Schaeffler Diagram for Weld Metal
The Schaeffler diagram shows the microstructure in high-alloy chromium-nickel welds based on chromium and nickel equivalents. It helps predict hardness and toughness.
Physical-Chemical Mechanism of Action
The Schaeffler diagram visualizes the change in microstructure in high-alloy chromium-nickel weld seams. It takes into account the concentration of chromium and nickel, which are represented as chromium and nickel equivalents. These values determine whether the microstructure remains austenitic or martensitic.
Metallurgical Relevance & Risks in Welding
If the chromium and nickel content is too high, the microstructure can become austenitic, which offers higher toughness and dimensional stability. However, it can also lead to increased hardness, which can cause cracks and stress failure. Conversely, too low a content can lead to a martensitic microstructure, which is glass-hard and prone to cracking.
Workshop Practice & Action Instructions
Use the Schaeffler diagram to determine the chromium and nickel content in the weld seam. Ensure that the content is within the safe range to guarantee a sufficiently tough and dimensionally stable seam. If necessary, adjust the additives or the welding process to keep the microstructure in the optimal range.