3. Characteristics of the case-hardening or carbonitriding layer

3.1 Surface hardness

Workshop tests are usually carried out using the Rocwell C or Rockwell A method, for shallower depths, or even the HR45N or HR15N surface Rockwell method. As the reliability of these low-load measurements is relative, it is advisable to confirm the validity of the measurements by Vickers testing. The choice of Vickers test load must take into account the depth and level of hardness.

Generally, hardness is expressed at a minimum value, plus a maximum tolerated value, e.g. 680 HV + 150 HV or 680 to 830 HV. Recommended hardness dispersion values are given in the CETIM document drawn up in collaboration with the industry (table 3 ).