Measurement uncertainty
Test and measurement uncertainty indicates how much measurement results can vary in hardness tests. It accounts for factors such as the machine, the operator, and the specimen.
Physical-Chemical Mechanism of Action
The test and measurement uncertainty describes the maximum deviation of hardness readings from an ideal average value. This uncertainty arises from various sources such as machine inaccuracy, human error in performing the test, or irregular properties of the specimen being tested.
Metallurgical Relevance & Welding Risks
High test and measurement uncertainty can lead to incorrect hardness classifications. This can cause the material to be deemed non-conforming when it actually exceeds the specified hardness limits, or vice versa. This can lead to safety issues or unnecessary costs in the case of rejections.
Workshop Practice & Instructions
To minimize test and measurement uncertainty:
• Calibrate the hardness tester regularly (e.g., every 6 months).
• The operator should undergo regular training to maintain skills.
• Select specimens that are sufficiently representative of the entire workpiece.
• If necessary, perform an additional hardness test to confirm the results.