Tools · Solidification Cracking

WRC-1992 / Schaeffler / Suutala Diagram

Enter the composition of up to three alloys (e.g. base metal, filler, and a second base metal for dissimilar joints) and a single dilution value. The tool calculates Creq/Nieq for each diagram, plots tie lines between them, and estimates the diluted weld metal's solidification mode, Schaeffler phase, and solidification-cracking risk (including a rapid-solidification/laser-welding comparison).

⚠ Disclaimer: Use at Your Own Risk This tool is provided "as is," for general engineering reference and educational purposes only, with no warranty of any kind, express or implied, including any warranty of accuracy, completeness, or fitness for a particular purpose. Creq/Nieq formulas are the standard published Schaeffler and WRC-1992 equivalents; the boundary lines, iso-FN, and %ferrite contours are engineering approximations reconstructed from the published Kotecki & Siewert (1992) and Schaeffler (1949) figures (see the sourcing note below the charts) and are not a certified or pixel-exact digitization. Jeffrium and Jeffrey Sowards assume no liability for decisions, designs, procedures, or outcomes based on this tool's output. Do not use these results as the sole basis for procedure qualification, code compliance, safety-critical, or contractual decisions; verify independently against current reference standards (e.g. AWS A4.2, ASME Section IX) and, where required, qualified testing. Use of this tool is entirely at your own risk.

Dilution

Base metal dilution, D (%): fraction of the weld pool melted from base metal

Filler contributes the remainder: 70%

WRC-1992 Diagram

Creq = Cr + Mo + 0.7·Nb · Nieq = Ni + 35C + 20N + 0.25Cu

Diluted Weld Metal Composition

Boundary and contour lines are approximate, reconstructed from D.J. Kotecki & T.A. Siewert, "WRC-1992 Constitution Diagram for Stainless Steel Weld Metals," Welding Journal 71(5), 1992; A.L. Schaeffler, "Constitution Diagram for Stainless Steel Weld Metal," Metal Progress 56, 1949; and N. Suutala's solidification-cracking work as compared against rapid-solidification (laser) behavior in the Lippold/Pacary literature. The Suutala/Lippold cracking-lobe boundaries are a first-pass hand-estimate from the source figures, not yet a calibrated digitization, so treat the exact threshold position as indicative only until refined. It is not a certified digitization; see disclaimer above.

How it works

How the WRC-1992, Schaeffler, and Suutala diagrams work

Each diagram combines ferrite-forming elements into a chromium equivalent and austenite-forming elements into a nickel equivalent, then plots one against the other to predict the weld's microstructure.

The math

CreqCr + Mo + 0.7Nb

NieqNi + 35C + 20N + 0.25Cu

DilutionC_weld = D·C_base + (1−D)·C_filler

EquivalentsWRC-1992 versions shown

Dfraction of weld melted from base metal

FNFerrite Number

Worked example

Given316L base, ER308L filler, 30% dilution

Weld metalCreq 19.73, Nieq 12.32

WRC-1992FA mode, about 7 FN

Suutalaratio 1.67, P + S 0.036%

ResultArc OK, laser at risk

Rapid solidification can switch a weld to primary austenite, so a composition that's fine for arc welding can still crack under a laser.

More detail

Which diagram should I use?

Diagram	Best for
WRC-1992	Ferrite Number and solidification mode in austenitic and duplex weld metal. Referenced in ASME Section III.
Schaeffler	Wider range, including martensitic and stainless-to-carbon steel welds. Ignores nitrogen, so it overpredicts ferrite in N-bearing alloys.
Suutala	Solidification cracking risk from the Creq/Nieq ratio and P + S, with an added pulsed-laser zone.

Why ferrite content matters

Welds that solidify as primary austenite (A and AF modes) are prone to cracking, because austenite dissolves little sulfur or phosphorus and these collect in the last liquid. Primary ferrite (FA mode) is far more resistant, so most austenitic fillers deposit a few FN. Too much ferrite brings its own problems: sigma embrittlement at high temperature and lower toughness at cryogenic temperature.

How dilution is handled

Because the equivalents are linear in composition, the weld always plots on the straight tie line between filler and base metal, a fraction D of the way toward the base metal. For dissimilar joints, D is split between two base metals. Autogenous welds have 100% dilution.

References

D.J. Kotecki and T.A. Siewert, Welding Journal 71(5), 1992, 171-s.
A.L. Schaeffler, Metal Progress 56, 1949, 680.
N. Suutala, Metallurgical Transactions A 14, 1983, 191–197.
J.C. Lippold, Welding Journal 73(6), 1994, 129-s.
J.C. Lippold and D.J. Kotecki, Welding Metallurgy and Weldability of Stainless Steels, Wiley, 2005.