High elongation rate and high-strength alloy aluminium end cap for multiple unit and casting method thereof

[0016] The present invention will be further described below in conjunction with embodiments.

[0017] A casting method of non-transmission end cover and middle end cover.

[0018] These two parts are installed on the traction motor of my country's newly developed EMU with a speed of 300 kilometers per hour. The weight of the parts is 21 kg and 18 kg respectively. The outline dimensions are 570×540×160mm and 550×540×200mm, and the main wall thickness is 18mm. The working condition is: the working temperature is below 150, it needs to bear a certain dynamic load, and it needs to have the ability to resist roadside flying rocks.

[0019] Raw material ratio: (calculated based on 100 kg material)

[0020] Aluminum copper master alloy (50% Cu): 0.55±0.05 kg

[0021] Magnesium ingot (above Mg-2): 5±0.05 kg

[0022] Aluminum ingot (99.85% Al): 88 kg

[0023] Aluminum titanium master alloy (4% Ti): 1.5 kg

[0024] Covering agent: MgCl2, KCl each 3 kg

[0025] Melting process:

[0026] Use a special crucible to smelt on an oil furnace. The crucible should be treated with slag removal before use. At the beginning of smelting, first add 5 to 6% of the charge weight in the red hot crucible at 500-600°C with a covering flux (after melting, a 5-10mm covering layer can be formed on the surface of the molten aluminum); after the covering agent is melted, Heat to 600~650℃, then add the preheated reheating material and pure aluminum ingot, after all melted, increase the temperature of the alloy liquid to 660~680℃. At this time, add the preheated titanium master alloy, stir carefully, and try to Do not destroy the integrity of the covering layer; if the alloy liquid is exposed to the surface, sprinkle the covering agent on the exposed area. After the master alloy is completely melted, press the preheated pure magnesium ingot at 680~720℃. In the deep part of the molten pool, stir carefully after melting; add 0.2-0.3 hexachloroethane at 690-720°C for degassing treatment; remove slag, adjust temperature, and cast molding. The pouring temperature is 700-750°C.

[0027] Casting forming method: semi-metallic low-pressure casting is adopted, the outer shape is metal, the inner cavity is made of resin sand core, and the mold is a typical upper and lower parting structure. The mold preheating temperature is 150℃~250℃, and the pouring temperature is controlled at 715℃~745℃. The filling time is 30 to 60 seconds, and the holding pressure is 0.08 MPa. The holding time is determined by the operator according to the temperature of the molten aluminum and the mold temperature. It is generally 300 to 600 seconds. After the pressure is held, the mold opening time is about 1 minute. .

[0028] Heat treatment: solid solution process: 530℃×4 hours, water quenching (water temperature 40-60℃), aging process: 200℃×4 hours, air cooling.

[0029] Mechanical properties of the casting: Take six samples from the force-bearing part of the casting body to do mechanical tests, all of which can be obtained: σb≥200(MPa), σ0.2≥100(MPa), δ5≥10%.