← Glossary
DeLong Diagram for Austenitic Weld Metals
The DeLong diagram extends the Schaeffler concept with ferrite content and residual nitrogen to precisely control delta ferrite and prevent solidification cracking.
Physicochemical Mechanism of Action
The DeLong diagram is based on the relationship between ferrite content (F), residual nitrogen (N), and temperature. It shows how delta ferrite (Df = F - N) changes in austenite.
Metallurgical Relevance & Welding Risks
Too high a delta ferrite content leads to solidification cracking and increases the stress resistance of the weld. The DeLong diagram helps keep this content optimal.
Workshop Practice & Instructions
Use the diagram to determine ferrite content and residual nitrogen in austenite. The target is a delta ferrite between 0.5% and 1%. If Df is too high (above 2%), the weld can become prone to cracking.
MetallurgieSchweißtechnik