Standards Development

Scope

This part of ISO 14577 specifies the instrumented indentation method for testing at elevated temperature for determination of hardness and other materials parameters at temperatures above ambient. Elevated temperature testing is when the test piece and indentation tip are heated above the ambient conditions to a controlled and measured temperature; insulating shielding is used to enclose the hot zone to reduce heating effects so that the majority of the instrumented indentation testing machine is at ambient conditions.

This standard is restricted to test machines that have been traceably calibrated and/or verified according to ISO 14577-2 when operating at temperature to ensure the effects on ambient sensors by the presence of a hot zone are accounted for. This standard covers instrumented indentation testing at elevated temperatures in air, in inert/reducing gaseous environments, or in vacuum.

This standard provides a method for instrumented indentation testing at elevated temperatures with the indenter tip and test piece actively heated with independent feedback control and temperature measurement of the indenter tip. The contact temperature is assigned to be the iso-thermal contact temperature measured by traceably calibrated temperature sensing using a low heat capacity indenter tip. Iso-thermal contact is achieved and verified by detecting then minimising absolute heat flow between tip and test piece when making and breaking indentation contact. The method can achieve low uncertainty in the temperature assigned to the indentation contact and minimises the temperature gradient from contact to the bulk of the test piece that can occur when testing materials with both high and low thermal conductivity.

The scope of this standard does not include:

— Instrumented indentation testing where there is no measurement of the temperature of the indenter tip body itself by a temperature sensor mounted on the indenter tip body.

— Instrumented indentation testing where above ambient temperatures are obtained by placing the entire instrument in a hot box to achieve iso-thermal heating of the whole system. These systems typically only achieve limited elevated temperature.

— Instrumented indentation testing with active heating of the test piece but only passive heating of the indenter, e.g. by proximity to the hot test piece and thermal conduction through the indentation contact, hot gas, or any combination.