离心真空吸铸工艺对铸件力学性能的影响

Effect of Centrifugal Counter-Gravity Casting Process on Mechanical Properties of Castings

在自行设计并安装的离心真空吸铸设备上,通过设计熔模铸型,研究了转速对离心真空吸铸ZL114A铝合金试棒力学性能的影响。结果表明:在真空吸铸过程中施加离心力,增强了铸件的凝固补缩能力,而且在离心过程中金属液的对流限制了树枝晶的生长,使铸件显微组织更加均匀,晶粒细化;与普通的真空吸铸相比,离心真空吸铸技术能显著提高试棒的抗拉强度和伸长率。在转速为100 r/min时,试棒的抗拉强度最高达373.37 MPa,伸长率最大达9.99%,比同一位置真空吸铸试棒分别增加了7%和44%;当转速增加到200 r/min时,过大的转速破坏了金属液的自由液面,产生紊流,缩孔、缩松缺陷增多,铸件性能下降。

By use of self-designed and installed centrifugal counter-gravity casting （C3） machine, and design of investment mold, the effects of speed of rotation on mechanical properties of ZL114A aluminium alloy castings by C3 process were studied. The results show that the centrifugal force could enhance the solidification feeding capacity, because of the convection of liquid metal blocked the dendrite growth during the centrifugal process, the microstructures of C3 castings became more homogeneous and the grains refined; compared with the vacuum suction casting, C3 could significantly improve the tensile strength and elongation. At 100 r/min, the highest tensile strength was 373.37 MPa, the elongation was 9.99%, higher than that of the vacuum suction castings by 7% and 44%, respectively; at 200 r/min, excessive centrifugal speed destroyed the flee surface of liquid metal, produced the turbulence, increased shrinkage and dispersed shrinkage, and the mechanical properties of castings declined.