Aluminum alloy that is not sensitive to quenching, as well as method for the production of a semi-finished product therefrom

Abstract

An aluminum alloy that is not sensitive to quenching, for the production of high-strength forged pieces that are low in inherent tension, and high-strength extruded and rolled products, consisting of: 7.0-10.5 wt. % zinc, 1.0-2.5 wt. % magnesium, 0.1-1.15 wt. % copper, 0.06-0.25 wt. % zirconium, 0.02-0.15 wt. % titanium, at most 0.5 wt. % manganese, at most 0.6 wt. % silver, at most 0.10 wt. % silicon, at most 0.10 wt. % iron, at most 0.04 wt. % chrome, and at least one element selected from the group consisting of: hafnium, scandium, strontium and/or vanadium with a summary content of at most 1.0 wt. %. The alloy can also contain contaminants at proportions of at most 0.05 wt. % per element and a total proportion of at most 0.15 wt. %, wherein the remaining component includes aluminum. The sum of the alloy elements zinc and magnesium and copper is at least 9 wt. %. Furthermore, there can also be a method for the production of a high-strength semi-finished product low in inherent tension from this alloy.

1 . An aluminum alloy that is not sensitive to quenching, for the production of high-strength forged pieces that are low in inherent tension, and high-strength extruded and rolled products, consisting of: 
 7.0-10.5 wt. % zinc;    1.0-2.5 wt. % magnesium;    0.1-1.15 wt. % copper;    0.06-0.25 wt. % zirconium;    0.02-0.15 wt. % titanium;    at most 0.5 wt. % manganese;    at most 0.6 wt. % silver;    at most 0.10 wt. % silicon;    at most 0.10 wt. % iron;    at most 0.04 wt. % chrome;    at least one element selected from the group consisting of:    hafnium, scandium, strontium and vanadium with a summary content of at most 1.0 wt. %; and    a plurality of contaminants at proportions of at most 0.05 wt. % per element with a total contaminant proportion of at most 0.15 wt. %;    wherein a remaining amount by wt % is aluminum; and    wherein a sum of the alloy elements zinc and magnesium and copper is at least 9 wt. %.    
   
   
       2 . The aluminum alloy according to  claim 1 , wherein an amount of zinc and magnesium is in the form of a zinc:magnesium ratio that is between 4.4 and 5.3.  
   
   
       3 . The aluminum alloy according to  claim 2 , wherein the alloy contains 1.6-1.8 wt. % magnesium and 0.8-1.1 wt. % copper.  
   
   
       4 . The aluminum alloy according to  claim 1 , wherein the aluminum alloy contains 0.8-1.1 wt. % copper and 0.3-0.5 wt. % manganese.  
   
   
       5 . The aluminum alloy according to  claim 1 , wherein said aluminum alloy contains 0.8-1.1 wt. % copper and at most 0.03 wt. % manganese.  
   
   
       6 . The aluminum alloy according to  claim 1 , wherein the aluminum alloy contains 0.2-0.3 wt. % copper and 0.25-0.40 wt. % silver.  
   
   
       7 . The aluminum alloy according to  claim 1 , wherein the aluminum alloy contains 0.10-0.15 wt. % titanium.  
   
   
       8 . The aluminum alloy according to  claim 1 , wherein the aluminum alloy contains 0.001-0.03 wt. % boron.  
   
   
       9 . The aluminum alloy according to  claim 1 , wherein the aluminum alloy contains at most 0.30 wt. % scandium and at most 0.2 wt. % vanadium, hafnium or cerium.  
   
   
       10 . The aluminum alloy as in  claim 1 , wherein the iron and silicon content is at most 0.08 wt. %, in each instance.  
   
