Stainless steel is the most widely known alloy steel. What distinguishes stainless steel from carbon steels is that it contains a minimum of 10% chromium. Steel is an alloy, or combination, of iron and carbon. Depending on the purpose of the material, different combinations of alloys and ratios are formulated for varying types of steel. Military aircraft use steel gears that are non-magnetic, high-quality, and corrosion-proof. Commercial steel buildings, roller skates, and tubing for boats and oil can be made using steel pipes. Characteristics such as strength, durability and temperature resistance can be crafted based on production method and materials used in an alloy. About 30 years ago it was discovered that some metals with suitably fine grain structure can be subjected to tremendous ductile (tensile) deformation without tearing.
With careful control of temperature and strain rate, SPF parts can be made in aluminum, titanium alloy and particular super plastic steels by deep drawing. The presses have to be specially made, but the forming pressures are quite modest. The finished part can have very small bend radii and suffer such large changes in shape that the metal literally flows. For example, a billet can be squeezed into a thin-walled part with integral stiffeners. SPF is often combined with diffusion bonding to produce complex components which in effect are a single piece of metal, instead of being made by joining perhaps a dozen separate parts.