Q355B

2 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.

Open condition selection, comparison and carbon-equivalent tools for Q355B →

Q355B · GB /T 1591-2018

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

Material category: Alloy steel
Subcategory: Alloy steel
Material form: Reference record
Original record status: Reference data; original source not verified
Standard edition: GB/T 1591-2018
Table / clause: Table 1 · Notes a–g

Carbon-equivalent reference

Estimates are presented separately for each applicable composition condition. Match the actual ordering conditions; ranges must not be combined.

Nominal thickness/diameter ≤30mm, Table 1 C≤0.24%

IIW / CEV：0.0000–0.6133Known-element contribution; incomplete value; missing Mo, V 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）：0.0000–0.3783Known-element contribution; incomplete value; missing 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：0.0000–0.4425Known-element contribution; incomplete value; missing Mo 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.

>30 to 40mm, under Table 1, note b, C≤0.22%

IIW / CEV：0.0000–0.5933Known-element contribution; incomplete value; missing Mo, V 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）：0.0000–0.3583Known-element contribution; incomplete value; missing 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：0.0000–0.4225Known-element contribution; incomplete value; missing Mo 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.

>40mm, note b, C≤0.22%; Sections >100mm require separate agreement

Composition record (conditional branches apply; this is not an unconditional requirement)

Element	Composition requirement
C	≤ 0.24 (lower limit not stated)
Si	≤ 0.55 (lower limit not stated)
Mn	≤ 1.6 (lower limit not stated)
P	≤ 0.035 (lower limit not stated)
S	≤ 0.035 (lower limit not stated)
Cr	≤ 0.3 (lower limit not stated)
Ni	≤ 0.3 (lower limit not stated)
Cu	≤ 0.4 (lower limit not stated)
N	≤ 0.012 (lower limit not stated)

Applicability and limitations

For sections and bars, the P and S maxima may each be increased by 0.005%. ; The Nb of Q390 and Q420 may reach a maximum of 0.07%, and the Nb of Q460 may reach a maximum of 0.11%; V and Ti may reach a maximum of 0.20%. ; When acid-soluble aluminum Als≥0.015%, total aluminum Alt≥0.020%, or other nitrogen-fixing alloying elements are present, N is unrestricted; Nitrogen-fixing elements must be specified in the quality certificate. ; For sections with a nominal thickness greater than 100mm, the C shall be negotiated between the supplier and the purchaser. ; The ≤40mm column in the table header includes Note b: for steel with a nominal thickness greater than 30mm, C ≤0.22%; Note b shall not be ignored to judge solely by the table header range. ; For Q355B, C ≤0.24% in the table; for Q355C/D, C ≤0.20% in the ≤40mm column and C ≤0.22% in the >40mm column; Simultaneously verify Note a, b and the actual form.

Original condition-branch records

Nominal thickness/diameter ≤30mm, Table 1 C≤0.24%

Element	Composition requirement
C	≤ 0.24 (lower limit not stated)
Si	≤ 0.55 (lower limit not stated)
Mn	≤ 1.6 (lower limit not stated)
P	≤ 0.035 (lower limit not stated)
S	≤ 0.035 (lower limit not stated)
Cr	≤ 0.3 (lower limit not stated)
Ni	≤ 0.3 (lower limit not stated)
Cu	≤ 0.4 (lower limit not stated)
N	≤ 0.012 (lower limit not stated)

>30 to 40mm, under Table 1, note b, C≤0.22%

Element	Composition requirement
C	≤ 0.22 (lower limit not stated)
Si	≤ 0.55 (lower limit not stated)
Mn	≤ 1.6 (lower limit not stated)
P	≤ 0.035 (lower limit not stated)
S	≤ 0.035 (lower limit not stated)
Cr	≤ 0.3 (lower limit not stated)
Ni	≤ 0.3 (lower limit not stated)
Cu	≤ 0.4 (lower limit not stated)
N	≤ 0.012 (lower limit not stated)

>40mm, note b, C≤0.22%; Sections >100mm require separate agreement

Element	Composition requirement
C	≤ 0.22 (lower limit not stated)
Si	≤ 0.55 (lower limit not stated)
Mn	≤ 1.6 (lower limit not stated)
P	≤ 0.035 (lower limit not stated)
S	≤ 0.035 (lower limit not stated)
Cr	≤ 0.3 (lower limit not stated)
Ni	≤ 0.3 (lower limit not stated)
Cu	≤ 0.4 (lower limit not stated)
N	≤ 0.012 (lower limit not stated)

A condition branch must be selected

Yes

Verification notes

The original standard, Table 1 has been checked; Applicable dimensions and footnotes must be used together

Q355B · GB /T 34199-2017

Original-source verification is incomplete; this is not a formal standard reference

Material category: Alloy steel
Subcategory: Alloy steel
Material form: Reference record
Verification status: Reference data; original source not verified

Carbon-equivalent reference

IIW / CEV: composition source not verified; standard-range carbon equivalent is not calculated

Pcm (Ito–Bessyo): composition source not verified; standard-range carbon equivalent is not calculated

CET: composition source not verified; standard-range carbon equivalent is not calculated

Composition

Element	Composition requirement
C	≤ 0.2 (lower limit not stated)
Mn	≤ 1.6 (lower limit not stated)
N	≤ 0.01 (lower limit not stated)
Nb	≤ 0.07 (lower limit not stated)
Ni	≤ 0.5 (lower limit not stated)
P	≤ 0.03 (lower limit not stated)
S	≤ 0.03 (lower limit not stated)
Si	≤ 0.5 (lower limit not stated)
Ti	≤ 0.2 (lower limit not stated)
V	≤ 0.15 (lower limit not stated)

Applicability and limitations

A match in the materials database does not establish suitability for cold heading or guarantee finished-product strength. Confirmation must consider wire condition, deformation, heat treatment and tests on actual parts.