The hardness of a material is a defined quantity having many scales and being dependent on the way the test is performed. In order to avoid the creation of a new practice involving a new hardness scale, the UCI method converts into common hardness values, for example, HV, HRC, etc.

The UCI hardness test is a superficial determination, only measuring the hardness condition of the surface contacted. The results generated at a specific location do not represent the part at any other surface location and yield no information about the material at subsurface locations.

The UCI hardness test may be used on large or small components at various locations. It can be used to make hardness measurements on positions difficult to access, such as tooth flanks or roots of gears.

1.1 This practice covers the determination of comparative hardness values by applying the Ultrasonic Contact Impedance Method (UCI Method).

1.2 The measured values are stated in SI units, which are regarded as standard. Equivalent inch-pound values, when given, are in parentheses and may be approximate.

1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.