5 kg and 10 kg load for portable vickers hardness test 1

[replica]

Dear all,

Is there any difference in the hardness values when using 5 kg load and 10 kg load for portable vickers hardness tester model kraukramer Microdur UCI MIC 10?

 

[Metalero]

Yes, there may be a difference because the method, in addition to being sensitive to the applied test force, which must coincide with the application, is also sensitive to the surface quality and the roughness of the material. While smooth and homogeneous surfaces can be tested with low test loads, the rougher, coarser surfaces require the highest possible test loads.

 

The last time I used one of these units the only display options were HB, HV and HRB/C.
The Microdur UCI MIC 10 does not used indentation loads and does not differentiate between types of Vickers tests.
The user manual should describe the required surface finish.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[replica]

Thank you for the comment. If I has a mirror finish surface after polishing using 3 um ...Does it really matter if I use 5 kg or 10 kg load?

 

[Metalero]

ironic Metal
Test force in UCI hardness testing is defined by the probe, There are different probes available for UCI hardness testing. They typically cover static loads ranging from 1 N to 98 N.

replica
The surface roughness should not exceed ≈30 % of the penetration depth (Ra ≤ 0.3 × h) with: h[mm]=0.062((Force[N]/Hrdness (HV))^(1/2))
The recommended minimal surface roughness for certain UCI probes that use a Vickers indenter are shown in table annex.
Therefore, at least for the roughness of your piece, it seems that there should be no difference.

Why do not you check ASTM A1038 for further information?

 

MarriolaV,
I'll take your word on the MIC 10 probe options; I guess I have only ever used the standard probe, not purchased one. The key limitation of Microdur is extraneous vibrations from the workpiece influencing the ultrasonic probe. Small boiler tubes and thin shells are problematic.

In the actual Vickers world there is little difference between 5kg and 10kg if you just want to know bulk hardness. Both make too large an indent to capture hardness of small or narrow features such as a heat-affected zone in welded ferritic steels. In the laboratory a 500g or 1kg load is almost universally used for weld evaluations.

Practically, with the MIC 10 in the field I have found that 320 grit is more than adequate for the normal range of constructional steels. However, if I have difficulty delineating the HAZ clearly I will go one or two steps further, but nothing approaching a mirror finish. There is no hard and fast rule, other than etch it and see after each stage.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[weldstan]

From my personal extensive testing, together with that of our inspectors, with the MIC10 and 20 testers, I found the 10 Kg load to give more reproduceable and closer readings than with the 5 Kg load. Comparisons were also more favorable to lab Vickers and Rockwell tests on sample materials.

 

[replica]

Dear all..thank you very much for the comments and information...I find it very useful..