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详细研究了紧固件用高温合金GH4738在不同温度和初应力,及不同热处理制度下的应力松弛行为。研究表明:应力松弛的两个阶段之间存在一个槛应力σ’_0,低于此槛应力σ’_0时,塑性应变速率快速下降。随着温度的升高,GH4738合金的松弛稳定性下降,应力松弛速率加快,松弛极限降低。随着初应力的提高,松弛第1阶段松弛速率加快,松弛极限有所增大。不同的固溶温度和稳定化热处理工艺主要影响了合金松弛过程的第2阶段,对其槛应力及松弛稳定性均无明显影响。
The stress relaxation behavior of high temperature superalloy GH4738 for fasteners under different temperatures and initial stresses and different heat treatment systems was studied in detail. The results show that there is a stress σ’_0 between the two phases of stress relaxation, and the plastic strain rate decreases rapidly below this stress σ’_0. With the increase of temperature, the relaxation stability of GH4738 alloy decreases, the rate of stress relaxation increases and the relaxation limit decreases. With the increase of initial stress, the relaxation rate in the first stage of relaxation increased and the relaxation limit increased. Different solid solution temperature and stabilization heat treatment process mainly affect the second phase of the alloy relaxation process, and have no significant effect on the threshold stress and relaxation stability.