The Effect of Primary Axis and Low Angle Boundary Misorientation on CMSX-10K Mechanical Properties

Abstract

The U. S. Department of Energy’s Advanced Turbine Systems (ATS) program supports the development of high efficiency gas turbines for industrial and power generation applications. As part of this program, CMSX-10K, a third generation single crystal Ni-base superalloy, is being considered for use in turbine blade applications in an ATS engine. In support of the design and casting process development of CMSX-10K, assessment of component tolerance to casting defects was performed. Single crystal specimens with primary axis orientation between 4 and 26 degrees and bicrystal specimens with low angle boundaries (LABs) having between 0 and 18 degrees of misorientation were used. The effects of primary axis misorientation and LABs on critical mechanical properties were evaluated. Primary axis misorientation of greater than 15 degrees reduced tensile and high-cycle fatigue properties. Similarly, stress rupture properties were reduced for primary axis misorientation of greater than 20 degrees. LABs having greater than 10 degrees of misorientation caused significantly reduced stress rupture life. LABs having greater than 12 degrees of misorientation also resulted in reduced tensile and high-cycle fatigue properties.