Schaeffler Diagram for Different Base Materials

When welding different materials, complex microstructures arise. The Schaeffler diagram helps predict these and avoid risks such as cracking or brittleness. It is an important tool in selecting suitable filler materials.

capilla uses such calculations to develop safe solutions for dissimilar metal joints.

The diagram itself does not prevent defects, but it helps identify critical microstructure states at an early stage. This allows suitable filler materials and welding parameters to be selected. In combination with experience and technical evaluation, risks can be significantly reduced.

capilla combines calculation tools with practical experience to avoid welding defects in demanding applications.

The Schaeffler diagram shows the microstructure in the weld metal when combining different base materials. As a simplified phase diagram it enables classification of the resulting material mixture based on the chemical composition and the alloying elements present.

Interpretation is based on the position in the Schaeffler diagram, which results from the calculated chromium and nickel equivalents. Depending on the location, conclusions can be drawn about the microstructure and the behaviour of different steel types.

capilla supports the application of the Schaeffler diagram and its practical implementation in industrial welding processes.

The Schaeffler diagram distinguishes regions in which austenite, ferrite or martensite predominantly occur. These phases correspond to the typical microstructure states also described in a metallurgical phase diagram.

By classifying within the Schaeffler diagram, the expected microstructure can be estimated. The position within the regions for austenite, ferrite and martensite shows which phases dominate in the weld metal.

Chromium and nickel equivalents are calculated characteristic values that summarise the effect of various alloying elements on the microstructure.

• Chromium equivalent influences ferritic properties

• Nickel equivalent influences austenitic properties

These values are used to classify materials in the Schaeffler diagram.

Austenitic steels are characterised by higher nickel equivalents and lie in the austenite region, while ferritic steels are shifted towards ferrite due to higher chromium equivalents. These differences are directly reflected in the Schaeffler diagram.

Corrosion resistance depends on the chemical composition and the microstructure. The Schaeffler diagram allows indirect recognition of whether a material tends more towards the austenitic or ferritic region, which permits conclusions about its resistance.

No. The Schaeffler diagram provides important guidance, but does not replace a complete welding engineering assessment.
Additional factors such as:

• Component geometry

• Heat input

• Preheating

• Mechanical loading

must also be taken into account.

capilla supports the holistic assessment of welded joints and material combinations.