Effect of preweld conditions on the strain ageing cracking susceptibility of IN939 superalloys heat affected zone
Jilin Xie, Changhao Geng, Jiazhe Song, Yuhua Chen, Shanlin Wang, Peng He
Abstract
The evolutionary behavior of precipitated phases is a key determinant of strain aging cracking sensitivity in superalloys. In multi-component superalloys, these behaviors are influenced by pre-weld conditions and heat input. The strain aging cracking (SAC) sensitivity of the heat affected zone (HAZ) of IN-939 superalloy with various pre-weld heat treatment conditions was studied. The SAC sensitivity of the IN-939 superalloy samples was evaluated through the strain-to-fracture test (STF) by monitoring the ductility and fracture time during the test. The SAC sensitivity influencing factors including microstructure evolution, phase precipitation behavior of IN-939 superalloys were analyzed by electron probe micro analyzer (EPMA)、in-situ and exit-situ TEM test. The results showed that the SAC sensitivity of overaged IN-939 superalloys is smaller than that of the solid-solution condition showing larger ductility and longer fracture time during the STF test. The fast precipitation of γ′ phase in the IN-939 superalloy HAZ during the STF test is responsible for the large SAC sensitivity of the solid-solution condition. The SAC sensitivity temperature range is well consistent with the fast precipitation temperature of γ′ phase.