controlled heat analysis · two named equations · no welding verdict

Steel Carbon-Equivalent Formula Worksheet

Calculate CE_IIW and P_εκ. from one documented chemical analysis. The governing material specification or welding code—not this worksheet—decides which equation and limits apply.

elements entered as mass %B accepts mass % or ppmdimensionless mass-% indices

Not a grade-equivalence, weldability, preheat or WPS selector. A carbon-equivalent index is a composition-characterising parameter. It does not by itself determine cracking risk, weldability, preheat, PWHT, mechanical properties or compliance.

Documented chemical analysis and traceability

Carbon C (mass %)required non-negative plain decimal

Silicon Si (mass %)used by Pcm; CEIIW does not contain Si

Manganese Mn (mass %)

Chromium Cr (mass %)

Molybdenum Mo (mass %)

Vanadium V (mass %)

Nickel Ni (mass %)

Copper Cu (mass %)

Boron B valuePcm includes 5B; enter the controlled reported value

Boron B input unit

Calculation record ID

Material, heat and sample identifiers

Material test certificate / laboratory report and revision

Controlled product specification and grade

Product form, delivery condition and thickness

Analysis type, laboratory method and uncertainty

Composition basis and unit confirmation

Below-detection / less-than-value treatment

Required equation source, edition and clause/table record

Governing code, contract, WPS/PQR or material requirement

Responsible welding/materials engineer / reviewer

Review date

Notes and exclusionsOptional: report qualifiers, sampling location, heat treatment, hydrogen, heat input, restraint and joint variables.

All nine element values come from the same controlled heat/sample analysis, use the stated mass basis, and every reported “less than” or below-detection value has a documented treatment.
The required carbon-equivalent equation and any permitted composition range were verified in the governing current specification; neither equation is assumed universal.
No EN/AISI/SAE/DIN/JIS grade equivalence, strength, hardness, toughness or delivery-condition property will be inferred from these indices.
No weldability, hydrogen-cracking risk, preheat, interpass, PWHT, WPS/PQR or acceptance decision will be inferred from CEIIW or Pcm alone.

Composition indices

CEIIW

—

Pcm (Ito–Bessyo)

—

CEIIW contribution check

—

Pcm contribution check

—

Normalized boron B

—

Entered-element subtotal

—

Equations, units and classification

CEIIW = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15
Pcm = C + Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B
Bmass% = Bppm / 10 000

Ποσότητα	Input basis	Meaning and boundary
C, Si, Mn, Cr, Mo, V, Ni, Cu, B	mass percent; B may be converted from ppm by mass	controlled chemical-analysis values for one heat/sample; not nominal website presets
CEIIW	dimensionless index reported on the mass-% convention	IIW composition-characterising equation; not a universal weldability class or code acceptance value
Pcm	dimensionless index reported on the mass-% convention	Ito–Bessyo equation developed for lower-carbon steels; applicability must come from the governing specification

Because every term is a mass percentage multiplied by a dimensionless coefficient, each index is dimensionless. Industry documents commonly print the numeric result with a “%” convention; this worksheet shows the numeric index and its explicit mass-% input basis.

Removed unsafe claims

No grade cross-reference database. Labels such as S235JR, A36, SS400, 42CrMo4 and 4140 are not declared interchangeable. Exact chemistry, product form, delivery condition, dimensions, testing and properties must be checked in the applicable specifications and certificate.
No invented compositions or strengths. The old table’s single C/Mn/alloy values and Rp/Rm values were uncontrolled presets, not certificate data or complete grade limits.
No CE threshold verdict. “Good/fair/poor” bands and universal 50–300 °C preheat outputs were removed. Hydrogen level, heat input, restraint, joint geometry, thickness, consumables, process, ambient conditions and the governing code matter.
No missing boron term. The old displayed Pcm equation included 5B while its code omitted B. Boron is now an explicit controlled input with mass-%/ppm conversion.
No universal equation claim. Nippon Steel’s current product catalogue visibly uses a product-specific Ceq equation different from CEIIW, while its Pcm equation includes 5B. Formula choice is specification-dependent.
No hidden state. Defaults, URL parameters, local history, automatic grade calculation, clipboard output, dynamic HTML and external KaTeX were removed.

Source traceability

Claim	Ταξινόμηση	Evidence
ISO/TR 17671-2:2002 Edition 1 remains current after confirmation in 2022 and gives arc-welding guidance for ferritic steels, excluding ferritic stainless steels.	Official ISO status and scope; not used as an unverified clause-level formula source	ISO/TR 17671-2:2002
AWS D1.1/D1.1M:2025 is the 25th edition for welded structures made from commonly used carbon and low-alloy constructional steels; AWS now lists the 2025-AMD1 publication. Exact preheat and qualification rules are not reproduced here.	Official AWS edition/scope and amendment status	AWS D1.1/D1.1M:2025-AMD1
TWI publishes CEIIW exactly as used here and explains that carbon-equivalent equations were developed for different steel populations; Pcm was developed for lower-carbon steels.	Authoritative welding research/technical source	TWI CEIIW equation; TWI formula scope
Nippon Steel’s 2025 steel-plate catalogue, PDF page 9 (printed pages 14–15), gives Pcm with the 5B term and displays a different product-specific Ceq equation, demonstrating why the equation source must be controlled.	Manufacturer product document; page visually inspected	Nippon Steel A001en, PDF p. 9

Accessed: 15 July 2026. Exact grade equivalence, chemical limits, mechanical-property tables, AWS/EN preheat rules and acceptance criteria remain NEEDS_LICENSED_SOURCE.

Reference check

For C=0.18, Si=0.40, Mn=1.50, Cr=0, Mo=0, V=0.05, Ni=0, Cu=0 and B=0 mass %, CEIIW=0.44 and Pcm=0.273333333333. If B is entered as 20 ppm instead, B=0.002 mass % and Pcm increases by 0.01 while CEIIW is unchanged.

Questions

Does a lower result prove that welding is safe?

No. Use the governing material and welding specification, qualified WPS/PQR and engineering review of hydrogen, heat input, restraint, thickness, process, consumables and service requirements.

Can this identify an equivalent steel grade?

No. Cross-designation requires a requirement-by-requirement comparison of current specifications and the actual certificate; similar names or nominal compositions are not proof of equivalence.

Why calculate both equations?

Only to reproduce two named arithmetic definitions. The applicable specification decides whether CEIIW, Pcm, another equation or no carbon-equivalent index is required.