Y15 · GB/T 8731-2008
Free-cutting structural steel; hot-rolled bar and wire-rod hardness conditions stated separately · 7.1.1/Table 1 · PDF page 7 · Mass fraction %
| Element | Heat analysis / guide composition |
|---|---|
| C | 0.1～0.18 |
| Si | ≤0.15 |
| Mn | 0.8～1.2 |
| P | 0.05～0.1 |
| S | 0.23～0.33 |
Verified against the actual original text of GB/T 8731—2008 Table 1; Composition is the heat analysis mass fraction wt%; elements not listed shall not be filled as 0. This standard applies to free-cutting structural steels; Default is UC for machining; UP for pressure processing must be specified in the contract; Supply purpose or cold heading applicability cannot be inferred solely from the grade. Allowable deviations for product analysis of S and Sn are given in Table 5 of 7.1.3; Separated from heat analysis boundaries; other elements follow GB/T 222 and have not been verified item by item. The upper limit of HBW in Table 6 applies only to bars and wire rods delivered in the hot-rolled condition; Mechanical properties for other conditions/products or Annex A require confirmation under the supplier-purchaser agreement and must not be applied automatically. Additional examinations for macrostructure, decarburization and inclusions follow purchaser requirements and the applicable clauses; without agreement, they must not be treated as already performed.
Properties and applicable conditions
| Condition | Requirement |
|---|---|
| Maximum Brinell hardness HBW of hot-rolled bars and wire rod | ≤170 |
Original source: GB/T 8731—2008
Illustrative packaging
Illustrative company wire products and packaging; the images do not identify the listed grade’s heat or batch, current stock, or default delivery conditions.