Tag Archives: metric grades
A fastener’s strength is determined by two primary factors: 1) the material it is made from, especially the percentage of hardening carbon in the steel, and 2) the process used to create it – usually heat treatments such as tempering, galvanizing, annealing, and quenching. Treating steel fasteners to harden them necessarily reduces their ductility. Bolts, nuts, and screws can be made to fulfill tasks that require specific strengths and ductility, and identifying these properties aids contractors and manufacturers in selectig the right fastener for the job.
Metric fasteners adhere to strength ratings, or Property Classes, mandated by the International Standards Organization (ISO). Imperial, or SAE fasteners’ ratings, or Grades, are assigned by the American Society for Testing Materials (ASTM). Grades and classes are denoted by markings on the heads of externally threaded hardware and the sides or faces of internally threaded parts: Continue reading