WUY Diagram for Weld Metal
The WUY diagram shows the phase composition of austenitic-ferritic duplex weld joints as a function of temperature and time. It helps avoid intermetallic phases that can lead to cracking.
Physicochemical Operating Principle
The WUY diagram (Heat-Time-Yield) visualizes how the phase composition in austenitic-ferritic duplex weldments changes during thermal cycles. It shows when and under which conditions intermetallic phases such as σ-phase or γ'-phase form.
Metallurgical Relevance & Welding Risks
Intermetallic phases can lead to cracks and loss of ductility. The WUY diagram helps to avoid these phases by specifying the optimal cooling time and temperature for the weld metal.
Workshop Practice & Instructions
To apply the WUY diagram correctly:
• Determine the specific properties of the austenitic-ferritic duplex weld metal (e.g., chemical composition).
• Read the thermal cycle that occurs during the welding process.
• Use the WUY diagram to determine the cooling time and temperature that prevent the formation of intermetallic phases.
• Ensure that cooling stays within the defined range in the diagram to avoid cracks and loss of ductility.