Steel grade equivalents: EN, GOST, AISI and PN
Material arrives with an EN certificate, the drawing was made to GOST, and the stainless in the rack is known by its AISI number. The table below lines the four systems up — with the caveat that makes it safe to use.
Matching strength does not mean matching composition, and welding depends on composition. Two grades with the same yield strength can have different carbon equivalents and need different preheat. Use the table to work out what you are holding; use the certificate of the actual batch to choose parameters and filler.
How an EN designation reads
Structural steels: the letter S, the minimum yield strength in MPa, then the impact grade. So S275JR is 275 MPa with 27 J at room temperature. Quality steels start with C and the carbon content in hundredths of a per cent: C45 is 0.45 % C. Alloy steels spell out the alloying elements with their content multiplied by a factor: 42CrMo4 is 0.42 % C with about 1 % chromium and molybdenum.
Stainless steels are usually quoted by material number — 1.4301, 1.4404, 1.4462 — because the name designation is long. The number is unambiguous, which is why it belongs on the order.
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Structural steels
| EN | Material no. | GOST | AISI / ASTM | PN (old) | Weldability |
|---|---|---|---|---|---|
| S185 | 1.0035 | Ст0 | — | St0S | good, no preheat |
| S235JR | 1.0038 | Ст3сп, Ст3пс | A283 Gr. C | St3S | good, no preheat |
| S235J2 | 1.0117 | Ст3сп5 | — | St3SX | good, no preheat |
| S275JR | 1.0044 | Ст4сп | A570 Gr. 40 | St4S | good, no preheat |
| S355J2 | 1.0577 | 09Г2С, 17Г1С | A572 Gr. 50 | 18G2A | good, preheat from about 30 mm |
| E295 | 1.0050 | Ст5пс | — | St5 | limited, preheat usually needed |
| E335 | 1.0060 | Ст6пс | — | St6 | limited, preheat usually needed |
Quality and alloy steels
| EN | Material no. | GOST | AISI / ASTM | PN (old) | Weldability |
|---|---|---|---|---|---|
| C22 | 1.0402 | Сталь 20 | 1020 | — | good, no preheat |
| C35 | 1.0501 | Сталь 35 | 1035 | — | limited, preheat usually needed |
| C45 | 1.0503 | Сталь 45 | 1045 | — | limited, preheat usually needed |
| 16Mo3 | 1.5415 | 16М | A204 Gr. A | — | preheat and heat treatment |
| 25CrMo4 | 1.7218 | 25ХМ | 4130 | — | preheat and heat treatment |
| 42CrMo4 | 1.7225 | 38ХМ | 4140 | — | preheat and heat treatment |
| 34CrNiMo6 | 1.6582 | 34ХН3М | 4340 | — | preheat and heat treatment |
Stainless steels
| EN | Material no. | GOST | AISI / ASTM | PN (old) | Weldability |
|---|---|---|---|---|---|
| X5CrNi18-10 | 1.4301 | 08Х18Н10 | 304 | — | good, keep heat input low |
| X2CrNi19-11 | 1.4306 | 03Х18Н11 | 304L | — | good, keep heat input low |
| X5CrNiMo17-12-2 | 1.4401 | 10Х17Н13М2 | 316 | — | good, keep heat input low |
| X2CrNiMo17-12-2 | 1.4404 | 03Х17Н14М2 | 316L | — | good, keep heat input low |
| X6CrNiTi18-10 | 1.4541 | 12Х18Н10Т | 321 | — | good, keep heat input low |
| X6Cr17 | 1.4016 | 12Х17 | 430 | — | limited, grain growth |
| X2CrNiN23-4 | 1.4362 | — | 2304 (duplex) | — | good, with interpass control |
| X2CrNiMoN22-5-3 | 1.4462 | — | 2205 (duplex) | — | good, with interpass control |
What this means for welding
The weldability column is a first orientation only. Run the composition from the certificate through the carbon equivalent calculator and, if it comes out above 0.40 %, through the preheat calculator as well. For austenitic stainless the risk is the opposite one: not hardening but sensitisation and distortion, which is why the advice there is to keep the heat input down — see welding stainless steel.
Frequently asked questions
What does S355J2 mean?
S is structural steel, 355 is the minimum yield strength in MPa, and J2 is an impact energy of 27 J tested at −20 °C. JR is tested at +20 °C, J0 at 0 °C, and K2 requires 40 J at −20 °C.
Is 1.4301 the same as AISI 304?
In composition, near enough: 1.4301 is the EN material number, X5CrNi18-10 is its name designation and AISI 304 is the American equivalent. The tolerances on carbon and nitrogen can differ, so for anything that matters you check the certificate rather than the table.
Can I substitute one equivalent for another?
Not on your own authority. An equivalent matches strength, not chemistry, and welding cares about chemistry. Substitution is a decision for the designer, recorded on the drawing — with the certificate of the actual batch in hand.
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