Steel grade equivalents: SAE, DIN and EN

November 3, 2026  ·  Indumor

The drawing lands on the bench with the usual line in the title block: "Material: SAE 4140 steel, quenched and tempered". A 60 mm shaft, 900 mm long, nothing unusual. But the steel merchant has no 4140 in that size for a month and offers a European 42CrMo4 bar with a heat certificate instead. Does it do the job? It does, and the "almost" that separates the two names is what you need to understand to buy without surprises.

An Argentine drawing calls out steel by SAE or AISI number, the way trade schools teach it and bar stockists sell it: 1010, 1045, 4140, 8620. Structural grades go by IRAM-IAS U 500-503 (F-24, F-36) or by ASTM (A36). The certificate, on the other hand, carries whatever name the mill of origin uses: EN, ASTM or JIS. The same steel travels the world under four names.

How to read each name

SAE/AISI uses four digits (five for bearing steels): the first two give the family and the last two the carbon in hundredths of a percent. A 1045 is a plain carbon steel with 0.45 % C; an 8620 is a nickel-chromium-molybdenum steel with 0.20 %. A letter in the middle flags an addition: the L in 12L14 is lead, the B in 15B21 is boron. The American UNS number (G41400) and the Japanese JIS name (SCM440) usually carry that same number inside.

The European name (EN 10027-1) describes the composition. Unalloyed grades take a C and the carbon in hundredths: C45E. Low-alloy grades start with the carbon, continue with the alloying elements in order of content, and the final figure is divided by the element's factor: 4 for chromium, manganese, nickel and silicon, 10 for molybdenum and vanadium, 100 for sulfur. So 42CrMo4 has 0.42 % carbon and 4 ÷ 4 = 1 % chromium; molybdenum gets no figure because there is little of it. When any element exceeds 5 %, the name starts with X and the figures are direct: X5CrNi18-10 is 304. Next to the name goes the material number (EN 10027-2), a one, a point and four digits, which is what the certificate usually shows.

What "equivalent" means, and what it does not

Equivalent means a similar composition, not an identical one. 4140 and 42CrMo4 share their chromium and molybdenum, but the European grade allows up to 0.45 % carbon and 1.20 % chromium and caps phosphorus and sulfur more tightly. The differences that are not in the composition weigh more: the delivery condition (+A annealed, +N normalized, +QT quenched and tempered), the bar tolerance (EN 10060 or ASTM A29) and guaranteed hardenability (the +H suffix in EN, the H-bands of SAE J1268).

When the exact grade is not available, the rule is to stay in the same family at the same carbon, or slightly higher. A 1045 in place of a 4140 changes the hardenability: in a 60 mm bar the 1045 will not harden through to the core. Treatment temperatures are in chapter 20; what each certificate type guarantees is in the guide to EN 10204 certificates.

Carbon and free-cutting steels

These are the ones bought most. From 1010 to 1020 they carburize and weld without trouble; from 1035 up they harden, and 1045 is the general-purpose shaft steel of any shop. The 12xx grades and 12L14 are made for the screw machine: sulfur and lead break the chip, but they neither weld well nor harden.

Find a steel

Two names with a slash: variants of the same steel (with or without capped sulfur, or strip and bar). 1141 has no exact EN match: 44SMn28 pairs with 1144.

Alloy steels

Chromium, molybdenum and nickel are there to harden deeper and stay tough after tempering, not to raise the maximum hardness. A 4140 and a 1045 reach the same surface hardness; in a thick bar only the 4140 keeps it through to the center. 8620 is the carburizing steel for gears and 52100 the bearing steel.

Find an alloy steel

Compositions are the SAE ranges; EN and JIS differ by hundredths. Q&T = quenched and tempered. 40NiCrMo2-2 is not in EN 10083-3; ISO 683-2 has 41CrNiMo2 (1.6584).

