Metallurgist, The Greer Steel Co., Dover, Ohio
Pages: 8 Published: Jan 1971
An interlaboratory program was organized by members of the ASTM-ASME Joint Committee on Effect of Temperature on the Properties of Metals, Subcommittee on Test Methods, to determine the consistency of temperature measurement that exists among laboratories conducting elevated temperature testing. An evaluation was made of one phase of the pyrometric practice applied, comparison of the temperature at the center of a tension specimen measured with a common reference thermocouple with the temperature of its surface using the method of thermocouple manufacture and attachment utilized by each participating laboratory. In order to simulate the normal heat losses experienced through conduction during elevated temperature testing, a typical specimen train was included. Additional clad Chromel-Alumel thermocouples, taken from a section of calibrated wire, also were provided for one time use only.
Each of the participating laboratories attached their thermocouples to the specimen and adjusted the temperature controller so that the attached thermocouples indicated exactly 1200 F (922 K). The emf of the common reference thermocouple then was measured using the same reference junction utilized in their normal practice. This procedure was then repeated using the calibrated thermocouples exposed for only one measurement.
The information that has been developed by the seven participating laboratories to date has shown more variation than was expected. The total range of reported temperatures for the common thermocouple was 11 F (6.1 K) and 18 F (10 K) for the single-use thermocouples.
temperature measurement, temperature measuring instruments, high temperature tests, tension tests, thermocouples, thermocouple pyrometers, nickel alloys, nickel-chromium alloys, stainless steels
Paper ID: STP26908S