DeLong Diagram
The DeLong diagram is an extended version of the Schaeffler diagram, specifically for austenitic chromium-nickel weld metal. It considers ferrite content and nitrogen to predict ferrite more precisely and avoid solidification cracks.
Physicochemical Mechanism of Action
The DeLong diagram extends the Schaeffler diagram by incorporating the influence of ferrite content and nitrogen on the microstructure evolution of austenitic chromium-nickel weld metal. It shows how ferrite content behaves during cooling based on these additions.
Metallurgical Relevance & Welding Risks
Too high a ferrite content can lead to solidification cracking because the material is less flexible and more prone to cracking in this phase. The DeLong diagram helps control this process and minimize risks.
Workshop Practice & Instructions
To effectively use the DeLong diagram in the workshop, follow these steps:
• Determine the ferrite content and nitrogen content in the material.
• Use the diagram to set the optimal cooling time and temperature.
• Make sure the welding process maintains these values to avoid solidification cracking.