以ZL104铝合金为研究对象，采用金属型低压铸造和砂型铸造工艺，对比研究了超长激光切割机铝合金箱梁组织和力学性能。结果表明，金属型低压铸造的铝合金箱梁的横梁和底座的屈服强度和抗拉强度均高于砂型铸造的，相同铸造工艺条件下，底座性能均优于横梁的；金属型低压铸造的箱梁试样晶粒均比砂型铸造的细小，组织更加均匀；砂型铸造试样组织中Si的分布不均匀，存在大量偏析，而金属型低压铸件Si元素分布相对均匀；金属型低压铸造箱梁组织中二次枝晶间距比砂型铸造的降低60%左右，力学性能提高20%以上。

Taking ZL104 aluminum alloy as the research object, the microstructure and mechanical properties of aluminum box girder with ultra-long laser cutting machine were studied by using metal mould low-pressure casting and sand casting. The results show that the yield strength and tensile strength of the beam and the base of the aluminum box girder cast by metal mold low-pressure casting are higher than those cast by sand mold, and the properties of the base are better than those of the beam under the same casting process. The grain size of the box girder samples cast by metal mold low-pressure casting is smaller than that cast by sand mold, and the microstructure is more uniform. The distribution of Si in sand casting sample is not uniform and there is a lot of segregation, while the distribution of Si in metal mold low-pressure casting is relatively uniform. Compared with sand casting, the secondary dendrite spacing in metal low-pressure casting box girder is about 60% lower and the mechanical properties are more than 20% higher.