Discussion on Practicability and Validity of Rockwell Hardness Test Standards of GB/T 230.1-2009 and GB/T 230.2-2012

The problems existing in the practicability and validity of Rockwell hardness test standards of GB/T 230.1-2009 and GB/T 230.2-2012 were discussed. It is pointed out that direct verification of Rockwell hardness machines to ensure hardness results correct is impracticable for industry laboratories. Another problem is that the control method with permissible bias Rockwell unit in GB/T 230.2-2012 will be invalidity for some laboratories which require better accuracy. Using a large number of reference hardness blocks without aging effect and with the same reference hardness values to monitor the long-term stability of hardness machines in full life circle, combined with indirect verification of the professional measurement department every year, is a valid method for tracing and accuracy. With the daily verification data of these reference hardness blocks to draw statistical process control chart or tendency chart can show the departure of the hardness machines better and guaranteed the accuracy of the hardness machines better than with permissible bias Rockwell unit in GB/T 230.2-2012 for hardness test results.