Most people do this biggest mistake- they try to test a surface without smoothing it out, cleaning the grease or removing the paint from it. The hardness testing is related to surface testing- anything that gets between the Non-destructive testing equipment and the metal is going to influence the hardness measurement and that leads to notable measurement deviations (in most of the worst scenario).
There are certain things regarding the test object, surface preparation and performance of the measurement need to be observed to get reliable measurement results-
- You can perform hardness testing using portable equipment on objects with distinct shapes. The hardness tester can be put into vertical position to the test surface. You need to ensure that the surface of the component should be flat and smooth.
- The test area should be prepared in such way that changes to the surface made by heating or cold deformation remain restricted to a minimal. You must remove foreign objects, scale, and other surface imperfections and make the surface free from lubricants.
If the surface remains rough, it has a significant effect on the repeatability of the measurement.
You must remove all foreign particles, like rust and scale from the surface initially. Later, you can think about grounding and polishing of that surface. You can use tools like flap wheel grinders with P240, P120, and P320. Every grinding step is done perpendicular to the previous one. You can stop grinding when all the marks from the previous step have been ground away.
Relying on the test application, distinct available probes and hardness tests can be used. You must be able to pick the right NDT testing equipment or instrument that should be based on the surface preparation. The hardness test involves general rule, i.e. the better surface condition, the more precise and reproducible the measurement results.
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Quality assurance of construction materials is vital to construct strong, durable buildings and cost effective structures. While taking an architectural project, you must select the building materials to fulfill the functions that you expected from them.