If the necessary precautions are not taken, metal hardness test blocks may suffer a problem which totally compromises their validity.
We are talking about the rust forming on test surface, one of the many chemical reactions that most closely concern metals.
We want to specify that each hardness test – Brinell, Rockwell or Vickers – requires a proportional and proportionate surface preparation. Therefore, generally speaking we can take into consideration all those external stresses that modify the degree of superficial adequacy of the test sample.
However, rust is definitely one of the most common problems that occur, and for this reason it is annoying to manage, although as we will see it is easy to prevent.
Keep in mind that ferrous metals are subject to oxidative processes that generate corrosive phenomena if they are not properly protected.
As you may know, these phenomena cause a gradual degradation of the material, which results in an impairment of its properties.
This is not exactly the best for those instruments (i.e., hardness test blocks) which are used to verify the accuracy of hardness values detected by the instrument!
It is therefore good to know how this process takes place. Only the presence of water and oxygen can activate the process.
To be specific, the higher the electrical conductivity of the aqueous solution is, the faster ferrous material corrosion takes place.
This explains why, in the field of hardness testing, the main cause of rust forming is precisely the sweat released by the operator who handles metal test blocks.
You wouldn’t say that, would you?
Following these basic rules will help “extending test blocks lives” and will guarantee their effectiveness when verifying the accuracy of hardness values detected by the instrument.
Because without a hardness test block in good condition, you can never certify the quality of the test results performed through calibration or calibration.
And if you realize that your hardness test block is consumed because its calibration certificate is expired – yes, unfortunately they have a precise validity period, but don’t worry, we will talk about it in the next article – or you just have to renew your range