"The Max Planck Institute for Iron Research and the German Steel Institute have developed a variety of steel that strengthens as it elongates. In the event of a car crash, the steel is ductile enough to absorb impact energy, but remains strong enough to protect occupants.
Called Twinning Induced Plasticity steel, the secret is that the steel passes the deformation energy down its length and to other parts, which also deform. The benefit is that with more area available to share the impact load, there is less that can reach the car's occupants. The institute mentions using the steel in bumpers and side doors, the most vulnerable areas in a crash.
Improved passenger safety is always good. Yet with more structures to inclined to deform, such a development would also seem to need new inspection techniques after a crash to make sure everything is still safe. Also, while the fracture point of the pictured steel is listed as 1,250-percent of elongation, it would need to be established how much elongation-before-fracture was still safe."