Qualitest’s UCI portable hardness tester employs the ultrasonic contact impedance method to make comparative, nondestructive measurements of your material samples. This process is much faster and easier than traditional testing methods.
The measurement probe has a 136-degree diamond at its end, also known as a Vickers Diamond. This is depressed into the test sample under a specified load. The change in frequency df is measured and converted into a hardness value HV.
What is Ultrasonic Contact Impedance Hardness Testing?
UCI hardness testing uses ultrasonic contact impedance technology to perform comparative hardness measurements on material samples, which enables high accuracy and efficiency. It is also portable, easier to operate and has mass storage capabilities. It is ideal for weld inspection, and hardness control of metal coatings, as well as small forgings, cast materials, welds, heat-affected zones, ion-nitrided stamping, dies and molds, forms, presses, thin-walled parts, bearings, and tooth flanks.
It electronically evaluates each Vickers test indentation in less than two seconds and displays the result digitally. It can also calculate a material’s modulus of elasticity E or hardness HV by using a conversion formula.
Unlike traditional rockwell, Brinell and Leeb hardness testers, which create large indentations on a sample’s surface, this nondestructive method leaves microscopic indentations on the material. It is also capable of measuring the hardness of objects with thin walls and complex geometries, which are not accessible by traditional hardness testing methods.
How is Ultrasonic Contact Impedance Hardness Testing Measured?
While traditional methods, such as Brinell or Vickers, can damage test samples, non-destructive Ultra Sonic testing does not. This method, also known as the UCI Method or SonoDur, can be performed on all metallic parts regardless of their shape, size, thickness or surface condition.
The measurement probe, with a vibration bar and 136-degree diamond at the end (Vickers indenter), is pushed down onto the material. The UCI hardness tester then electronically evaluates each indentation within a fraction of a second and displays the measured results digitally.
The UCI method compares the relative changes in resonance frequencies and adjusts the measurement result to the Vickers hardness scale according to an adjustment curve. This is achieved by calibrating the hardness tester – which is provided with a SONODUR 3 indenter – on MPA-calibrated forged tool steel hardness reference blocks with different E-modulus. This allows the UCI device to determine accurate and reproducible test results even when the indenter is positioned outside of the ideal test position or if it experiences unfavorable handling (ringing of the component). This significantly reduces measuring errors.
Why is Ultrasonic Contact Impedance Hardness Testing Measured?
UCI is a nondestructive testing method that measures the comparative hardness of materials without any damage to the material surface. The test probe, a vibrating bar with a 136-degree diamond (also known as a Vickers pressure head), is pressed against the material and the change df in the frequency f of the resonator is measured. The hardness value HV is calculated from this change using a conversion formula, which includes values for the modulus of elasticity E and the cross-contraction ratio.
Unlike the Rockwell, Brinell and Leeb methods, which cause material deformation during testing, UCI is a nondestructive measurement technique. Its immediate acquisition of hardness values in forward gear also prevents operator error and ensures accurate measurements even for a wide range of material types. This enables a direct comparison with the standardized classic Vickers scale and conversions to all other hardness scales in real-time. This makes it a good choice for weld inspection, quality control in production and for products with thin-walled structures or complex shapes and positions.
What are the Advantages of Ultrasonic Contact Impedance Hardness Testing?
The UCI hardness tester is a non-destructive testing method for metals and alloys that does not damage the work piece. It is also much lighter and more compact than a Leeb probe and can be used in areas where the indentation size and depth are limited or in applications that require a thin wall, complex object shape or surface-hardened layers (such as carburizing, chrome and nitriding).
The measurement probe, which has a diamond-shaped tip similar to a Vickers impact tool, creates the vibration during the test by pushing down on the material – either manually or using a motor depending on your tester model. The measured values are displayed digitally and can be saved and compared right within the instrument.
The SONODUR 3 can be calibrated to a single specimen of known hardness, for plus/minus testing, or it can be calibrated to a range of hardness levels from 2 samples. It features standard calibration fields for steel, stainless steel and non-ferrous materials as well as several user definable fields in Rockwell C, Brinell and Vickers.