Can you guide me about this topic?
I have a sample with 180 HV (HV0.3), which consists of coarse and fine pits of different depths, and I want to check local hard zones possibility by measuring the microhardness.
If you intend to measure the hardness of materials in the field of mechanical engineering, it can be determined by Rockwell, Brinell, Vickers methods.
Depending in the size and depth of your pits you can use micro- or nanoindentation to make local hardness measurements. in nanoindentation the lateral resolution of hardness can be in the range of 1 µm. - You have to look for the aspect ratio of you pit, since the typical indentors for testing have a rather wide opening angle. So you have to take care, that you don't touch the walls of the pit during indentation. - In principle also hardness mapping is possible.
To measure the microhardness of the surface, a sample of that material should be prepared. I do not recommend measuring the microhardness of rough surfaces.
A sample is prepared from that material to measure the microhardness. Its surface becomes precise. In this case, the correct result is obtained.
Kirsten Ingolf Schiffmann
Thank you for your good answer, and of course, if you have any information about the following, please let me know:
1- Do I remove the LHZ by sandpaper 2000 and above 2000 or not?
Because shallow pits may be lost with this sanding.
2- Is this assumption correct that at the end of the pit, which does not contact the free surface and after sanding, it reaches the free surface, the hardness value is higher and it causes us to consider these areas as LHZ by mistake?
Maryam
If you have prepared the specimen for metallographic examination, then use the same specimen to determine the microhardness of the hard phase in the specimen. Make sure to take 4 or 5 readings to get the average hardness of the hard phase and then convert it into Brinell or Rockwell ' A, B or C ' scale.
Dr. K
Hello. A sample is prepared to measure the microhardness of the surface of materials. When measuring the microhardness of rough surfaces, no traces of the deforming element are visible. Therefore, I believe that to evaluate microhardness, a sample should be prepared with precise surface treatment. Then coatings are applied to its surface. After this, the sample is machined at an angle. This rule is used to evaluate the change in coating hardness with depth.
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