Understanding Carbide Hardness Testing

Introduction

Hardness is the most commonly measured property of cemented carbide. Understanding hardness testing helps ensure quality and grade consistency.

Rockwell A Scale

Carbide hardness is typically measured on the Rockwell A scale, abbreviated HRA. This scale uses a diamond indenter and 60 kilogram load, suitable for very hard materials.

Typical Hardness Ranges

YG6 measures 89 to 91 HRA, YG8 measures 88 to 90 HRA, YG15 measures 87 to 89 HRA, and YG20 measures 85 to 87 HRA. Hardness decreases as cobalt content increases.

Why Hardness Matters

Hardness correlates directly with wear resistance. Harder carbide grades last longer in abrasive applications. However, they are also more brittle, so hardness must be balanced with toughness.

Testing Procedure

Hardness testing requires flat, polished surfaces. Several measurements are taken and averaged. Surface roughness and specimen thickness affect accuracy.

Quality Control

Every batch of carbide should be hardness tested. Consistent hardness confirms correct grade composition and proper sintering.

Conclusion

Hardness testing is fundamental to carbide quality control. Understanding HRA scales and typical ranges helps select the right grade and verify material quality.

References

GB/T 7714: GUPTA R, SONG J. Powder metallurgy processing and mechanical properties of cemented tungsten carbide composites[J]. International Journal of Refractory Metals and Hard Materials, 2020, 91: 105246.

APA 7th: Gupta, R., & Song, J. (2020). Powder metallurgy processing and mechanical properties of cemented tungsten carbide composites.

MLA 9th: Gupta, R., and J. Song. "Powder Metallurgy Processing and Mechanical Properties of Cemented Tungsten Carbide Composites."