Effect of contact angle on contact morphology and Vickers hardness measurement in instrumented indentation testing

• We derive general contact-depth function for Vickers indenter.
• We investigate effect of material properties and indenter angle on materials pileup.
• We propose a novel way to determine contact-depth function and Vickers hardness.

We derive a general contact-depth function for the Vickers indenter by modifying a scaling relation between yield strain and indentation depth ratio, which is comprised of indenter angle, plastic constraint factor, and indentation depth ratio. The validity of this function is demonstrated by using various indenters of different angles. A method for calibrating the actual contact area of an imperfectly shaped Vickers indenter is suggested that yields a better evaluation of Vickers hardness in the instrumented indentation test.