On the Errors of Rockwell Hardness Number : 3rd Report, The Effect of the Error of Steel Ball Diameter

On the error introduced into Rockwell hardness numbers by the error of steel ball diameters, this paper reports the results of experiment and the caluculated results from Meyer's law. Results obtained by observation and theoretical calculation respectively coincided well with each other. Accordingly, the errors caused by the errors of total load W2 kg, preliminary load W1 kg and diameter D mm are shown as follows : [numerical formula].