Armour

Abstract

A steel armour comprising between 90% and 50% bainite, the rest being austenite, in which excess carbon remains within the bainitic ferrite at a concentration beyond that consistent with equilibrium; there is also partial partitioning of carbon into the residual austenite. In one embodiment of the invention the bainite comprises in weight percent: carbon 0.6 to 1.1%, silicon 1.5 to 2.0%, manganese 0.5 to 1.8%, nickel up to 3%, chromium 1.0 to 1.5%, molybdenum 0.2 to 0.5%, vanadium 0.1 to 0.2%, balance iron save for incidental impurities. In particular it was noted that excellent properties were obtained if the manganese content is about 1% by weight. By forming the steel as a pearlite sheet the elements ( 310,410 ) of the panel can be formed easily by cutting or stamping before final transformation to bainite. Cutting may also occur after final transformation using water- jet or laser cutting. Alternatively hot forging elements is described. The invention notes that such armours may have holes or slots to fragment incoming projectiles.

1 . Armour comprising a plurality of elements of a carbide free bainite steel which comprises between 90% and 50% bainite, the rest being austenite, in which excess carbon remains within the bainitic ferrite at a concentration beyond that consistent with equilibrium. 
     
     
         2 . Armour according to  claim 1  wherein the bainite steel comprises by weight percent: carbon 0.6% to 1.1%; manganese 0.3% to 4%; nickel up to 3%; chromium 0.5% to 1.5%; molybdenum up to 0.5%; vanadium up to 0.2%, silicon in the range about 0.5% by weight to about 2% by weight and the balance iron save for incidental impurities. 
     
     
         3 .- 9 . (canceled) 
     
     
         10 . Armour according  claim 1  wherein one or more elements has one or more holes therethrough. 
     
     
         11 . Armour according to  claim 10  wherein the holes comprise slots. 
     
     
         12 . Armour according to  claim 1  additionally comprising one or more bridges between adjacent elements. 
     
     
         13 . Armour according to  claim 12  wherein the sides of elements are uniformly spaced apart and a bond line is formed between the sides of the adjacent armour elements. 
     
     
         14 . Armour according to  claim 12  wherein the bridges are at corners formed between adjacent sides of elements. 
     
     
         15 . Armour according to  claim 12  wherein the elements comprise a fret like structure. 
     
     
         16 . Armour according to  claim 12  wherein the elements are hexagonal. 
     
     
         17 . Armour according to  claim 1  wherein an element has a lug on a side said lug separating said side from the side of an adjacent element. 
     
     
         18 . Armour as claimed in  claim 1  wherein the elements have a lug on each of their sides. 
     
     
         19 . Armour as claimed in  claim 18  wherein the lugs on each side of a first element are entirely on one hand (left or right) of the sides of the first element, the lugs on adjacent sides of a second element are entirely on the opposing hand of the sides of said second element when compared to the first element. 
     
     
         20 . Armour as claimed in  claim 19  wherein the lugs on each side of a first element are entirely on one hand of the sides of the said first element, the lugs on the sides of an adjacent second element are entirely on the opposing hand of the sides of said second element when compared to the first element and when the first element is rotated 60° about an axis of symmetry the position of the lugs on said first element in relation to the second element is substantially the same. 
     
     
         21 . Armour according to  claim 1  wherein an elastomeric material encapsulates the elements. 
     
     
         22 . Armour according to  claim 21  wherein a bond line between adjacent elements is filled, at least in part, with recycled material from vehicle tyres. 
     
     
         23 . Armour according to  claim 1  wherein individual elements are disposed between two layers. 
     
     
         24 . (canceled) 
     
     
         25 . A method of manufacture of armour including the steps of forming austenite steel comprising carbon 0.6% to 1.1%; manganese 0.3% to 4%; nickel up to 3%; chromium 0.5% to 1.5%; molybdenum up to 0.5%; vanadium up to 0.2%; sufficient silicon and or aluminium to render the bainite substantially carbide free; and the balance iron save for incidental impurities, cooling the steel sufficiently quickly to avoid the formation of pearlite to a temperature above its martensite start temperature but below the bainite start temperature and holding the steel with that temperature range for up to a week and a transforming step wherein the steel is transformed to a carbide free bainite steel which comprises between 90% and 50% bainite, the rest being austenite, in which excess carbon remains within the bainitic ferrite at a concentration beyond that consistent with equilibrium. 
     
     
         26 . (canceled) 
     
     
         27 . A method of manufacture of armour according to  claim 25  wherein it additionally includes the step of forming a sheet of pearlite steel prior to the transforming step and cutting said pearlite sheet to form armour elements. 
     
     
         28 . A method of manufacture of armour according to  claim 27  wherein it includes the step of forming bridges between the elements. 
     
     
         29 . A method of manufacture of armour according to  claim 28  wherein it additionally includes the step of rendering said bridges more ductile than the elements. 
     
     
         30 . (canceled) 
     
     
         31 . A method of manufacture of an armour according to  claim 27  wherein it additionally includes the step of the formation of one or more holes or slots in one or a plurality of elements. 
     
     
         32 . A method of manufacture of an armour according to  claim 25  wherein armour elements are hot forged when the steel is austenitic.