Constitutional Schaeffler Diagram
The constructive Schaeffler diagram is a graphical tool for predicting the weld microstructure of high-alloy Cr-Ni steels. It helps estimate the proportions of austenite, ferrite, and martensite based on nickel and chromium equivalents.
Physical-Chemical Mechanism of Action
The Constructive Schaeffler Diagram uses the added amounts of nickel (Ni) and chromium (Cr) in a steel to predict the microstructure after welding. These elements influence the kinetics of phase transformations in the molten weld pool and determine the formation of the weld metal microstructure.
Metallurgical Relevance & Risks in Welding
The diagram helps optimize the welding process to achieve a desired microstructure. Inaccurate welding can lead to an undesirable amount of martensite, which increases hardness and reduces toughness. Excessive austenite content leads to lower strength and scale resistance.
Workshop Practice & Instructions
To use the diagram, determine the nickel and chromium equivalents of the steel. Mark the corresponding position on the diagram and identify the expected microstructure. During welding, pay attention to the correct temperature curve and cooling time to achieve the desired microstructure. Use special welding methods such as TIG or MIG with a shielded environment for high-alloy steels.