This part of ISO 6508 specifies the method for Rockwell and Rockwell superficial hardness tests (scales and field of application according to Table 1) for metallic materials. Attention is drawn to the fact that, in this part of ISO 6508, the use of hardmetal for ball indenters is considered to be the standard type of Rockwell indenter ball. Steel indenter balls may be continued to be used if specified in a product specification, or by special agreement. NOTE 1 Attention is drawn to the fact that results obtained with hardmetal balls can be significantly different than when using a steel ball. For specific materials and/or products, other specific International Standards apply (for instance ISO 3738-1 and ISO 4498-1). NOTE 2 For certain materials, the fields of application may be narrower than those indicated.