Method for manufacturing of vehicle armor components requiring severe forming with very high bend angles with very thick gauge product of high strength heat treatable aluminum alloys

Abstract

It has been commonly believed that very thick gauge high strength aluminum alloy product such as AA2139 plate cannot be formed to the required sharp angles to form the highly protective underbody armor for the MRAP vehicles. The present process and method of manufacture provides a means for strategically combining the metallurgical process of manufacturing high strength aluminum alloys and the forming process of V shaped hull to improve the formability of the very thick gauge high strength alloy product so much that even the very thick gauge (thicker than 1 inch) plate can be formed to severe forming angles. This combined process allowed successful manufacturing of high performance V shaped hulls for the Mine Resistant Ambush Protected (MRAP) vehicles.

1 . A method of manufacturing highly effective vehicle armor with very thick gauge high strength heat treatable aluminum alloys by strategically combining forming process and the metallurgical process of the alloy
 a) Thick gauge aluminum alloy products comprised of the thickness range of from 1 inch to 6 inch thick product   b) High strength heat treatable aluminum alloys comprised of;
 i) high strength 2000 series aluminum alloys such as, but not limited to, AA2139, AA2027, and AA 2519 
 ii) high strength 7000 series aluminum alloys such as, but not limited to, AA7085 and AA7081 
   c) forming process requires solution heat treatment of the work piece at the solutionization temperature and quench the work piece to room temperature to condition the work piece to be capable of receiving severe forming process by bending or bending and stretching at various bending angles more severe than 160 degrees of bending angle to meet the geometry requirement of the vehicle armor component   d) If desired, a forming process can add a cold stretch by a small amount after quench the work piece to further improve the material properties prior to forming the work piece.   e) The formed armor components can be aged to increase the strength of the material to take advantage of age hardening characteristics of heat treatable aluminum alloys.   
     
     
         2 . Forming process according to the  claim 1 , wherein forming the work piece immediately after solution heat treatment and quench step to maximize the formability during bend forming or stretch and bend forming procedure. The solution heat treatment for high strength 2000 series alloys can be conducted at the temperature range of 960° F. and 980° F. for the durations to be adjusted to the thickness of the work piece. The solution heat treatment for high strength 7000 series alloys can be conducted at the temperature range of 860° F. and 880° F. for the durations to be adjusted to the thickness of the work piece. 
     
     
         3 . Forming process according to the  claim 1 , wherein forming the work piece after solution heat treatment and quench step to maximize the formability during bend forming or stretch and bend forming procedure. For very thick plate of 2000 series aluminum alloys such as 1 inch to 6 inch thick gauge 2139 alloy plate and 2519 alloy plate can be solution heat treated at 960° F.-980° F. for the duration of 30 minutes to 6 hours depending on the thickness of the work piece and cold water quench for conditioning the work piece to be ready for forming operation. For 2.5 inch thick work piece, 2-4 hours of heat treatment at the temperature arrange of 960° F.-980° F. would be most preferred After forming the work piece to the final shape, the work piece can be age hardened to meet high ballistic and blast resistance for the armored vehicles. Age hardening can be conducted at the temperature range of 250-380° F. for the duration of 6 hours to 72 hours depending on the actual age temperatures selected. This age process can be further modified if required such as need to compensate the limitation of equipment limitations to achieve the final age processing effect. A cold stretch of the work piece by a small amount right after the solution heat treatment can be a part of the conditioning the work piece for forming operation. This would further improve the final mechanical properties and minimize the residual stress of the formed and age hardened work piece in the final temper condition. 
     
     
         4 . Forming process according to the  claim 1 , wherein forming the work piece after solution heat treatment and quench step to maximize the formability during bend forming or stretch and bend forming procedure. For very thick plate of 7000 series aluminum alloys such as 1 inch to 6 inch thick gauge 7085 alloy plate and 7081 alloy alloy plate can be solution heat treated at 860° F.-880° F. and cold water quenched to condition the work piece to be ready for forming operation. After forming the work piece to the final shape, the work piece can be age hardened to meet high ballistic and blast resistance for the armored vehicles. A cold stretch of the work piece by a small amount right after the solution heat treatment can be a part of the conditioning the work piece for forming operation. This would further improve the final mechanical properties and minimize the residual stress of the formed and age hardened work piece in the final temper condition.