Effects of Temperature on Failure Modes for a Nickel-Base Disk Superalloy

Increasing service temperatures of gas turbine engines can improve performance and efficiency. Therefore, advanced alloys are being considered for higher-temperature applications than previously encountered. To support these higher-temperature applications, failure mode assessments on specimens tested in laboratory test machines can help in understanding prospective failure scenarios. The effects of temperature on tensile, creep, low-cycle fatigue, and fatigue crack growth failure modes were evaluated for an advanced powder metallurgy disk superalloy ME3. Conventional tests were performed at temperatures up to 815 °C on specimens extracted from supersolvus heat treated disks. The failure modes were compared with increasing temperature for each test type. Fractographic evaluations indicate the failure modes were shifted by increasing temperature, and eventually became environment-assisted, surface crack initiated failures.