High-temperature testing in a Charpy impact pendulum using in-situ Joule heating of the specimen

摘要

In this paper, an innovative approach to high-temperature testing of subsize Charpy V notched specimens is introduced. The design concept is to heat the specimen on the specimen piece supports up to the moment of impact by flowing AC electric current through it. This approach allows a very accurate centring of the specimen with respect to the anvils and the control of their temperature up to the moment of impact. The temperature profile measured by using the in-situ heating device on ferritic steel specimen over the notch temperature range of 400°C < T< 750°C is presented. The impact energy was measured at different temperatures going through the eutectoid phase transformation of the ferritic steel specimens, with different carbon composition, to investigate the validity of the instrumented in-situ heating method. The method is particularly appropriate to estimate the ductile brittle transition that occurs at high temperature in some metallic alloy systems. Also, its wide range of specimen heating rate provides new research tools for studying, for example, the intermediate temperature embrittlement of metals and alloys.