Fastener mechanical tests include proof load of bolts and nuts, wedge tests for head soundness, tensile test (on full size or machined samples), proof/yield stress, total elongation, reduction in area and standard or micro hardness (surface and core).
We also perform torque tests (not UKAS accredited). The 24-hour hardness test including heat treatment (the heat treatment is not UKAS accredited) on nuts to ASTM A194 is routinely performed.
Metallurgical tests on fasteners are increasingly more important and include decarburisation/carburisation tests, microstructural assessment including phase analysis, banding, segregation and the use of micro hardness to determine phase hardness e.g. martensite, ferrite, bainite etc.
Longitudinal sectioning and macro etching is carried out to delineate forging flow lines at the bolt head-shank interface and helps reveal structural integrity along the bolt length from head to shank end.
Chemical analysis of fasteners and/or starting material is clearly of fundamental importance-if the start material or semi-finished fastener bears the right chemistry, there is every chance that optimum subsequent downstream processing will result in specification compliance.
Elevated temperate tensile testing and fastener surface testing can be of great importance depending on the end use application. We can perform elevated temperature tensile testing on machined fastener feed stock or machined fasteners to ASTM E21 and BS EN SO 6892-2. Any inorganic coating (e.g. plating, galvanising, sherardising) or organic coating (e.g. painting, plastic coating, Xylan, Dacromet coating) can be salt spray tested to ASTM B117/BS EN SO 9277.
We can also offer plating/coating thickness measuring to BS EN SO 1463 and coating mass determination to BS EN 10346 and 10152.
Finally, we can test fastener surfaces for the presence of hexavalent chromium (Cr6/CrVI) on suspect or designed chromate treated surfaces.