Flux Basicity Index Calculator

Calculate the Boniszewski basicity index (BI) for submerged arc welding flux from its chemical composition to predict weld metal properties

Input Parameters

Results

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Basicity Index (BI)
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Flux Type Classification
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Predicted Weld O2 Content
ppm
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Impact Toughness Tendency
Note: The Boniszewski basicity index is the primary indicator of flux quality for SAW. Basic fluxes (BI > 1.5) produce cleaner weld metal with lower oxygen and better Charpy impact values.

Reference

Boniszewski Basicity Index: BI = (CaO + MgO + CaF2) / (SiO2 + 0.5*Al2O3) Acidic: BI < 0.9 | Neutral: 0.9-1.2 | Semi-Basic: 1.2-2.0 | Basic: BI > 2.0 Higher BI = Lower weld metal oxygen = Better toughness Basic fluxes: BI > 1.5 recommended for critical low-temperature service Oxygen content approximation: O2 ~ 900 - 300*ln(BI) ppm