A quick measuring method for yield temperatures of materials under constant prestress at ultra-high temperatures

A new method for the rapid measurement of the yield temperatures of the material subjected to constant prestress at ultra-high temperatures was proposed, combining electric heating with non-contact image measurement technology. In this method, the yield temperature could be determined with a small number of thermal cycles in which the peak temperature increases with an increase in the number of thermal cycles, and in each cycle, the material is heated to a prescribed peak temperature and then cooled. There are two pairs of tiny sharp protrusions in the central part of the specimen. During the test, the surface optical image is recorded and analyzed with code Halcon to determine the temperature and elongation of the specimen. The time of each test is less than 20 min, so the influence of over-heating on the properties and microstructure of the material can be avoided. It is worth noting that the developed method can effectively reduce the test time and cost without breaking the specimen, and should have great potential in testing for the mechanical properties of materials at ultra-high temperatures.