薄壁复杂扩压器部件熔模精密铸造工艺研究

扩压器部件为某型号航空发动机的核心部件,采用ZG1Cr11Ni2WMoV合金无余量精密铸造工艺铸造而成。该部件由内环、外环和空心支板三部分组成,最大直径Φ350 mm,整体壁厚2 mm。通过采用模具分体压制,精密夹具组合定位,熔模拼装组合成型的工艺方案,很好地解决了扩压器部件熔模的成型问题,并简化了模具结构,降低了模具制造成本,铸件尺寸精度可达到CT4级要求。设计采用顶注-侧注相结合的浇注系统,并通过改变局部壁厚,改善凝固条件有效地解决了疏松和缩裂问题。采用较高的型壳温度和适中的浇注温度,浇注出的铸件冶金质量优良,很好地满足了设计和使用要求。

Effect of Magnesium and Cerium Microelement on Microstructures and Mechanical Properties of K465 Nickel-Base Superalloy

0.02%(mass fraction) Mg and 0.02% Ce were added into nickel-base superalloy, K465, in order to study their effect on microstructures and mechanical properties. The results showed that without addition of Mg and Ce, the grain boundaries was flat, the MC carbide precipitate was noncontinuous with particle shape. With 0.02% Mg addition the MC carbide tended to have tiny granular and blocky morphology, while it had a cursive script-like morphology with 0.02% Ce addition. It was also shown that without any addition of Mg and Ce, the room temperature properties, average tensile strength (σb) and yield strength (σ0.2) were 960 and 790 MPa, the creep rupture life under the condition of 1248 K, 230 MPa was 28.1 h. With the addition of 0.02% Mg, the room temperature properties, average tensile strength and yield strength had a certain enhancement, the creep rupture life (1248 K, 230 MPa) was up to 66.7 h. When the Ce addition was 0.02%, average tensile strength and yield strength were up to 1020～1030 MPa and 855～885 MPa, respectively, but the average elongation percentage fell down to 3.0%, only reaching the required value. The most expressive thing was that the creep rupture life (1248 K, 230 MPa) was only 17.25～18.77 h, far below the required value.

K4648合金中空盲管薄壁件无余量精密铸造工艺研究

K4648合金梁为某型号航空发动机尾喷口的核心部件,采用无余量精密铸造工艺铸造而成。该部件为大尺寸中空盲管薄壁件,长度约450mm,管壁厚2.5~3mm。该铸件在铸造过程极易产生疏松和裂纹缺陷,冶金质量难以控制,此外该部件在铸造过程中变形较大,尺寸精度控制困难。针对该部件冶金质量控制及变形等问题,本文对梁部件熔模制备方案、浇注系统设计、浇注工艺及铸件校形工艺等方面进行了系统的研究,研制的K4648合金梁铸件冶金质量优良、尺寸精确。