Structural Steel Grades: С245, С345, 09Г2С — Yield and Tensile Strength

What the designation С245, С345 means

A grade consists of the letter С and a number. The number equals the minimum yield strength in N/mm² for the thinnest rolled product of that grade: 245 for С245, 345 for С345. The larger the number, the stronger the steel. The minimum values fall with thickness, as the tables below show.

Former designations, such as Ст3пс5 or 09Г2С, are still found in drawings and price lists. The first table shows how the new grades correspond to the old ones.

Steel grades and former designations · ГОСТ 27772-88 (former; current DSTU 8539:2015)

The “Steel standard” column is the standard for the former designation. A dash marks a standard not given in the text.

Shapes: I-beams, channels, angles

For sections the minimum mechanical properties are set by flange thickness. For grade С345 up to 10 mm the yield strength is at least 345 N/mm² and the tensile strength 490 N/mm²; for a flange over 10 to 20 mm they are 325 and 470, and over 20 to 40 mm 305 and 460.

Shapes: minimum mechanical properties by flange thickness · ГОСТ 27772-88 (former; current DSTU 8539:2015)

σy is the minimum yield strength, σu the minimum tensile strength, δ5 the minimum elongation, bend is the mandrel diameter d, a the specimen thickness. The values are minimums, not actual figures.

Sheet and plate

For sheet the thickness range is wider: from 2 mm, and for grade С345 up to 160 mm. The yield strength of С345 falls from 345 N/mm² for sheet up to 10 mm to 265 N/mm² for sheet 80 to 160 mm thick.

Sheet and plate: minimum mechanical properties by thickness · ГОСТ 27772-88 (former; current DSTU 8539:2015)

The columns are the same as in the table for shapes.

How to use the tables

Find the grade, then the row for the thickness of the rolled product. The yield and tensile strengths in the standard are guaranteed minimums: the actual values of a batch may be higher, and the design resistances for a project are taken from the current design codes for steel structures.

The mass of rolled metal does not depend on the grade: it is found from the handbook tables and the metal weight calculator. The grade of steel and its requirements for an order are given in the KM and KMD drawings.

Calculator and ordering

Other sections are collected in the rolled metal handbook. If you need a structure to your drawings with a specified steel grade, send them with the request and we will price fabrication and galvanizing.