Equivalent Carbon Content (CE / Pcm)

Universal

The IIW carbon equivalent and Ito-Bessyo Pcm quantify the risk of hydrogen-induced cold cracking (HICC) in the heat-affected zone during welding and directed energy deposition. Both metrics combine alloy composition into a single number that drives preheat requirements. High CE alloys (tool steels, high-strength steels) need careful thermal management in LPBF and DED to avoid HAZ cracking and delamination.

Material presets

Click to load a common AM/DED steel composition.

LPBF / DED. High CE — 150–200°C preheat mandatory.

Composition (wt%)

Enter elemental composition in weight percent. All fields required.

CarbonC

wt%

ManganeseMn

wt%

SiliconSi

wt%

ChromiumCr

wt%

MolybdenumMo

wt%

VanadiumV

wt%

NickelNi

wt%

CopperCu

wt%

BoronBonly affects Pcm

wt%

Results

CE (IIW)CE_IIW

Above typical window

1.938

Pcm (Ito-Bessyo)Pcm

0.8790

Valid for C < 0.18 wt%

Estimated preheat

455.0°C

Per EN ISO 13916 / Seferian

Weldability / printabilityPoor

High preheat (200°C+). Significant cold-cracking risk — consider post-weld HT.

Composition contribution table

Breakdown of each element's contribution to CE_IIW, sorted by impact.

Element	wt%	Contribution to CE_IIW	% of total CE
Cr	5.10	1.020	52.6%
C	0.380	0.3800	19.6%
Mo	1.35	0.2700	13.9%
V	0.950	0.1900	9.8%
Mn	0.350	0.05833	3.0%
Ni	0.200	0.01333	0.7%
Cu	0.100	0.006667	0.3%
Total		1.938	100.0%

IIW Carbon Equivalent

CE_IIW = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15

C: Carbon[wt%]
Mn: Manganese[wt%]
Cr: Chromium[wt%]
Mo: Molybdenum[wt%]
V: Vanadium[wt%]
Ni: Nickel[wt%]
Cu: Copper[wt%]

IIW formula per ISO/TR 17671-2. Valid for carbon and low-alloy steels with C > 0.18%. For lower-carbon steels use Pcm.

Ito-Bessyo Pcm

Pcm = C + Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B

C: Carbon[wt%]
Si: Silicon[wt%]
Mn: Manganese[wt%]
Cu: Copper[wt%]
Cr: Chromium[wt%]
Ni: Nickel[wt%]
Mo: Molybdenum[wt%]
V: Vanadium[wt%]
B: Boron[wt%]

Preferred for C < 0.18%. Developed by Ito & Bessyo (1968) for low-carbon high-strength structural steels.

Preheat estimate

T_preheat ≈ 350 × √(CE_IIW − 0.25)    [°C, when CE > 0.25]
T_preheat = 0                            [when CE ≤ 0.25]

T_preheat: Minimum preheat temperature[°C]
CE_IIW: IIW carbon equivalent[—]

Seferian empirical formula. Conservative estimate — actual preheat may be lower with hydrogen-controlled processes (low-H electrodes, dry shielding gas). Per EN ISO 13916.

Interpretation notes

AM contextIn LPBF, rapid solidification and the powder-bed preheating effect partially mitigate HICC, but high-CE alloys (CE > 0.6, e.g. H13) still require platform preheating to 150–200°C to prevent delamination and micro-cracking.

DED & WAAMMulti-pass DED builds accumulate heat; monitor interpass temperature to stay above preheat but below overtemper limits. H13 must not exceed 250°C interpass or secondary carbides coarsen.

Applicability limitsCE_IIW was developed for ferritic/martensitic steels. For austenitic stainless steels (316L), the dominant failure mode is hot cracking (Schaeffler diagram, Creq/Nieq), not HICC. For 17-4PH, martensite hardening is the concern.

Sources

[1]IIW (1967) — Carbon equivalent formula, Doc. IX-555-67
[2]Ito, Y. & Bessyo, K. (1968) — Weldability formula of high-strength steels — IIW Doc. IX-576-68
[3]EN ISO 13916:2017 — Welding: Guidance on the measurement of preheating temperature, interpass temperature and preheat maintenance temperature
[4]AWS D1.1:2020 — Structural Welding Code — Steel, Table 4.5 preheat requirements
[5]Kempen, K. et al. (2012) — Microstructure and mechanical properties of selective laser melted 18Ni-300 and H13 tool steel — Phys. Proc. 39, 255–263

Related tools

Thermal Distortion Risk — residual stress and distortion risk for metal AM builds
Heat Treatment Advisor — post-build heat treatment cycles for AM steels
DfAM Checklist — design-for-additive checklist including material screening
DED / WAAM Applications — process guides and material selection for directed energy deposition