All fastener testing at The LAB is performed per ASTM, SAE, MIL, ISO, or other standards. The LAB's technicians and comprehensive quality control program ensure complete, reproducible, accurate results every time. The LAB’s clients have come to expect exceptional customer service, quick turn around and competitive pricing for all their mechanical testing requirements.

Definitions/Supplementary Information on Types of Fastener Testing

• Hardness Testing

  To best determine a material’s strength, ease of machinability and wear resistance, one would conduct a resistance-to-penetration hardness test. Rockwell hardness testing is a commonly used scale for indicating the superficial hardness of a material. It is also valuable in helping to make decisions about treatments and coatings. Superficial Rockwell testing is similar—the difference is that it requires smaller minor and major load values.

• Microhardness Testing

  Microhardness tests a material’s hardness in a similar way to Rockwell, but with a microscopic indentation. This test can provide a hardness value for a very precise location on a part, enabling the detection of variations in hardness from one location to another. All tests offer different load options and many different scales between the three testing options.

• Magnetic Permeability

  A magnetic permeability test measures a material’s ability to become magnetized. When a material is placed in a magnetic field, it interacts with the field in one way or another. If a material is more conductive to the magnetic field, it will have a higher permeability.

• Proof Load Testing

  Proof load testing entails stressing the sample with a quantified load that the sampling must withstand without measurable permanent set. The load used to stress the fastener is specific to the size and grade/property class of the sample.

• Wedge & Axial Tensile Testing

  Axial and wedge tensile testing is done to determine the behavior of materials under axial tensile loading. Axial tests are performed by securing the fastener into the testing machine and then applying force to the fastener by separating the testing apparatus crossheads. The wedge test is also an axial test. The difference is that a wedge is placed under the head during testing to see if the head of the fastener can withstand the added stress of the torque load caused by the wedge. The wedge tensile test is usually done on square or hex head fastener and socket head cap screws.

• Yield Strength

  A yield strength or yield point of a material is the stress point at which a material begins to deform plastically. Any time before the yield point, the material will deform elastically and should regain its original shape when the applied stress is removed. Once the material is stressed beyond the yield point, some portion of the deformation will be permanent and non-reversible.

• Carburization and Decarburization

  Testing for carburization and decarburization surface conditions in metals will determine the amount of carbon in a specimen. When a test is ordered for one of these conditions, both conditions will be apparent and both will be reported. Too much of either condition may adversely affect the safety and performance of the metal. This test method is not intended to address products which are intentionally carburized to achieve specific results. The testing method classifies, measures, and determines the existence of decarburization and carburization in the threaded section of hardened and tempered metals which have been heated to enable fabrication or to alter their mechanical properties.

• Grain Size

  An accurate assessment of grain size in a given metallic sample is used to determine the effectiveness of a specific manufacturing process (e.g., heat treating or tempering). Technicians prepare the sampling by mounting a cross section, polishing it, and etching it. Etching reveals the grain. Once the sample is prepared, there are several procedures a technician can perform to determine the precise grain size of the specimen.

• Micro Examination

  Inspection per SAE AS 7477/SAE AS 7478 includes examinations of flow lines, internal defects, microstructure, grain size per ASTM E112, surface hardening and tread defects.

• Micro Indication Verification Examination

  The Micro Indication Verification Examination (MIVE) verifies defects found in NDT methods which cannot be fully measured by the NDT method. The MIVE will provide 3-dimensional measurements of indications such as thread laps and seams and can change the disposition of an NDT test from failure to passing if the indications are within the tolerances of the specification.

• Digital Imaging

  The LAB technicians record digital images of all indications found in NDT, and all metallographic tests. Reference images are available upon request. Calibrated images are available for an additional charge.

• Ferrite by Pointe Count (ASTM E562)

  This test method is based upon the stereological principle that a grid with a number of regularly arrayed points, when systematically placed over an image of a two-dimensional section through the microstructure, can provide, after a representative number of placements on different fields, an unbiased statistical estimation of the volume fraction of an identifiable constituent or phase.

• Macro-etch (ASTM E340)

  Macroetching provides information on variations in structure, such as grain size, flow lines, columnar structure, dendrites, etc.. Macroetching also reveals the presence of discontinuities and voids, such as seams, laps, porosity, flakes, bursts, extrusion rupture, cracks, etc..

• Inclusion Rating (ASTM E45)

  This test identifies the inclusion content of steel. Inclusions are characterized by size, shape, concentration, and distribution, rather than chemical composition. Although compositions are not identified, the microscopic method places inclusions into one of several composition-related categories—sulfides, oxides, and silicates.