A novel laser-based high temperature mechanical property characterization method

In this work, a novel method was reduced to practice using a 50-W CO2 continuous wave (CW) laser to bulk heat metal specimens for uniaxial tensile tests in a controlled pressure chamber. The ability to rapidly heat a localized area on the specimen gauge length removes many of the issues and limitations that other high temperature testing methods inherently experience. Graphite coated aluminum and copper dog bone specimens were tested. Digital Image Correlation (DIC) and infrared (IR) thermography are employed to determine strain and temperature distributions in the specimens under test, while a thermocouple was used to measure the temperature at the back of the specimen. Three tests for each metal were performed: one at room temperature (for benchmark) and two at a higher temperature. A COMSOL model was prepared, and the laser deposition was simulated by using the Beer Lambert equation coupled to the energy eq. A MAX-phase specimen is also tested for proving the method for very high temperatures (>1800 °C). This method is capable of generating large thermal gradients (~1000 °C/mm) through the specimen thickness for simulating the thermal shock that materials may experience under normal operating conditions. A prescribed or more homogeneous though-thickness temperature gradient could also be achieved via beam splitting and heating from the top and bottom of the specimen concurrently. This technique is a viable alternative to other existing high temperature methods (i.e., single and multizone furnaces, induction, and joule heating), but with the added benefits of free access and viewing of the specimen for enabling additional non-contact measurements. • Developed a novel method for laser-based high-temperature tensile testing. • Achieved precise thermal gradients using a 50 W CO2 laser in vacuum conditions. • Demonstrated localized heating for Cu, Al, and MAX-phase materials. • Enhanced temperature and strain measurements using IR thermography and DIC. • Validated method as a viable alternative to furnaces, induction, and joule heating.