Plate 09G2S

09G2S is a low-alloy structural steel of increased strength to GOST 19281-2014: carbon up to 0.12 %, manganese 1.3–1.7 %, silicon 0.5–0.8 % to GOST 19281. The plate is hot-rolled to the dimensions of GOST 19903-2015: thin sheet from coil cut to length, heavy plate on reversing mills from a slab. Manganese and silicon give a strength above that of St3 while weldability is retained, so 09G2S is used where the weight of a structure has to be reduced or service in frost has to be ensured.

The strength class to GOST 19281 depends on thickness and is stated in the certificate. The steel category sets the impact test conditions: category 12 — at −40 °C, category 15 — at −70 °C; for structures in Uzbekistan category 12 is usually sufficient, cryogenic and northern equipment calls for 15. The Chinese equivalent is Q355B to GB/T 1591-2018 (Q345B before 2018) with a yield strength of 355 MPa minimum and an impact test at +20 °C; the European one is S355JR, S355J2 to EN 10025-2, the American one A572 Grade 50. These are the nearest equivalents by strength, not identity: if the project specifies a 09G2S category for impact toughness, we agree with the mill rolling and testing to GOST and a corresponding entry in the certificate.

At the mill before shipment the bureau's inspector measures thickness with a micrometer at several points of the sample sheets and checks it against the tolerance of the standard, checks width, length and flatness, and examines the surface for laminations, laps and delamination along the cut edge. The mill test certificate (MTC) is checked against the tag and marking by heat number; in the composition the manganese and silicon content is checked against the limits of GOST 19281, in the mechanical properties — yield strength, tensile strength, elongation and impact toughness at the temperature set by the category. The report with photographs is handed to you before shipment.