Study On High-strength And Toughness Aluminum Alloys Formed By Indirect Squeeze Casting

With the development of modern industry, the need of structures existed stengthen and toughening and light-weight together is urgent. So the high strength and toughness aluminum alloys has its development chance. In the experiment, via the indirect squeeze casting to form Al-Cu alloy mainshaft retainer of high speed machine tool, and Al-Cu alloy is as research target, the effects on the casts mechanical properties and microstructure of squeeze casting process parameter, the content of elements and heat treatment are investigated. And the influence factors of hot-cracking of Al-Cu alloy is researched preliminary.The results of experiments show that the best indirect squeeze casting process parameter is the intensity of pressure is 80MPa, the mould temperature is 200℃, the pouring temperature is 750℃, and the time of pressure holding is 24s. under the parameter, the mechanics performance of casting on cast is σ_b =240²60MPa, δ₅ =9¹1.5%. At the same time, the effect ofpouring temperature and mould temperature on hot-cracking tendency is biggest, the second effect factor is hold-pressure time, and the influence of intensity of pressure on hot-cracking tendency is smallest. In the experiment, the content of three alloy elements included V, Zr, Mn is changed. The result find that V decrease the hot-cracking tendency, Zr increase it and the tendency of hot-cracking is smallest while Mn is 0.7%. And the result shows that the mechanics performance of alloy is highest when the content of element is 0.15% V, 0.12% Zr, 0.5%Mn. Heat treatment is mainly strengthen and toughening way of Al-Cu alloy. Through the solution of 525℃ ×9h, the mechanics performance of Al-Cu alloy has large-range increasing, the value is σ_b=360.9MPa, δ₅=18.4%. When the treatment of aging 175℃×15h followed by 525℃×9h, the strength of alloy is biggest, the value is σ_b=465MPa;the hardness of alloy is increasing with the prolong of aging time, the biggest one is HB 126;but the elongation is decreasing with the prolong of hold-time during aging treatment. From the last result, the strength and toughness of alloy achieved in the experiment is both higher. The result shows that high strength and toughness aluminum alloy can be achieved through changing the content ofalloy elements and the way of heat treatment under the certain indirect squeeze casting process parameters. And the effect of heat treatment is most obvious.Last, the satisfactory retainer cages of high speed machine tool was obtained using the better alloy elements and under the best indirect squeeze casting process parameters.