低压铸造凝固条件对A357合金组织及力学性能影响  

Effects of Solidification Conditions on Microstructure and Mechanical Properties of A357 Alloy by Low Pressure Casting Process

作　　者：李智伟[1] 刘新超[1] 边毅[1] 周楠 

机构地区：[1]北京航星机器制造有限公司,北京100013 [2]中船重工第十二研究所,陕西兴平713102

出　　处：《铸造》2014年第6期551-555,共5页Foundry

摘　　要：采用低压铸造的方法成形A357合金筒形铸件,研究不同凝固条件对筒形铸件组织及力学性能的影响。砂型冷却壁厚20 mm部位二次枝晶间距平均值比壁厚10 mm部位二次枝晶间距平均值大了40%以上,冷铁冷却铸件20 mm壁厚部位的二次枝晶间距比砂型凝固同壁厚铸件的二次枝晶间距小40%以上,与砂型铸造铸件壁厚10 mm部位的二次枝晶间距相当。冷铁激冷铸件的力学性能获得显著提高,相对于薄壁铸件,壁厚铸件采用冷铁对铸件的力学性能提高的幅度更大一些。凝固条件对厚壁铸件的断裂机制有一定的影响,砂型冷却20 mm壁厚铸件断裂有穿晶断裂趋势,冷铁冷却20 mm壁厚铸件断裂时有沿晶断裂趋势。By using of the low pressure casting process,A357 cylinder castings were cast and the effects of different solidification conditions on the microstructure and mechanical properties of cylinder casting were studied.When sand mold cooling wall thickness is 20 mm,the average value of secondary dendrite arm spacing is 40% more than the part where the thickness is 10 mm.At the part where the wall thickness is 20 mm cooling with chill,the secondary dendrite arm spacing is 40% less than the same thickness part cooling with sand mold.And the secondary dendrite arm spacing is the same as with that of wall thickness 10 mm cooling with sand mold.The mechanical properties of casting cooling with chill were significantly increased.Relative to the thin wall casting part,thick wall casting part cooling with chill the mechanical properties increased more dramatically.Also,the solidification conditions have impact on the fracture mechanism of thick wall casting part.For the castings of wall thickness 20 mm,the fracture type of casting with sand mold cooling has the transgranular fracture trend and the fracture type of casting with chill cooling has the intergranular fracture trend.

关 键 词：A357合金 壁厚 冷铁 力学性能 

分 类 号：TG249.2[金属学及工艺—铸造]