[TheForge] Metalurgy news Super Bainite armor

[Rob Fertner]

A Whole New Type Of Protective Armour

by Staff Writers
Porton Down, UK (SPX) Jan 21, 2009

Developing protective vehicle armour with holes in it may not seem the most
obvious way to increase protection for British troops on operations but
that's just what MOD scientists are doing.
Since 2000, the Defence Science and Technology Laboratory (DSTL) at Porton
Down in Wiltshire has worked in collaboration with Cambridge University and
QinetiQ to develop Super Bainite, a unique ultra-hard armour material.

It may seem like a strange solution but introducing holes to vehicle armour
can actually provide a protective advantage. DSTL scientist Professor Peter
Brown explained:

"You shouldn't think of them as holes, you should think of them as edges.
When a bullet hits an edge, it gets deflected, and turns from a sharp
projectile into a blunt fragment - which is much easier to stop."

The introduction of holes also reduces weight he adds and doubles the
ballistic performance, making perforated Super Bainite steel armour
ballistically very efficient.

Invented, designed and manufactured in the UK, Super Bainite is an
experimental high performance armour steel developed to save the lives of UK
Armed Forces and the armour has performed well in ballistic testing at the
Ministry of Defence's firing ranges.


Unlike conventional steels, the composition of Super Bainite was derived
from first principles using thermodynamic modelling techniques. This allowed
its processing, properties and cost to be optimised in months rather than
years.

It has been know since the 1930s that certain heat treatments alter the
fine-scale structure of steel creating a 'phase' called bainite, but in
collaboration with steelmaker Corus, DSTL scientists have developed a new
manufacturing process, which allows the alloy to be produced quickly and
cost effectively.

Whilst other armour steels need to be quenched and tempered, Super Bainite
develops its properties by a low temperature mechanism called isothermal
hardening. This enables ultra-high levels of hardness to be achieved without
having to use expensive alloying additions.

Isothermal hardening involves the steel being heated to 1,000C, cooled to
about 200C, and then held at this temperature for a period of time before
cooling to room temperature. This is how the Super Bainite develops its
exceptional strength.

Traditionally the MOD has utilised offshore suppliers to fulfil its
specialist armour requirements. However, following the successful industrial
production trials, directed by DSTL in partnership with Corus and Bodycote,
the UK is now well placed to develop a secure onshore supply of specialist,
high hardness steel armour.

Professor Peter Brown added:

"Due to the unique process by which we have developed this new armour, Super
Bainite is able to match the ballistic performance of the best off-shore
armour steels at reduced cost."