS	SUS304, SUS316L, SUS430, SUS329J3L	Common for Japanese and Asian industrial, food, chemical and machinery applications.
Customer Drawing	“304L or equivalent”, “EN 1.4404”, “SUS316L”	The drawing or purchase specification controls final acceptance and substitution approval.

Common Stainless Steel Grade Conversion List

The following table gives practical approximate equivalents for common stainless steel grades. These names are widely used in commercial trade, but buyers should still verify the exact chemical and mechanical requirements in the applicable standard.

Common Grade	UNS	EN / DIN	JIS	Typical Use
304	S30400	1.4301 / X5CrNi18-10	SUS304	General corrosion-resistant sheet, plate, pipe, bar and fabricated parts.
304L	S30403	1.4307 / X2CrNi18-9	SUS304L	Welded piping, tanks, food equipment and chemical lines requiring low carbon.
316	S31600	1.4401 / X5CrNiMo17-12-2	SUS316	Chemical, marine, food and chloride-containing environments.
316L	S31603	1.4404 / X2CrNiMo17-12-2	SUS316L	Welded chemical, marine, sanitary and pressure-related equipment.
321	S32100	1.4541 / X6CrNiTi18-10	SUS321	Stabilized stainless steel for selected high-temperature and welded service.
347	S34700	1.4550 / X6CrNiNb18-10	SUS347	High-temperature welded parts, refinery equipment and heat-resistant fabrications.
310S	S31008	1.4845 / X8CrNi25-21	SUS310S	Furnace parts, heat treatment equipment and high-temperature oxidation service.
430	S43000	1.4016 / X6Cr17	SUS430	Decorative parts, kitchenware, appliances and magnetic ferritic stainless applications.
410	S41000	1.4006 / X12Cr13	SUS410	Martensitic stainless steel for shafts, valve parts, pump parts and wear-related components.
2205 Duplex	S32205 / S31803	1.4462 / X2CrNiMoN22-5-3	SUS329J3L	Duplex stainless steel for chloride service, pressure equipment and offshore applications.
904L	N08904	1.4539 / X1NiCrMoCu25-20-5	SUS890L	Acid service, chloride-containing environments and high-corrosion chemical equipment.

Why Grade Conversion Is Not Always One-to-One

Many stainless steel grades have approximate equivalents, but they are not always fully interchangeable. Different standards may have small differences in chemical limits, mechanical property requirements, product form tolerances, heat treatment, testing methods and certificate wording.

Risk Area	What Can Be Different	Buyer Action
Chemical Composition	Carbon, chromium, nickel, molybdenum, nitrogen, copper and stabilizing elements	Compare actual MTC values with the required standard limits.
Mechanical Properties	Tensile strength, yield strength, elongation, hardness and impact requirements	Check whether the product form and standard require different property values.
Product Standard	Plate, pipe, bar, wire, fittings and fasteners may follow different standards	Specify both grade and product standard in the purchase order.
Delivery Condition	Annealed, solution treated, cold drawn, quenched, tempered, polished or pickled	Confirm condition and surface finish before accepting equivalence.
Testing Requirement	PMI, UT, PT, RT, intergranular corrosion test, impact test or pressure test	Add all required tests to the RFQ and PO, not only the grade name.

Certificate Checklist for Grade Conversion

When a stainless steel grade is converted from ASTM to EN, DIN or JIS, the material certificate becomes the key document for verification. Buyers should review every important field before approving shipment or receiving the goods.

Certificate Item	What to Check	Why It Matters
Certificate Type	EN 10204 3.1, 3.2 or customer-required inspection certificate	Confirms whether the certificate level matches the purchase order.
Material Grade	304L, UNS S30403, 1.4307, SUS304L or other required designation	Prevents wrong grade or wrong equivalent from being shipped.
Heat Number	Heat/lot number on MTC, product labels, packing list and product marking	Ensures traceability from material to certificate.
Chemical Composition	C, Cr, Ni, Mo, Mn, Si, P, S, N and special elements such as Ti, Nb or Cu	Chemical limits are the most important basis for grade verification.
Mechanical Properties	Tensile strength, yield strength, elongation, hardness and impact test if required	Confirms whether the material meets the standard and project requirement.
Product Standard	ASTM A240, ASTM A312, ASTM A276, EN 10088, JIS G4304 or other product standard	Grade equivalence does not replace correct product standard compliance.
Dimensions and Quantity	Thickness, OD, wall, diameter, width, length, tolerance and weight	Confirms the shipment matches the PO and packing list.