   
       11 . A method for the production of a high-strength semi-finished product low in inherent tension, up to greater thickness values, comprising the following steps: 
 providing an aluminum alloy consisting of: 7.0-10.5 wt. % zinc, 1.0-2.5 wt. % magnesium, 0.1-1.15 wt. % copper, 0.06-0.25 wt. % zirconium, 0.02-0.15 wt. % titanium, at most 0.5 wt. % manganese, at most 0.6 wt. % silver, at most 0.10 wt. % silicon, at most 0.10 wt. % iron, at most 0.04 wt. % chrome, at least one element selected from the group consisting of: hafnium, scandium, strontium and vanadium with a summary content of at most 1.0 wt. %, a plurality of other contaminants at proportions of at most 0.05 wt. % per element with a total contaminant proportion of at most 0.15 wt. %, wherein the remaining amount is aluminum, whereby the sum of the alloy elements zinc and magnesium and copper is at least 9 wt. %.    hot forming a plurality of homogenized bars via forging, extrusion and/or rolling, in a temperature range of 350-440° C.;    solution heat treating said hot-formed semi-finished product at a temperature sufficiently high to bring the alloy elements necessary for hardening into solution uniformly distributed in the structure;    quenching of the solution heat treated semi-finished products in a quenching medium comprising water, in a water/glycol mixture, or in a salt mixture at a temperature between 100° C. and 170° C.;    cold forming the quenched semi-finished product to reduce a set of inherent tensions that occurred during quenching in the quenching medium; and    artificial aging the quenched semi-finished product, in at least one stage, wherein a heating rate, holding time, and temperature is adjusted for optimization of the properties.    
   
   
       12 . The method according to  claim 11 , wherein the step of cold forming occurs by means of upsetting or stretching the semi-finished product.  
   
   
       13 . The method according to  claim 11 , wherein the cold forming rate is 1-5%.  
   
   
       14 . A method for the production of a high-strength semi-finished product low in inherent tension, of medium thickness, from an aluminum alloy, comprising the following steps: 
 providing an aluminum alloy consisting of: 7.0-10.5 wt. % zinc, 1.0-2.5 wt. % magnesium, 0.1-1.15 wt. % copper, 0.06-0.25 wt. % zirconium, 0.02-0.15 wt. % titanium, at most 0.5 wt. % manganese, at most 0.6 wt. % silver, at most 0.10 wt. % silicon, at most 0.10 wt. % iron, at most 0.04 wt. % chrome, at least one element selected from the group consisting of: hafnium, scandium, strontium and/or vanadium with a summary content of at most 1.0 wt. %, a plurality of other contaminants at proportions of at most 0.05 wt. % per element with a total contaminant proportion of at most 0.15 wt. %, wherein the remaining amount is aluminum, whereby the sum of the alloy elements zinc and magnesium and copper is at least 9 wt. %.    hot forming of a set homogenized bars by means of forging, extrusion and/or rolling, in a temperature range of 350-440° C.;    solution heat treating the hot-formed semi-finished product at a temperature that is sufficiently high to bring the alloy elements necessary for hardening into solution uniformly distributed in the structure;    quenching of the solution heat treated semi-finished products in water, in a water/glycol mixture, or in a salt mixture at temperatures between 100° C. and 170° C.; and    artificially aging the quenched semi-finished product, in at least one stage, whereby the heating rates, holding times, and temperatures are adjusted for optimization of the properties.    
   
   
       15 . The method according to  claim 14 , wherein after the step of hot forming, there is formed a semi-finished product having a greater thickness, which is processed in cutting manner before the subsequent heat treatment, in the way of pre-cutting, to reduce the thickness of the semi-finished product by means of the cutting processing, to such an extent that this pre-processed semi-finished product has a medium thickness and the subsequent heat treatment is carried out in accordance with the requirements corresponding to semi-finished products having a medium thickness.  
   
   
       16 . The method as in  claim 11 , wherein the solution heat treatment step is between 465 and 500 degrees Celsius.  
   
   
       17 . The method as in  claim 14 , wherein the solution heat treatment step is between 465 and 500 degrees Celsius.