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针对镍基铸造高温合金K403,在950℃高温下分别进行了5、50和100h的热暴露试验,研究热暴露对K403合金显微组织和室温力学性能的影响。结果表明:K403合金经高温热暴露后,晶内和晶界析出M6C碳化物,γ’相聚集长大且边角发生钝化,随热暴露时间的延长,出现γ’相边角钝化变成圆形或近圆形,部分γ’相发生定向相互连接粗化的现象和趋势;合金的名义屈服强度和抗拉强度随热暴露时间的延长而下降,而塑性则明显提高,导致合金强度下降塑性提高的主要原因之一则是γ’强化相的聚集粗化;热暴露前后,室温拉伸断口均为枝晶组织断裂,热暴露后的试样拉伸断面出现少量沿晶断裂特征和浅而小的韧窝,且存在韧窝的数量随热暴露时间的延长而增多。
Thermal shock tests were carried out at 950 ℃ for 5h, 50h and 100h, respectively. The effects of thermal exposure on the microstructure and mechanical properties at room temperature of K403 alloy were studied. The results show that the M6C carbides are precipitated in the grain boundaries and the grain boundaries after K403 alloy is exposed to high temperature. The γ ’phase grows up and the edges appear passivation. With the increase of heat exposure time, γ’ phase passivation appears Into a round or nearly circular, part of the γ ’orientation occurs cohesion and coarsening phenomena and trends; alloy nominal yield strength and tensile strength decreased with heat exposure time, while the plastic was significantly improved, resulting in alloy strength One of the main reasons for the decrease in ductility is the cohesion and coarsening of the γ ’strengthening phase. Before and after heat exposure, the dendritic structure is fractured at room temperature. A small amount of intergranular fracture is observed on the tensile section of the sample after thermal exposure. Shallow and small dimples, and the presence of dimples increased with the extension of heat exposure time.