Specification Checks Before Approving an Equivalent Grade

Before approving a converted grade, buyers should review the application and service environment. A grade that is acceptable for decorative parts may not be acceptable for pressure equipment, chemical lines or welded structures.

✅ Confirm the original grade and required equivalent grade, such as 316L / 1.4404 / SUS316L.

✅ Confirm the product form: plate, sheet, pipe, tube, bar, wire, strip, fitting, flange or fastener.

✅ Check chemical composition against the required standard, not only the grade name.

✅ Check mechanical properties, heat treatment, delivery condition and surface finish.

✅ Confirm corrosion environment, temperature, pressure, welding and fabrication method.

✅ Verify MTC, heat number, label, packing list and product marking are consistent.

✅ Add PMI, UT, PT, RT, IGC, impact test or third-party inspection when project requires it.

✅ Get written approval before substituting one standard designation for another in controlled projects.

Buyer Mistakes to Avoid

Assuming all equivalent grades are identical: Approximate equivalence does not guarantee identical chemistry, mechanical properties, testing or product standard requirements.

Confusing grade and product standard: 316L is a grade, while ASTM A312 or ASTM A240 is a product standard. Buyers should specify both.

Replacing 316L with 316: Low-carbon grades are often selected for welded parts. Substitution can affect corrosion performance after welding.

Ignoring stabilizing elements: 321 contains titanium stabilization, while 347 contains niobium stabilization. They are not the same as 304 or 304L in every application.

Not checking molybdenum: 304 and 316 are not equivalent. 316 contains molybdenum and is often selected for better chloride resistance.

Accepting certificates without heat-number matching: MTC, product labels, packing list and physical marking should match the same heat number.

Using old DIN names without clarification: Some drawings use old DIN names. Buyers should confirm the current EN material number and actual standard requirement.

FAQ

How do I convert ASTM, EN, DIN and JIS stainless steel grades?

Start by matching the common grade name, UNS number, EN material number and JIS designation. Then verify chemical composition, mechanical properties, product standard, delivery condition and certificate data before approving the equivalent grade.

Is ASTM 304 the same as EN 1.4301 and JIS SUS304?

ASTM 304, EN 1.4301 and JIS SUS304 are commonly treated as commercial equivalents for many applications. However, buyers should still check the specific product standard, chemical composition and mechanical requirements on the MTC.

Is 316L the same as 1.4404 and SUS316L?

316L, EN 1.4404 and SUS316L are commonly used as equivalent low-carbon molybdenum-bearing stainless steel grades. Final acceptance should be based on the required standard, chemistry, mechanical properties and certificate.

Can I replace 304 with 304L?

304L can often be used where 304 is required, especially for welded applications, but substitution should be approved if the project has specific mechanical strength, code or end-user requirements.

Can I replace 304 with 316L?

316L generally offers better chloride corrosion resistance than 304, but it is not automatically a direct substitute in every project. The drawing, cost, standard, mechanical requirements and end-user approval should be checked.

What certificate is needed for stainless steel grade verification?

EN 10204 3.1 MTC is commonly requested for stainless steel grade verification. It should show grade, heat number, chemical composition, mechanical properties, product standard, size and manufacturer inspection information.

Why can two equivalent grades have different requirements?

Different standard systems may use different chemical limits, product testing rules, tolerance requirements and delivery conditions. That is why buyers should verify actual certificate data instead of relying only on grade-name conversion.

Downloadable Spec CTA

Related Stainless Steel Products

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