Dual-phase steel is a high-strength steel

Steel

Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 that has a ferrite

Ferrite (iron)

Ferrite or alpha iron is a materials science term for iron, or a solid solution with iron as the main constituent, with a body centred cubic crystal structure. It is the component which gives steel and cast iron their magnetic properties, and is the classic example of a ferromagnetic material...

 and martensitic

Martensite

Martensite, named after the German metallurgist Adolf Martens , most commonly refers to a very hard form of steel crystalline structure, but it can also refer to any crystal structure that is formed by displacive transformation. It includes a class of hard minerals occurring as lath- or...

 microstructure. DPA starts as a low or medium carbon steel and is quenched from a temperature above A₁ but below A₃ on a continuous cooling transformation

Continuous cooling transformation

A continuous cooling transformation phase diagram is often used when heat treating steel. These diagrams are used to represent which types of phase changes will occur if a material at it is cooled at different rates...

 diagram. This results in a microstructure

Microstructure

Microstructure is defined as the structure of a prepared surface or thin foil of material as revealed by a microscope above 25× magnification...

 consisting of a soft ferrite matrix containing islands of martensite as the secondary phase (martensite increases the tensile strength

Tensile strength

Ultimate tensile strength , often shortened to tensile strength or ultimate strength, is the maximum stress that a material can withstand while being stretched or pulled before necking, which is when the specimen's cross-section starts to significantly contract...

). The desire to produce high strength steels with formability

Formability

Formability is the ability of a given metal workpiece to undergo plastic deformation without being damaged. The plastic deformation capacity of metallic materials, however, is limited to a certain extent....

 greater than microalloyed steel

Microalloyed steel

Microalloyed steel is a type of alloy steel that contains small amounts of alloying elements . Standard alloying elements include: niobium, vanadium, titanium, molybdenum, zirconium, boron, and rare-earth metals...

 led the development of DPS in 1970s.

The steel melt is produced in an oxygen

Oxygen

Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 top blowing process in the converter, and undergoes an alloy treatment in the secondary metallurgy phase. The product is aluminum-killed steel, with high tensile strength achieved by the composition with manganese

Manganese

Manganese is a chemical element, designated by the symbol Mn. It has the atomic number 25. It is found as a free element in nature , and in many minerals...

, chromium

Chromium

Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...

 and silicon

Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...

.

Their advantages are as follows:

• Low yield strength
• Low yield to tensile strength ratio (yield strength / tensile strength
  Tensile strength
  Ultimate tensile strength , often shortened to tensile strength or ultimate strength, is the maximum stress that a material can withstand while being stretched or pulled before necking, which is when the specimen's cross-section starts to significantly contract...
  
  = 0.5)
• High initial strain hardening rates
• Good uniform elongation
• A high strain rate sensitivity (the faster it is crushed the more energy it absorbs)
• Good fatigue resistance

Due to these properties DPS is often used for automotive body panels, wheels, and bumpers.