09G2S steel: properties, composition, equivalents

09G2S is the CIS low-alloy structural steel of GOST 19281: 345 MPa yield to 10 mm, 490 MPa minimum tensile, with guaranteed toughness down to −70 °C.

Last updated 26 September 2026

What is 09G2S?

09G2S is the low-alloy structural steel that does in the CIS what S355 does in Europe — and it does one thing better. Defined in GOST 19281, it delivers 345 MPa yield with only 0.12 % carbon, buying its strength from 1.3–1.7 % manganese and 0.5–0.8 % silicon instead. The consequence is a steel that is strong, tough at very low temperature and unusually forgiving to weld.

The designation is literally the recipe: 09 is the nominal carbon in hundredths of a per cent, Г is the Cyrillic letter for manganese (*marganets*), 2 is roughly its percentage, and С is silicon (*kremniy*, written with S in the Russian alloy code). Anyone who can read that pattern can read most GOST alloy names.

The feature that sells it is the cold. Depending on the category ordered, 09G2S is impact-tested at −40 °C, −60 °C or −70 °C, and after mechanical ageing as well. That is the reason it dominates structures in Siberia, Kazakhstan and the Russian north, and the reason it turns up in export enquiries for cold-climate projects where a European J2 grade would be the obvious alternative.

Against S355J2 the substitution works on strength and needs care on the test. 09G2S is 345 MPa against 355 at the first step — a 3 % difference that a design check will usually absorb — but GOST states impact energy as KCU in J/cm² on a U-notch while EN states KV in joules on a V-notch. The U-notch test is the gentler of the two and the numbers do not convert. Where the design depends on toughness, the V-notch test has to be ordered explicitly.

09G2S chemical composition

GOST 19281-2014 ladle analysis. The name is the composition read aloud: **09** is 0.09 % carbon nominal, **Г** (G) is manganese, **2** is roughly 2 % of it, and **С** (S) is silicon. Low carbon with high manganese and silicon is a classic solid-solution strengthening recipe — the strength comes from the alloy, not from carbon, which is why the grade welds far better than its yield would suggest.

09G2S mechanical properties

Strength class 325 or 345 depending on the product and thickness; GOST 19281 organises the grades by strength class rather than by name, so a certificate may read "09G2S, class 345". Elongation is 21 % across the range. Unlike GOST 380, this standard carries its own mechanical table — 09G2S is a complete specification in one document.

Impact toughness

09G2S requires a minimum Charpy V-notch energy of 29 J at -70 °C (KCU 29 J/cm² at −70 °C, category dependent; also tested after mechanical ageing). Low-temperature toughness is the whole point of the grade. Depending on the category ordered, 09G2S is impact-tested at **−40 °C, −60 °C or −70 °C**, and additionally after mechanical ageing. GOST states the requirement as KCU in J/cm² on a U-notch specimen, which is a less severe test than the European V-notch KV — the two figures are not interchangeable, and a design written to EN should ask for an ISO 148 V-notch test as a supplementary requirement.

09G2S equivalent grades

Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for 09G2S →

Old and superseded designations

Product forms and tolerance standards

Product forms: heavy plate to GOST 19281 and GOST 5520 (boiler and vessel duty), hot-rolled sections: I beam, channel, angle, hot-rolled coil and strip, seamless pipe to GOST 8731 / 8732 and welded pipe to GOST 10706, round and flat bar.

Dimensional tolerances: heavy plate: GOST 19903; thin sheet and coil: GOST 19903 / 19904; I beam: GOST 8239, wide-flange GOST 26020; seamless pipe: GOST 8732.

Key property values

09G2S yield strength

345 MPa minimum up to 10 mm, then 325 MPa to 20 mm, 305 MPa to 32 mm, 285 MPa to 60 mm, 275 MPa to 80 mm and 265 MPa to 160 mm. The steps are closer together than in EN 10025-2, where S355 holds 345 MPa all the way to 40 mm — so in the 10–40 mm band the European grade is nominally the stronger of the two.

09G2S tensile strength

490 MPa minimum up to 32 mm, falling to 470, 460, 450, 440 and 430 MPa through the thickness bands. GOST sets a floor with no ceiling, where EN 10025-2 gives S355 a 470–630 MPa band. A 09G2S plate can therefore be stronger at the top end than any conforming S355 plate.

09G2S chemical composition

C ≤ 0.12 %, Si 0.50–0.80 %, Mn 1.30–1.70 %, P ≤ 0.035 %, S ≤ 0.040 %, N ≤ 0.008 %, with Cr, Ni and Cu each ≤ 0.30 % as residuals. The carbon equivalent works out around 0.37–0.42, comparable with S355J2 and low enough that preheat is rarely needed below 30 mm.

Low-temperature toughness

This is the grade's reason for existing. Categories in GOST 19281 set the impact temperature at −40 °C, −60 °C or −70 °C, with a further requirement after mechanical ageing. Few commodity structural steels anywhere are routinely certified at −70 °C, and the fine grain produced by the manganese-silicon chemistry is what makes it possible at this carbon level.

The GOST 19281 family

09G2S sits in a family organised by strength class from 265 to 590 MPa. 09G2 is the same steel without silicon and one class lower. 17G1S is the higher-carbon, higher-strength member used for pipe. 10KhSND and 15KhSND add chromium, nickel and copper for atmospheric corrosion resistance — the CIS weathering steels, comparable with S355J2W.

Accepting 09G2S against S355J2

Four checks. Yield at the governing thickness, since the ladders step differently between 10 and 40 mm. The impact test: temperature, category and whether a V-notch result is available. The tensile ceiling, because GOST sets none and a weld procedure written for a capped band may not cover the material. And the delivery condition — GOST 19281 allows as-rolled, normalised and controlled-rolled, and the certificate should say which.

Weldability

09G2S is one of the more forgiving high-strength structural steels to weld, and that is a direct consequence of its chemistry: at 0.12 % carbon maximum, the hardenability that produces cold cracking simply is not there. Carbon equivalent typically runs 0.37–0.42, so preheat is normally unnecessary below about 30 mm at ordinary ambient temperature, and 100–150 °C is enough above it. All arc processes apply. CIS practice uses UONI-13/55 electrodes and Sv-08G2S wire — the latter being the near-identical filler composition, which is why it is also the standard consumable for welding ordinary carbon steel throughout the region. For joints that must hold the low-temperature guarantee, match the consumable's certified impact temperature to the plate's, not to the room's.

Machining, forming and heat treatment

Machinability is moderate and noticeably tougher than St3sp: the manganese and silicon that provide the strength also make the steel gummy and raise cutting forces by roughly a quarter over a plain carbon steel of the same hardness. Sharp tooling, positive rake and adequate feed are the usual answers. Cold forming is good for the strength class — elongation is 21 % across the whole thickness range — and the grade bends and rolls well, but spring-back is higher than on a 235 MPa steel and the absence of a tensile ceiling means it varies between heats.

Typical applications

• Structural steelwork for cold climates: Siberia, the Russian north, Kazakhstan, Mongolia
• Bridges, gantries, crane runways and heavy welded frames
• Tank, silo and pressure-vessel shells (with GOST 5520 for vessel duty)
• Oil and gas structures, pipe racks and offshore module steelwork
• Railway wagon and heavy vehicle structures
• Seamless and welded pipe for structural and low-temperature service

Frequently asked questions

Related grades

Verified against GOST 19281-2014; GOST 19281-2014 — Rolled steel with increased strength. General specifications; GOST 5520-2017 — Plate for boilers and pressure vessels, for the vessel-duty variant. Last checked: September 2026.