Tool steels

The AISI letter tells you how it is quenched: W in water, O in oil, A in air, D for high chromium, H for hot work, S for shock, M for molybdenum high-speed, P for plastic molds. ISO 4957 names them by composition; the table gives nominal values, and the real analysis comes with the heat.

Nominal compositions (middle of the range); for S1, L6 and P20 they are those of the EN steel, which differ somewhat from AISI. S1 and S7 are approximate pairs: S7 is sold as 1.2355 or 1.2357, depending on the mill. Temperatures and hardness: chapter 20.

Structural steels and sheet: what IRAM calls them

For structural grades the name gives strength, not composition. S235JR has a minimum yield of 235 MPa and 27 J Charpy at 20 °C; A36 has 36 ksi (250 MPa); the Argentine F-24, 24 kgf/mm² (235 MPa). All three serve an ordinary structure. Minimum yield drops with thickness; the table gives the value for plate up to 16 mm.

Re = yield strength, Rm = tensile strength. The IRAM name carries the yield in kgf/mm². F-24 and F-26 per the CIRSOC 301 worked examples (F-26 drops to 245 MPa in a 25 mm bar); F-20, F-22 and F-36 are guide values: check them against the standard.

Stainless, cast irons and non-ferrous

304 and 316 are austenitic and do not harden; 410 and 420 are martensitic and do; 430 is ferritic and stays as supplied. The L versions keep carbon under 0.03 % so they can be welded without chromium carbides precipitating; which one to choose is covered in the guide 304 vs 316.

Cast iron names carry the tensile strength in MPa: GJL-250 is a gray iron of 250 MPa and GJS-500-7 a ductile iron of 500 MPa with 7 % elongation; ASTM A48 classes are in ksi. Aluminum alloy numbers are the same everywhere and what changes is the temper: a 6061-T6 has about two and a half times the strength of a 6061-O. For bronzes the shop name rules: "SAE 660 bronze" is C93200.

Gray iron has no defined yield. ASTM A48 classes are in ksi: class 35 = 241 MPa. A536 grades do not line up exactly with EN grades: the pairing is approximate.

O = annealed, H = strain hardened, T4 = naturally aged, T6 = artificially aged. Rm is a guide value.

One habit that saves arguments: when the material arrives under a different name, write that name and the certificate number next to the material callout on the drawing. The next time the part comes back to the shop, nobody has to work this out again.

Frequently asked questions

What is the European equivalent of SAE 1045?

C45E (material number 1.1191), or C45 (1.0503) when capped sulfur is not required. In old DIN it was Ck 45; in JIS, S45C. All carry 0.42 to 0.50 % carbon.

Are 4140 and 42CrMo4 the same steel?

They are equivalent, not identical: the same chromium and molybdenum, but 42CrMo4 allows slightly more carbon and chromium and caps phosphorus and sulfur more tightly. For a quenched and tempered shaft they are used interchangeably; check the composition on the heat certificate.

What is IRAM F-24 steel?

The everyday structural grade of the Argentine standard IRAM-IAS U 500-503: 24 kgf/mm² (235 MPa) minimum yield. Broadly equivalent to European S235JR and to ASTM A36.

Sources: EN 10027-1:2016 and EN 10027-2:2015 (designation); EN 10083-1/-2/-3 (steels for quenching and tempering); EN 10084 (case hardening); EN 10087 (free-cutting), these three now replaced by EN ISO 683; EN 10089 (spring steels); ISO 683-17 (bearing steels); EN 10088-1 (stainless); EN 10025-2 and EN 10028-2 (structural and pressure vessel steels); EN 10111 and EN 10130 (sheet); ISO 4957 (tool steels); SAE J403, SAE J404 and SAE J1086 (UNS); SAE J1268 (H-bands); ASTM A36, A572, A283, A516, A29, A48, A536; IRAM-IAS U 500-503; JIS G4051, G4053, G4303, G4401, G4403, G4404, G4801, G4804, G4805, G5501 and G5502; EN 1561 and EN 1563 (cast irons); EN 573-3 (aluminum); EN 1652 and EN 1982 (copper alloys).