Non-destructive testing (NDT) material testers are devices, machines and equipment that are used to determine residual stress, alloy type, hardness, microstructure, elasticity, heat treatment and other material conditions without permanently altering or destroying the material being examined. NDT material testers include a variety of instruments and a range of technologies. Examples include ultrasonic techniques, laser shearography and holographic interferometry, as well as many magnetic, thermoelectric, and electromagnetic methods. Some non-destructive testing (NDT) material testers can be mounted on a rack, in a cabinet, or on a printed circuit board (PCB). Other devices are designed to be held by hand or placed on a benchtop. Complete NDT material testing monitoring systems can continuously detect or measure flaws, thickness, or corrosion in production line, plant, production, or field applications.

Non-destructive testing (NDT) material testers use several technologies. Acoustic emission instruments monitor conditions and detect changes in mechanical, electrical, and process systems. For example, ultrasonic (UT) noise detectors use the pulse-echo technique to transmit and retrieve beams of high frequency acoustic energy. By contrast, infrared (IR) NDT material testers transmit or reflect radiation in order to determine absorption levels. X-ray diffraction and X-ray fluorescence are other non-destructive, radiographic test methods. Eddy current instruments induce detectable eddy currents in conductive materials, providing information for applications such as flaw detection, thickness determination, weld inspection, conductivity measurement, alloy sorting, and heat treatment verification. Optical-based non-destructive testing (NDT) material testers perform laser shearography or holographic interferometry to detect flaws or measure residual stress. Other magnetic, magneto-optical, and electromagnetic testing technologies are also used.

Properties Measured

Non-destructive testing (NDT) material testers can measure a variety of properties. Ultrasonic (UT) NDT material testers with velocity measurement capabilities can measure changes to a material’s elastic modulus, the ratio of stress (force per unit area) to corresponding strain (deformation). Ultrasonic techniques can also detect microstructural variations in materials such as cast iron. To measure hardness, the ultrasonic contact impedance method and the rebound hardness test are often used. In specific steels, tensile strength can be inferred from hardness values. Residual stress is commonly measured with X-ray diffraction, magnetic, or Barkhausen noise techniques. Resonant ultrasonic spectroscopy can also provide an indication of material strength. Some non-destructive testing (NDT) material testers measure the conductivity or resistivity of materials. Others measure density variations by radiation absorption or sound wave attenuation. Instruments that sort alloys based on chemical composition are also available.

Features

NDT material testers are available with many features. Some non-destructive testing (NDT) material testers can display metric units such as millimeters (mm) or English units such as inches (in). Other devices include magnetic induction probes that are suitable for a variety of scientific measurement, navigation, and industrial applications. NDT material testers with data logging capabilities can store and retrieve data for future processing. Non-destructive testing (NDT) material testers with sorting gates or an alarm mode notify users when a reading is outside a range of specified values.