Corus develops new low cost armour steel
03 Oct 2008
Corus has been working with the UK Ministry of Defence to develop a new high-strength armour plate steel at a lower cost. The new Super Bainite steel was originally developed by Cambridge University, QinetiQ and the UK’s MOD Defence Science and Technology Laboratory (Dstl). Corus took the project from academic research to final product using its experimental, pilot and full-scale production facilities.
The new steel has been produced with a 5-tonne cast at the Corus Teesside Technology Centre’s pilot plant steel making facilities. Subsequent rolling operations at Corus Engineering Steels Stocksbridge and CES Narrow Strip produced 6mm and 8.5mm strip. This was then heat treated at Bodycote to impart the final required properties. Corus’ Swinden Technology Centre determined the cooling rate window, slow enough to avoid cracking but sufficiently fast to avoid carbide.
Unlike conventional armour steels, which use a quench and temper process and additions of chromium and nickel, the new steel develops an ultrafine bainitic microstructure by low temperature isothermal transformation. This technique offers significant cost savings, compared to conventional armour steels, due to the lower alloy content and the removal of the need for tempering during final heat treatment.
The steel's high carbon content and the ability to develop an ultra high strength microstructure mean careful control is required during hot rolling and cooling to avoid cracking.
The result is a new type of armour described by Peter Brown from Dstl as “able to match the ballistic performance of the best off-shore armours at reduced cost.”
The next stage, full-scale production, is currently being evaluated.
