镁合金真空低压消失模铸造的技术特征与实践

介绍了镁合金在真空低压消失模铸造下的技术特征。研究表明：真空低压消失模铸造的流动性受充型气体的流量与压力、浇注温度、涂层厚度、泡沫密度、真空度等多方面的因素影响；在低充型速度和低真空度的条件下，液态镁合金在真空低压消失模铸造过程中的充型形貌均呈现以内浇道为中心的拱形层状推进流动，如充型速度加快金属液流动前沿拱形形貌更加突出。而真空度增加会出现明显的“附壁效应”；与重力消失模铸造比较，真空低压消失模铸造镁合金铸件凝固更呈现“同时凝固”特征；由于快速充型、压力下凝固，镁合金真空低压消失模铸造零件的铸态抗拉强度（σh=180．8MPa）、屈服强度（σ0.2=113．2MPa）、伸长率（δ=4．4％），高于重力消失模铸造、树脂砂空型铸造的铸态性能，达到了金属型铸造的铸态性能，经热处理达到了压铸镁合金的性能范围。浇注实践表明，真空低压消失模铸造对液态镁合金，具有良好的抗氧化保护能力、优良的浇注充型性能和力学性能，可铸造出高精度的、薄壁复杂的镁合金消失模铸件，是一种极有潜力和优势的镁（铝）合金精密铸造技术。

Technological Characteristics and Practice of the Low Pressure-expendable Pattern Casting Process for Magnesium Alloy

The technological characteristics of Mg alloy in low pressure-expendable pattern casting were described. Following facts are shown: ( 1) the fluidity of molten metal in LP-EPC is affected by the flux and pressure of filling gas, casting temperature, coating thickness, foam density and vacuum level; (2) filling shape of molten metal in LP-EPC is presented in arch and layer forming from the in-gate on the condition of low filling velocity and low vacuum level, and filling shape would be more protuberant with high filling velocity, and attached wall effects are shown with high vacuum level. ; (3) the solidification of Mg alloy in LP-EPC advents the simultaneous solidification earlier compared with EPC; (4 ) mechanical properties of the Mg alloy in LP-EPC, such as tensile strength 180.8 MPa, yield strength 113.2 MPa, elongation 4.4%, are superior to those in EPC and in resin sand casting, and equivalent to that in metal mold casting, which can meet the performance requirements of die casting Mg alloy after heat treatment. Production verifies that Mg alloy in LP-EPC has the advantages of good anti-oxidation ability, excellent fillingperformance and mechanical properties, and can produce high precision and thin-walled complex components.