One of the key functions of the Test House at Keighley Laboratories is to test materials and components to establish their mechanical properties and structures.
Impact tests are used to measure the toughness/brittleness of a material and its capacity to resist mechanical shock. The two main types of testing are CHARPY and IZOD testing, which are undertaken to European and American standards. Izod testing is always carried out at room temperature, whereas Charpy testing can be carried out at temperatures between –196°C and +200°C.
Tensile and Compression Load Testing
A test piece of known cross-section is put in tension or compressed until either a proof load is achieved (nuts & bolts etc.), or failure occurs. These tests can be undertaken at ambient, sub-ambient and elevated temperatures, ranging from -100°C to +750°C. Stress strain and load deflection curves are produced for different materials for loads from a few Newtons up to 1100kN.
The hardness of a material is its resistance to indentation by a hardened steel/tungsten ball or diamond indentor. The following types of hardness testing are carried out at Keighley Laboratories; BRINELL (in house and on site), ROCKWELL (most scales), VICKERS (both micro and macro – manual or fully automatic) and KNOOP.
Metallography consists of preparing a piece of material by grinding, polishing and etching and subsequently examining it under magnification.
This process allows the metallurgist to determine certain characteristics regarding the material, such as grain structure, case depth, Alpha Case, Alloy Depletion, Deleterious Phase Check, Volume fraction, percentage cavitation, quality of heat treatment, weld quality and coating/plating thickness etc.
Macro examinations (up to x 10 magnification) and Micro examinations (up to x 1000 magnification) are undertaken on equipment including projection and stereo binocular microscopes, all employing digital image capture techniques (image analysis is also available).
This function provides quick and accurate evaluation of microstructures,demonstrates linear measurements with certainty and measures grain size, phase count, % cavitation and volume fraction.
Specimen and component fatigue testing at ambient temperatures.
Maximum test load capacity 150kN.
Operating frequency 60-180Hz, dependent on stiffness of specimen being tested (resonant frequency).
Digital equipment to control and monitor functions.
Fatigue occurs when a material is subjected to repeated loading and unloading. If the loads are above a certain threshold, cracks will begin to form at the surface. Eventually a crack will reach a critical size, and the structure will suddenly fracture.
Digital equipment is used to control and monitor the test functions.
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