High-strength and high-toughness non-heat-treatable die-casting aluminum-silicon alloy and preparation method therefor

Abstract

A high-strength and high-toughness non-heat-treatable die-casting aluminum-silicon alloy and a preparation method therefor are provided. The alloy includes the following components in percentage by weight: 8.0-10.0% of Si, 0.1-0.5% of Mg, 0.5-0.8% of Mn, 0.05-0.5% of Cu, 0.05-0.2% of Ti, 0.01-0.05% of Sr, 0.01-0.1% of V, 0.01-0.15% of RE, less than 0.2% of Fe, less than or equal to 0.4% of other impurities and the balance of Al. Based on modification refinement of eutectic Si by Sr, during preparation, the elements V and RE are imported to further significantly refine eutectic Si structures, so that the alloy obtains features of high strength and high toughness with a high Si content. Under a die-casting condition, the yield strength of the alloy can be 120-160 Mpa, the tensile strength thereof can be 260-320 Mpa and the ductility thereof can be 10-15%.

1 . A high-strength and high-toughness non-heat-treatable die-casting aluminum-silicon alloy, comprising the following components in percentage by weight: 8.0-10.0% of Si, 0.1-0.5% of Mg, 0.5-0.8% of Mn, 0.05-0.5% of Cu, 0.05-0.2% of Ti, 0.01-0.05% of Sr, 0.01-0.1% of V, 0.01-0.15% of RE, less than 0.2% of Fe, less than or equal to 0.4% of other impurities, and a balance of Al. 
     
     
         2 . The high-strength and high-toughness non-heat-treatable die-casting aluminum-silicon alloy according to  claim 1 , wherein the RE comprises one or more of elements La, Ce, and Er. 
     
     
         3 . A method for preparing the high-strength and high-toughness non-heat-treatable die-casting aluminum-silicon alloy according to  claim 1 , comprising the following steps:
 S1: drying: pre-heating prepared raw materials of pure Al, pure Si, pure Mg, an Al—Mn intermediate alloy, an Al—Ti intermediate alloy, an Al—Cu intermediate alloy, an Al-RE intermediate alloy, and an Al—V intermediate alloy for a drying treatment; and   S2: smelting: adding the Al—Ti intermediate alloy, the Al—Cu intermediate alloy, the Al—Mn intermediate alloy, the Al—V intermediate alloy, and the pure Si after melting the pure Al by a preliminary heating to obtain a first resulting alloy melt, and performing a cooling on the first resulting alloy melt after melting the pure Si, the Al—Ti intermediate alloy, the Al—Cu intermediate alloy, the Al—Mn intermediate alloy, the Al—V intermediate alloy to obtain a second resulting alloy melt; pressing the pure Mg into a bottom of the second resulting alloy melt for melting to obtain a third resulting alloy melt, and performing a secondary heating on the third resulting alloy melt for a refinement of the third resulting alloy melt after completely melting the pure Mg to obtain a fourth resulting alloy melt; and then pressing the Al-RE intermediate alloy into a bottom of the fourth resulting alloy melt for melting to obtain a fifth resulting alloy melt, and leaving the fifth resulting alloy melt still after completely melting the fifth resulting alloy melt to obtain the high-strength and high-toughness non-heat-treatable die-casting aluminum-silicon alloy.   
     
     
         4 . The method according to  claim 3 , wherein a pre-heating temperature in S1 is 190-210° C. 
     
     
         5 . The method according to  claim 3 , wherein a preliminary heating temperature in S2 is 750-760° C. 
     
     
         6 . The method according to  claim 3 , wherein a cooling temperature in S2 is 680-700° C. 
     
     
         7 . The method according to  claim 3 , wherein a secondary heating temperature in S2 is 720-730° C. 
     
     
         8 . The method according to  claim 3 , wherein the refinement in S2 specifically comprises: introducing a nitrogen with a refining agent powder into the third resulting alloy melt by using a rotary blowing device for an injection refining to obtain a first refined melt, performing a deslagging treatment and a degassing treatment on the first refined melt to obtain a second refined melt, then leaving the second refined melt still for 10-15 min, and completing a slagging-off treatment on the second refined melt to obtain the fourth resulting alloy melt. 
     
     
         9 . The method according to  claim 8 , wherein process parameters for the rotary blowing device are as follows: a degassing revolution is 300-350 r/min; a degassing time is 5-10 min, a pressure of a gas source during the degassing treatment is 0.35±0.05 MPa, and a gas flow is 0.2-0.8 sccm. 
     
     
         10 . The method according to  claim 8 , wherein the refining agent powder comprises one of magnesium chloride and calcium chloride.