GB/T 5686.5-2023 in English

Interpretation of the core content of the standard

The new version of GB/T 5686.5-2023 standard replaces the 2008 version, and mainly proposes four methods for the determination of carbon content in ferromanganese, silicomanganese alloy, ferromanganese nitride and metallic manganese:

Key Technical Changes

Main revisions to the 2023 version of the standard:

• Delete the determination requirements for electrolytic manganese metal and blast furnace ferromanganese
• Strictly stipulate the purity standards for tungsten particles (carbon < 0.0005%) and tin particles (carbon < 0.00005%)
• Add new requirements for the number of determinations (at least 2 independent determinations)
• Use repeatability limit (r) and reproducibility limit (R) to replace the original allowable difference expression
• Add normative Appendix A (result acceptance procedure flow chart)

Infrared absorption method operation points

Method selection recommendations

Recommendations based on material type and carbon content range:

• Conventional testing: Infrared absorption method is preferred (wide applicability and high efficiency)
• Arbitration analysis: Gravimetric method is recommended for high carbon (＞4%) samples
• Low content of metallic manganese: Coulometric method has the best sensitivity

Implementation precautions

Laboratories need to pay attention to:

1. Carbon background value needs to be tested for flux batches
2. Channels of different ranges need to be calibrated separately
3. Blank calibration should be performed again when the ambient temperature changes by ＞5℃
4. Manganese silicon alloy samples need to be ground to <0.125mm