MAXIMUM HARDNESS HRA 2

[AlexisViteri]

Dear experts,

I have received an inspection report (WC-6%Co)which refer a value of 92 HRA but in ASTM E18 -05 the scale doesn't reach that value please your comments.
Could you please explain why Izod or Charpy are not applied over WC.

Thanks

 

[metengr]

Was Vickers Hardness performed and someone tried to convert to HRA scale using a conversion formula? I have seen this done for cemented carbides. Your second question is unclear to me. Izod or Charpy are impact test methods, and would be applied if requested for testing to determine impact energy values.

 

[TVP]

Cemented carbide producers frequently use the HRA scale. ASTM E18 is for metallic materials. Cemented carbide is hardness tested according to ASTM B294.

http://www.generalcarbide.com/grade-selection-guide.php

http://blank.mitsubishicarbide.com/mmc/en/product/material/

http://www.kennametal.com/content/d...tunsten_carbide_metalforming_grades_chart.pdf

http://www.astm.org/Standards/B294.htm

 

[dbooker630]

ASTM B294-10 notes a 93 HRA value as part of a series of nominal hardness test blocks.

 

[AlexisViteri]

Gents,thank you for your prompt response, the first question is totally cleared.
Do you have some reference regarding Charpy or Izod test over WC-6%Co?

Thanks ins advance

 

[redpicker]

You are not likely to find much on Charpy or Izod impact testing on sintered WC. This test is generally used to quantify the impact toughness of the material, but the toughness is so low with sintered WC that even with un-notched specimens, very little information is gained from these tests. I have seen drop-weight tests used to evaluate toughness of these materials, but, honestly, that was over 30 years ago and I have not dealt with these materials much since, so I have no idea where the state of the art is today. Perhaps trying to research drop-weight testing WC-6%Co will provide you with some leads.

rp

 

[kumkumvijay]

Generally the high hardness material will have very small amount of plastic deformation during impact load, so the impact test and results are not much widely available or useful for high hardness material.

 

[AlexisViteri]

Thanks to all,

This was for a corrective action, I guess I will make a drop weight test.

Cheers!

 

[tbuelna]

As others noted, the Charpy and Izod tests were developed for metallic materials that have some ductility. The primary difference between the two tests is how the specimens are constrained. The results from these tests using a specimen of WC would not be valid, due to extremely low ductility of the material. You might take a look at ASTM C1421-10.