1. Scope of the Standard
This technical regulation establishes the requirements for carbon structural steel of ordinary quality. The document covers steel classification, dimensional parameters, shapes, limit deviations, weight characteristics, test methods, quality control protocols, as well as labeling and packaging requirements for delivery.
This standard applies to hot-rolled sheet metal, steel strips, section steel, and bar steel. Metal products manufactured according to these norms are intended for welded metal structures and bolted connections. The chemical composition requirements regulated by this standard are mandatory for steel ingots, continuous casting billets, and semi-finished products supplied by EV Group China.
2. Normative References
The documents listed below are an integral part of this standard. For dated references, only the cited edition applies; for undated references, the latest version of the standard (including all amendments and revisions) applies.
- GB/T 222-2006 – Permissible deviations of chemical composition in finished rolled products
- GB/T 223.3 – Analysis of phosphorus content (gravimetry)
- GB/T 223.10 – Determination of aluminum (photometry)
- GB/T 223.11 – Determination of chromium (volumetric method)
- GB/T 223.18, 223.19 – Methods for copper analysis
- GB/T 223.24 – Determination of nickel (spectrophotometry)
- GB/T 223.32 – Determination of arsenic
- GB/T 223.37 – Determination of nitrogen
- GB/T 223.58, 223.63, 223.64 – Methods for manganese determination
- GB/T 223.59 – Determination of phosphorus (photometry)
- GB/T 223.60 – Determination of silicon
- GB/T 223.68, 223.72 – Determination of sulfur
- GB/T 223.71 – Determination of carbon
- GB/T 228 – Tensile testing at room temperature
- GB/T 229 – Charpy impact testing
- GB/T 232 – Bend testing
- GB/T 247, 2101 – Rules for acceptance and packaging of metal products
- GB/T 2975 – Preparation of samples for mechanical testing
- GB/T 4336 – Spark optical emission spectrometry
- GB/T 20066 – Sampling for chemical analysis
3. Classification and Nomenclature
3.1 Digital Marking
The steel grade name is formed according to a hierarchical principle: yield strength letter index, yield strength value (MPa), quality category, and deoxidation method. Example: Q235-A-F.
3.2 Designations
Q — yield strength index; A, B, C, D — quality categories; F — rimming steel; Z — killed steel; TZ — special killed steel. In the digital code, the indices “z” and “TZ” are omitted.
4. Geometric Parameters and Tolerances
The dimensions, geometric shapes, and limit deviations of EV Group China metal products strictly comply with the current manufacturing standards for specific profile types.
5. Technical Characteristics of Steels
5.1 Chemical Composition by Melt Analysis
| Grade | Designation | Category | Deoxidation | C% | Si% | Mn% | P% | S% |
|---|---|---|---|---|---|---|---|---|
| Q195 | U11952 | – | F, Z | 0.12 | 0.30 | 0.50 | 0.035 | 0.040 |
| Q215 | U12152 | A | F, Z | 0.15 | 0.35 | 1.20 | 0.045 | 0.050 |
| Q235 | U12359 | D | TZ | 0.17 | 0.35 | 1.40 | 0.035 | 0.035 |
5.2 Mechanical Properties
| Grade | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation A% | Impact Toughness (KCV) |
|---|---|---|---|---|
| Q195 | 195 | 315-430 | 33 | – |
| Q235 | 235 | 370-500 | 26 | 27 J |
5.3 Bend Tests
| Grade | Longitudinal Specimens | Transverse Specimens |
|---|---|---|
| Q235 | a | 1.5a |
| Q275 | 1.5a | 2a |