Abstract:
Using an Ernest Fullam tensile stage, the surface deformation of advanced alloys (titanium-, cobalt-, and nickel-based) have been characterized in-situ during tensile and tensile-creep experiments at temperatures up to 760oC and stresses up to 1200MPa. Electron backscattered diffraction (EBSD) observations both before and after deformation proved to be useful for determining what type of grain boundaries have deformed and in particular cracked. However, in-situ EBSD orientation mapping can be more useful for understanding how grains and grain boundaries deform and when and where damage nucleation occurs. With this intent a technique has been developed to acquire EBSD orientation maps in-situ during tensile-creep deformation at temperatures as high as 760oC. The EBSD orientation maps were acquired over an approximately 200µmx200µm area using a step size of 0.5µm in 20 minutes (140,000 points were acquired with a speed of approximately 150 points per second). The amount of displacement measured by the testing assembly during this 20 minute period was typically 7µm, and this small drift did not significantly disturb the orientation mapping accuracy. Details and limitations of this testing technique and the results obtained on an advanced structural alloy are described in detail.

Citation: C. Boehlert, "In-situ Tensile-Creep Testing of Structural Alloys," Michigan State University. MaterialsTechnology@TMS 2008.