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Y45SN

1 source records. Standards, editions and conditions are presented separately; matching grade names do not establish interchangeability.

Refer to each source for mass fractions and analysis type. Missing values are not treated as 0. Manufacturer typical values, standard guarantees and measured heat results must remain separate. Use the material selector for calculations and condition selection.

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Y45Sn · GB/T 8731-2008

Chemical composition source verified; this does not verify every standard clause, actual supply or measured heat results

Material category
Carbon steel
Subcategory
Free-cutting steel
Material form
Free-cutting structural steel; hot-rolled bar and wire-rod hardness conditions stated separately
Original record status
Original standard verified
Standard edition
GB/T 8731—2008
Table / clause
7.1.1/Table 3
PDF page references
8
Unit
Mass fraction (wt%)
Analysis type
Heat analysis

Carbon-equivalent reference

IIW / CEV:0.5000–0.6467 Known-item contribution, not a complete value; missing Cr, Mo, V, Ni, Cu CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15; an engineering estimate of welding cold-cracking susceptibility for carbon and low-alloy steels.
Pcm(Ito–Bessyo):0.4300–0.5433 Known-item contribution, not a complete value; missing Cu, Cr, Ni, Mo, V, B Pcm = C + Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B; mainly used for low-carbon low-alloy steels, particularly modern low-carbon pipeline steels; more relevant when C is approximately no higher than 0.11%.
CET:0.4600–0.5800 Known-item contribution, not a complete value; missing Mo, Cr, Cu, Ni CET = C + (Mn + Mo)/10 + (Cr + Cu)/20 + Ni/40; used in welding preheat assessment for ferritic steels, subject to the applicability conditions of EN 1011-2.

Composition

ElementComposition requirement
C0.4 ~ 0.48
Si≤ 0.4 (lower limit not stated)
Mn0.6 ~ 1.0
P0.03 ~ 0.07
S≤ 0.06 (lower limit not stated)
Sn0.09 ~ 0.25

Applicability and limitations

Verified against the actual original text of GB/T 8731—2008 Table 3; 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. The tin-containing grades in Table 3 carry a patent note.; Only chemical compositions listed in the original text of the standard are recorded; no inference of permission or supply is made.

Verification notes

All 22 grades in edition 2008, Table 1—4 and hot-rolled hardness conditions in Table 6 were checked row by row; Requirements of edition 2025 are not inferred on this basis.

Permitted product-analysis deviations

S
Additional source notes
0.03
Additional source notes
0.04
Sn
Additional source notes
0.03
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