In Situ Hardness Testing, Near Non-Destructive

To determine if fire-exposed material has suffered any softening or hardening due to microstructural degradation or changes during fire or process upset (which would indicate a need for repair or replacement), hardness is usually measured with a portable hardness tester. I2C inspectors often uses a tool commercially known as a “Telebrineller” hardness tester and GE’s MIC 20 ultrasonic contact impedence hardness tester. The Telebrineller method measures “bulk” hardness of the sample by pushing into the material and measuring the amount of denting at a given pressure.  The resulting measurement includes a volume measurement incorporating the surface and a depth of 2-3 mm below the surface.  Telebrineller measurements can indicate fire damage that extends beyond the surface “skin” of the metal being tested. MIC 20 provides a expedient and precise reading, areas such as heat affected zones, and other small areas are readily tested with no noticeable damage to the part’s surface. Application of either test method must be carefully chosen based on material type and desired result. I2C’s experienced staff has the knowledge to properly apply these techniques where applicable generally in conjunction with material assessment associated with elevated temperature exposure.