Welded pipe surface quenching and tempering heat treatment is usually carried out by induction heating or
flame heating. The main technical parameters are surface hardness, local hardness and effective hardening
layer depth. Hardness testing can use Vickers hardness tester, can also use Rockwell or surface Rockwell
hardness. The choice of test force (scale) is related to the depth of the effective hardened layer and the surface
hardness of the welded pipe. Here involves three hardnesses.
