Non-heat-treated high-toughness die-casting aluminum-silicon alloy and preparation method therefor

Abstract

This invention discloses a non-heat treatable die-cast aluminum-silicon (Al—Si) alloy with high toughness and its preparation method. By controlling the Mn/Fe ratio to a specific value, the adverse effects of Fe in the alloy can be effectively suppressed. In addition, a certain proportion of rare earth elements are introduced into the alloy to effectively refine the Si and form high-temperature phases with elements such as Al and Cu, therefore improving the deformation resistance of the alloy when applied to one-piece die-cast large-scale structural parts. When taking specimens from the casting after die casting for testing, the specimens have the following properties: tensile strength 290 Mpa, yield strength 140 Mpa, and elongation 13%. The alloy also has excellent die-cast molding performance, and the energy used is clean, which meets low-carbon emission standards.

1 . A non-heat treated die-cast Al—Si alloy consisting of the following components, in percent by weight:
 Si: 6.3-8.3%; 
 Fe: 0.07-0.45%; 
 Cu: 0.05-0.5%; 
 Mn: 0.5-0.8%; 
 Mg: 0.15-0.35%; 
 Ti: 0.01-0.2%; 
 Sr 0.015-0.035%; 
 rare earth elements: 0.04%-0.2%; 
 Ni: 0.001-0.1%; 
 Zn: 0.005-0.1%; 
 Ga: 0.01-0.03%; 
 the total amount of other impurities is less than or equal to 0.2%, and the balance is Al; and 
 wherein the rare earth elements include at least one of La, Ce, and Sc. 
 
     
     
         2 . The non-heat treated die-cast Al—Si alloy according to  claim 1 , consisting of the following components (in percent by weight):
 Si: 6.3-7.0%; 
 Fe: 0.2-0.4%; 
 Cu: 0.35-0.45%; 
 Mn: 0.5-0.8%; 
 Mg: 0.25-0.35%; 
 Ti: 0.1-0.2%; 
 Sr 0.015-0.035%; 
 rare earth elements: 0.04%-0.2%; 
 Ni: 0.001-0.1%; 
 Zn: 0.005-0.1%; 
 Ga: 0.01-0.03%; 
 the total amount of other impurities is less than or equal to 0.2%, and the balance is Al; and 
 wherein the rare earth elements include at least one of La, Ce, and Sc. 
 
     
     
         3 . The non-heat treated die-cast Al—Si alloy according to  claim 1 , consisting of the following components (in percent by weight):
 Si: 6.4-7.1%; 
 Fe: 0.10-0.25%; 
 Cu: 0.05-0.28%; 
 Mn: 0.5-0.8%; 
 Mg: 0.25-0.35%; 
 Ti: 0.03-0.16%; 
 Sr 0.025-0.035%; 
 rare earth elements: 0.04%-0.15%; 
 Ni: 0.001-0.1%; 
 Zn: 0.005-0.1%; 
 Ga: 0.01-0.03%; 
 the total amount of other impurities is less than or equal to 0.2%, and the balance is Al; and 
 wherein the rare earth elements include at least one of La, Ce, and Sc. 
 
     
     
         4 . The non-heat treated die-cast Al—Si alloy according to  claim 1 , consisting of the following components (in percent by weight):
 Si: 7.0-7.7%; 
 Fe: 0.15-0.3%; 
 Cu: 0.2-0.35%; 
 Mn: 0.6-0.8%; 
 Mg: 0.2-0.3%; 
 Ti: 0.05-0.2%; 
 Sr 0.015-0.035%; 
 rare earth elements: 0.04%-0.2%; 
 Ni: 0.001-0.1%; 
 Zn: 0.005-0.1%; 
 Ga: 0.01-0.03%; 
 the total amount of other impurities is less than or equal to 0.2%, and the balance is Al; and 
 wherein the rare earth elements include at least one of La, Ce, and Sc. 
 
     
     
         5 . The non-heat treated die-cast Al—Si alloy with high toughness according to  claim 1 , is characterized in that the die-cast Al—Si alloy consists of the following components (in percent by weight):
 Si: 7.7-8.3%; Fe: 0.07-0.2%; Cu: 0.05-0.2%; Mn: 0.6-0.8%; Mg: 0.15-0.3%; Ti: 0.01-0.15%; Sr: 0.015-0.035%; rare earth elements: 0.04%-0.2% (the rare earth elements include at least one of La/Ce/Sc); Ni: 0.001-0.1%; Zn: 0.005-0.1%; Ga: 0.01-0.03%; the total amount of other impurities shall be less than or equal to 0.2%, and the balance is Al. 
 
     
     
         6 . The non-heat treated die-cast Al—Si alloy according to  claim 1 , wherein the die-cast Al—Si alloy has a tensile strength greater than or equal to 270 Mpa, a yield strength greater than or equal to 130 Mpa, and an elongation greater than or equal to 11%. 
     
     
         7 . A method for preparing the non-heat treatable treated die-cast Al—Si alloy with high toughness according to  claim 1 , comprising the following ordered steps:
 heating and melting the components not easy to cause burning loss to obtain a molten aluminum alloy; 
 de-slagging and refining the molten aluminum alloy before adding the components that are easy to cause burning loss; 
 after the composition reaches the specified value, pouring the molten alloy into molds to obtain the die-cast Al—Si alloy. 
 
     
     
         8 . The method according to  claim 7 , wherein the molten alloy is die-cast at a die-casting temperature is of 680-720° C., a die-casting speed of 2.5-5 m/s, and a holding time is of 2-10 s. 
     
     
         9 . The method according to  claim 7 , further comprising the following steps: after all of the components are completely melted, the molten aluminum alloy is stirred well, left to stand and then sampled and analyzed, and then adjusting the weight percentage of the components to the required composition range. 
     
     
         10 . The method according to  claim 7 , further comprising using a refining agent that does not contain Na ions. 
     
     
         11 . The non-heat treatable die-cast Al—Si alloy according to  claim 2 , wherein the die-cast Al—Si alloy has a tensile strength greater than or equal to 270 Mpa, a yield strength greater than or equal to 130 Mpa, and an elongation greater than or equal to 11%. 
     
     
         12 . The non-heat treatable die-cast Al—Si alloy according to  claim 3 , wherein the die-cast Al—Si alloy has a tensile strength greater than or equal to 270 Mpa, a yield strength greater than or equal to 130 Mpa, and an elongation greater than or equal to 11%. 
     
     
         13 . The non-heat treatable die-cast Al—Si alloy according to  claim 4 , wherein the die-cast Al—Si alloy has a tensile strength greater than or equal to 270 Mpa, a yield strength greater than or equal to 130 Mpa, and an elongation greater than or equal to 11%. 
     
     
         14 . The non-heat treatable die-cast Al—Si alloy according to  claim 5 , wherein the die-cast Al—Si alloy has a tensile strength greater than or equal to 270 Mpa, a yield strength greater than or equal to 130 Mpa, and an elongation greater than or equal to 11%.