ZL114A导弹舱体低压铸造工艺与组织性能研究

Research on Low-Pressure Casting Process and Microstructure Properties of ZL114A Missile Segment

采用Pro-CAST仿真计算软件对ZL114A导弹舱体充型流动场、凝固温度场与疏松分布进行了计算分析,充型和凝固总时长分别为9.24 s与2 788.54 s,提高浇注温度和充型增压压力至720℃与15 kPa后,改善了合金熔体的成形流动性能与压力补缩效果,疏松分布显著减少。附铸试样T6态平均抗拉强度、屈服强度、伸长率与弹性模量分别为351 MPa、284 MPa、10.0%与70.4 GPa,本体试样平均抗拉强度、屈服强度、伸长率与布氏硬度分别为343 MPa、280 MPa、8.4%与HBS116,对应离散系数CV分别为1.5%、3.1%、5.4%与3.5%,径向和高向凝固收缩率调整为1.05%与0.90%后,导弹舱体内腔尺寸精度达到HB 6103—2004 CT8级。铸态组织主要由α-Al基体、(α-Al+Si)共晶体、Mg_(2)Si相与Al_(3)Ti相等组成,顶端区域、中部区域与底部区域α-Al基体平均晶粒直径各为96.8μm、112.9μm与117.6μm,T6热处理后铸态板边状与多边块状共晶硅相形貌转变为球状或短粗棒条状,硅相长宽比由11.1降至2.0,断口表面可观察到大量的微观韧窝,材料断裂机制为韧窝断裂。

Pro-CAST simulation and calculation software was used to calculate and analyze the ZL114A missile segment filling flow field, solidification temperature field and shrinkage distribution. In addition, 15 kPa pouring temperatures and 720 ℃ melting fluidity improved melting fluidity and shrinkage compensation, and reduced loosening distribution. The average tensile strength, yield strength, elongation and modulus of elasticity of the attached casting specimens in T6 state were 351 MPa, 284 MPa, 10.0% and 70.4 GPa respectively, and the average tensile strength, yield strength, elongation, and Brinell hardness of the body specimens were 343 MPa, 280 MPa, 8.4% and HBS116, corresponding to the coefficient of discretization CV of 1.5%. After adjusting the radial and high solidification shrinkage to 1.05% and 0.90%, respectively, the dimensional accuracy of the missile segment reached HB 6103-2004 CT8. The as-cast microstructure consisted of primary α-Al matrix, α-Al+Si eutectic, Mg_(2)Si phase, and Al_(3)Ti phase, among others. The average grain diameters of the α-Al matrix in the top, middle, and bottom regions were 96.8 μm, 112.9μm and 117.6 μm, respectively,and the morphology of as-cast eutectic silicon phases of the plate edge and polygonal block was transformed into a spherical shape or a short and thick bar after the T6 heat treatment. The aspect ratio of the silicon phase decreased from 11.1 to 2.0, and numbers of microscopic tough nets were observed on the fracture surface,indicating that the material fracture mechanism was tough nest fracture.