What is meant by dual phase steel?
Dual-phase steels (DP steels) consist of ferrite and a dispersed hard martensitic second phase in the form of islands. Usually they are low-carbon low-alloy materials with 10-40 vol. % hard martensite or martensite-austenite particles embedded in a ductile ferrite matrix.
What is dual phase steel used for?
Given their high energy absorption capacity and fatigue strength, cold-rolled Dual Phase Steels are particularly well suited for the manufacture of automotive structural and safety parts such as longitudinal beams, crossmembers and reinforcements.
Where are dual phase steels used?
Dual-phase steels are often used in the following automobile applications:
- DP300/500 Roof Outer, Door Outer, Body Side Outer, Floor Panel.
- DP350/600 Floor Panel, Hood Outer, Body Side Outer, Cowl, Fender, Floor Reinforcements.
- DP500/800 Body Side Inner, Quarter Panel Inner, Rear Rails, Shock Reinforcements.
What are the two phases that are present in dual phase steels?
The term dual phase steels, or DP steels, refers to a class of high strength steels which is composed of two phases; normally a ferrite matrix and a dispersed second phase of martensite, retained austenite and/or bainite.
What is secondary phase in dual phase steel?
This results in a microstructure consisting of a soft ferrite matrix containing islands of martensite as the secondary phase (martensite increases the tensile strength).
What is the secondary phase in dual phase steel?
How do you make martensitic steel?
A very rapid quench is essential to create martensite. For a eutectoid carbon steel of thin section, if the quench starting at 750 °C and ending at 450 °C takes place in 0.7 seconds (a rate of 430 °C/s) no pearlite will form, and the steel will be martensitic with small amounts of retained austenite.
How is martensitic stainless steel made?
They are hardenable by heat treatment (specifically by quenching and stress relieving, or by quenching and tempering (referred to as QT). The alloy composition, and the high cooling rate of quenching enable the formation of martensite. Untempered martensite is low in toughness and therefore brittle.
What is dual phase alloy?
What are dual phase high entropy alloys? Dual phase high entropy alloys are metallurgical materials which consist of a higher number of elemental components (4 or more) with the aim to form massive solid solutions exploiting the associated enhanced configurational entropy which stabilises them.
What is martensite and types?
MARTENSITE is a structure characteristic of quenched steels and consists of an aggregate of very minute needle-shaped crystals. By X-ray analysis, Westgren and others have found that the martensite has a body-centred cubic lattice, carbon atoms being present within the interspace of the lattice.
What is martensite composed of?
Properties. Martensite is formed in carbon steels by the rapid cooling (quenching) of the austenite form of iron at such a high rate that carbon atoms do not have time to diffuse out of the crystal structure in large enough quantities to form cementite (Fe3C).
What are the characteristics of a dual phase steel?
Dual-phase (DP) steels comprise a soft, continuous phase (a mechanically separable or visually identifiable portion of a structure) known as ferrite surrounding islands of a hard phase known as martensite (see Figure 1).
What kind of ferrite is in dual phase steel?
Relation between elongation and tensile strength of steels. Dual-phase (DP) steels are composed of ferrite and 5–20% of martensite, and their strength ranges from 500 to 1200 MPa. DP steels have a microstructure of mainly soft ferrite, with islands of hard martensite dispersed throughout.
Which is the secondary phase of DP steel?
DP steels are produced from low or medium carbon steels that are quenched from a temperature above A 1 but below A 3 determined from continuous cooling transformation diagram. This results in a microstructure consisting of a soft ferrite matrix containing islands of martensite as the secondary phase (martensite increases the tensile strength ).
What makes up the microstructure of a DP steel?
DP steels have a microstructure of mainly soft ferrite, with islands of hard martensite dispersed throughout. The strength level of these grades is related to the amount of martensite in the microstructure.