型壳保温温度对DD98单晶合金组织和性能的影响

Effect of Mould Holding Temperature on the Microstructure and Mechanical Property of Ni Base Single Crystal Superalloy

研究了不同的型壳保温温度对一种铸造单晶高温合金DD98铸态组织、热处理组织和持久性能的影响。结果表明,随着上下区型壳保温温度的升高,固液界面前沿的温度梯度增大,而糊状区的宽度减小。铸态下,随着上下区型壳保温温度的升高,其一次和二次枝晶间距均减小,枝晶间和枝晶干上的γ′尺寸差别减小,并且枝晶间的γ′形状也逐渐变得规则,合金的显微偏析程度降低。热处理后,高的型壳保温温度可获得尺寸细小的γ′和较少的残留共晶。合金的持久寿命随着型壳保温温度的升高而增加,但相应的持久延伸率降低。

Effect of mould holding temperature on the microstructure and mechanical properties of single crystal superalloy DD98 have been investigated. The results show that with the increase of up/down mould holding temperatures, the temperature gradient increases and the width of mushy zone decreases, the primary and secondary dendritic arm spacings decrease, the shape of γ＇ phase particles tends to be more regular, and the micro segregation decreases. The size of γ＇ phase particles and the amount of remained γ-γ＇ eutectic phase decrease after heat treatment at higher mould holding temperatures. The creep rupture life increases with the increase of mould holding temperature, while the elongation decreases.