半固态等温热处理对K4169合金组织和性能的影响

Effects of Isothermal Heat-treatment on Microstructure Evolution and Mechanical Properties of K4169 Super-alloy in Semi-solid State

研究了等温热处理温度和保温时间等工艺参数对K4169高温合金半固态组织演变和力学性能的影响。结果表明,半固态等温热处理可以将K4169高温合金铸态组织中的枝晶转变为球形晶粒组织,在升温过程中晶界处部分γ相发生溶解,随着温度的升高,γ+γ′共晶相开始熔化,初生γ相在等温处理中逐渐演变为球状;等温温度越高,半固态重熔和初生γ相的演变过程越快,等温温度过高或保温时间过长,试样易发生变形且球形晶粒趋于长大;K4169高温合金半固态等温热处理时的最佳热处理工艺为加热温度1310℃左右,保温时间为90～120min,或加热温度1320℃左右,保温时间为45～60min;半固态等温热处理对合金压缩强度的影响与合金的组织形态有关,半固态K4169高温合金的硬度与铸态相比有所降低。

The microstructure evolution and mechanical properties of K4169 super-alloy during semi-solid isothermal heat treatment are studied. The results show that the semi-solid isothermal heat-treatment can turn the dendritic structure of K4169 super-alloy into spheroids. The process is as following： during the increasing of temperature, the partial γ phase at grain interface of eutectic structure is dissolved; then with the further increasing of temperature, the γ＋γ＇ phase begin to remelt successively and the y phase gradually evolves into spheroidal shape during the holding. The higher the isothermal temperature, the faster the semi-solid remelting and the γ phase evolution process. When the isothermal temperature is much higher or the holding time is much longer, the samples are susceptible to deformation and the spheroidal structure is also susceptible to grow up. Holding temperature 1310℃, holding time 90-120min or holding temperature 1320℃, holding time 45-60min. are the best isothermal heat-treatment of k4169 super-alloy. The effects of isothermal heat-treatment on compress strength of K4169 super-alloy relate to the form of the microstructure. The hardness of K4169 super-alloy in semi-solid state is lower than the casting＇s.