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Microstructure estimation
Schaeffler and DeLong Diagrams
Graphical evaluation of Cr and Ni equivalents with the original WeldExp diagram engine.
The diagrams of the Weldability Calculator primarily support preliminary weldability assessment of high-alloy, corrosion-resistant and creep-resistant steels. Chromium and nickel equivalents can be used to estimate the expected weld-metal microstructure, ferrite content and the risk of several unfavourable structural phenomena that may occur during or after welding.
The diagrams support engineering orientation and preliminary procedure planning. For final welding-technology decisions, the applicable standards, material and welding-consumable manufacturer documentation, and the approved welding procedure must be treated as the primary sources.
Schaeffler–Bystram Diagram
The Schaeffler diagram shows the expected austenitic, ferritic and martensitic microstructure regions based on chromium and nickel equivalents. The Bystram extension marks additional weldability hazard zones, helping visual assessment of cracking and other metallurgical risks alongside microstructure estimation.
Modified Schaeffler Diagram
The modified Schaeffler diagram can be used over a wider range of chromium and nickel equivalents, making it particularly useful for preliminary comparison of highly alloyed materials and combinations with differing compositions.
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DeLong Diagram
The DeLong diagram is a supplementary diagram for more refined estimation of ferrite content in stainless weld metal. It enables more detailed ferrite-content assessment within a narrower Cr- and Ni-equivalent range.
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