一次时效处理对GH141焊后应力变化及碳化物分布的影响

Effects of primary aging on stress variation and carbide distribution of GH141 superalloy after welding

利用Gleeble-3500热模拟实验机模拟了GH141高温合金焊接及焊后热处理过程,固溶处理后采用1020℃~875℃区间6组不同温度以及300 s^1800 s区间5组不同时间分别进行一次时效,然后在相同工艺下进行二次时效,研究一次时效温度和时间对整个热处理过程应力变化及碳化物分布的影响。结果表明,一次时效温度对应力变化趋势影响较大,温度越低,开始时应力越高,且在1020、960与875℃三个温度时应力呈下降趋势,940℃时应力先上升后下降,980℃与900℃时应力呈上升趋势,总体来说在960℃处理时应力值较低且平稳,且960℃时碳化物分布均匀并呈点链状,对强化晶界有利;不同一次时效时间下应力变化趋势基本一致,但在1200 s后应力出现回弹现象,且处理时间越长,二次时效时应力峰值出现时间越早。

Processes of welding and post-heat treatment, which was solution treatment, primary aging and secondary aging, for GH141 superalloy were simulated on a Gleeble-3500 thermo-mechanical simulator. The aging process were carried out at different temperatures in the range of 1020 ℃-875 ℃ with different time of 300 s-1800 s after solution heat treatment. The effects of primary aging temperature and time on the welding stress in the heat treatment processes and carbide distribution in the alloy were investigated. The results indicate that the temperature of primary aging has significant influence on the variation of the stress in the early primary aging stage, the lower aging temperature gives the higher stress. At the aging temperature of 1020 ℃ , 960 ℃ and 875 ℃ , the stress shows decline trend, the stress first increases and then decreases at 940 ℃ , and the stress increases at 980 ℃ and 900 ℃ as the aging time increases. In general, the lower and steady stress is observed at the primary aging temperature of 960 ℃ , at which the distribution of point-chain shaped carbides is uniform and is favorable to strengthening the grain boundary. The stress variation trends are basically identical under different primary aging time, but after 1200 s the stress exhibits rebound phenomenon, and the longer the primary aging time is, the sooner the peak stress appeares for the secondary aging treatment.