High-temperature tensile and creep tester for wire

Abstract

To provide test facilities for determining the tension and short-time creep properties of small-diameter tungsten wire at high temperatures, special equipment has been designed and built, employing rf (radio frequency) heating as the means of attaining temperatures up to 2600° C.

This paper describes the problems which had to be solved in designing and building the equipment, and gives results to tests made after the equipment was assembled.

The equipment had to meet these requirements: it had to be capable of providing tension and short-time creep data on tungsten wire in sizes from 0.001 in. diam to 0.009 in. at temperatures up to 2600° C, it had to provide an autographic stress-strain curve for the tension tests, the loading rate during tension tests had to be constant, and all of this had to be done in good vacuum.

Basically the equipment consists of a loading frame which supports a calibrated beam-type load dynamometer, a synchronous electric-clock motor for applying the load, rf equipment for attaining the desired temperature, an X-Y recorder for recording stress-strain curves, and a two-color automatic optical pyrometer for measuring the temperature. The test arrangement is mounted on a vacuum base plate under a bell jar. For creep testing, the flexible beam is replaced by a rigid beam, and load is applied by means of dead weights. Creep strain is measured with a cathetometer or Optron.