A thickness debit effect characterization parameter for creep rupture behaviors of nickel-based single crystal superalloys

Abstract

Creep rupture tests were conducted on 67 thin-walled DD6 specimens, with thicknesses ranging from 0.35 mm to 1.50 mm, at temperatures of 760 °C, 850 °C, 980 °C, and 1100 °C, revealing a log-linear relationship between rupture lifetimes and specimen thicknesses. Micro-CT observations identified an inhomogeneous distribution of creep micropores around dendrites as a contributing factor to the thickness debit effect. Based on the reliability mathematical method, a possible explanation was proposed for the parabolic law relationship between rupture times and specimen thicknesses. In addition, a thickness debit characterization parameter (TDP) was derived to quantify the trend of creep property degradation as thickness decreases. The TDP equation effectively predicted the creep rupture lifetimes of DD6 thin-walled specimens mostly within a scatter band factor of 2.

Keywords

• Nickel-based single crystal superalloy
• Creep rupture
• Thickness debit effect
• Crystal orientations
• Evaluation parameter
• Creep lifetime prediction