Effects of Various Errors on the Superficial Rockwell Hardness Reading : 2nd Report, Tests Using the Diamond Indenter

Abstract

On the superficial Rockwell hardness test which is becoming more popular, the authors have reported the effect of various errors on the T scale hardness reading in the first report. In this report, the effects of errors in the preliminary load W₁ kg, the total load W₂ kg, the tip radius R mm of the diamond indenter and the included angle θ rad. on the N scale hardness reading H_RN are analytically clarified by using the extended Meyer's law and the law of similarity. As an example, the following equation is obtained for a medium hardness specimen (30≤H_R15N≤70), ΔH_R30N={139.2-9.486×10^-3(100-H_R30N)²}ΔR+1.734(65.40-H_R30N)Δθ+0.6656×10^-3(100-H_R30N)²ΔW₁-2.527×10^-2(100-H_R30N)ΔW₂ A good agreement is observed between the analytical results and the experimental ones. In addition, the authors' proposal for establishing a tentative JIS (Japanese Industrial Standard) is made.