Alloying effects on microstructure formation of dual phase steels. Multiphase steels in automotive industry thyssenkrupp steel. Irrespective of the chemical composition of the alloy, the simplest way to obtain a dual phase ferriticmartensitic steel is intercritical annealing of a ferriticpearlitic. Effect of welding current on weld formation, microstructure. Pdf in this paper, the development of dual phase steel from low carbon steel and mechanical properties have been studies. Applications dual phase 500 mpa tensile strength is intended primarily for exposed body panels doors, hoods and fenders. Dualphase steels are a new class of highstrength low alloy hsla steels characterized by a microstructure consisting of about 20% hard martensite. Rockwell hardness test and charpy toughness test for each dual phase steel specimen is conducted to compare its hardness and toughness with untreated medium carbon steel.
Increasing the volume fraction of hard second phases generally increases the strength. Microstructure and tensile properties in dual phase and trip. Multi phase steels is a central key fact in the automotive industry. The application of available two phase deformation models to dual phase steels is examined by testing them against available data published in the literature and an experimental highsiliconcontaining steel. The low and intermediate tensile strength, low yield ratio grades.
The initial microstructure can be fine ferrite pearlite structure or the tempered martensitic structure. 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. In this paper, the development of dual phase steel from low carbon steel and mechanical properties have been studies. Dual phase steels, design, formability, spot welding, laser welding, arc welding. Mechanical properties of the solidsolution ss treated steel and aged steel ag0.
Effects of the tempering temperature on mechanical. The martensite phase is substantially stronger than the ferrite phase. Highstrength lowalloy steels include many standard and proprietary grades designed to provide specific desirable combinations of properties such as strength, toughness, formability, weldability, and atmospheric corrosion resistance. Dual phase steel this information provides repair recommendations and general guidelines for steel classified as dual phase steel dual phase steel with a tensile strength up to and including 800 mpa, also known as dp. Depending on the strength class, the multiphase microstructure of. Influence of martensite composition and content on the. Dualphase alloys capable of high strength and ductility. Dual phase dp steel grade are a type of advanced high strength ahs steels that has been continuously developed for responding the requirements of high ultimate tensile strength with. Mechanical properties of bitumen quenched dual phase steel. Mechanical properties of bitumen quenched dual phase steel sifat mekanik bitumen lindap keluli dual fasa m.
High strength, high ductility, high formability dp800uc is a coldrolled, uncoated dual phase steel with a strength of approximately 800 mpa and a formability that makes it suitable for light deep drawn or crash formed components. Dual phase highductility steels dual phase highductility steels are an innovation of voestalpine in the field of ultralights. Both in dual phase and more pronounced in trip steels the retained austenite content plays a vital role in determining the formability. Dual phase steel was designed in o rder to reduce the weight o f used steel without loosing its benefits ferritic and bainitic are two kind of dual phase steels. Dual phase steels offer higher strength without reduced formability when compared to conventional high strength low alloy hsla steels and so thinner gauge dp sheet steel can be used to meet the same design requirements. We have added new grades which as well as offering high energy absorption and deformation resistance also display enhanced coldforming properties and allow substantial weight savings in the car body. Akinlabi abstract the mechanical properties of dual phase steel dpsduplex structureproduced by quenching in preheated bitumen. Pdf mechanical properties of bitumen quenched dual phase. Simply spoken the ferrite, which is a soft phase, gives a low yield point and the martensite, which is hard, gives the strength. They have better formability than the ferritepearlite steels of equivalent tensile strength and their strength ductility data fall on a separate curve figure 3 than that. The tensile properties of dual phase steel dpsduplex structureproduced by quenching in preheated bitumen have been investigated.
Dp ferrite plus martensite steels are produced by controlled cooling from the austenite phase in hotrolled products or from the twophase ferrite plus austenite phase. Dual phase steels dp steels are a part of the advanced high strength steel ahss family. High temperature mechanical properties of dual phase steels. General motors recommends the following when repairing or replacing this type of steel during collision repair.
Dual phase dp sheet steels have recently been used for automotive manufacturing to reduce vehicle weight and improve fuel economy. The material is often used for bodyinwhite structural and reinforcement components like pillar. Dual phase steels offer a good combination of strength and stampability as a result of their microstructure, in which a hard martensitic or bainitic phase is dispersed in a ductile ferritic matrix. For the steel industry, there may be a way out of the dilemma that has existed since people began processing metal. The effect of finishing rolling temperature on microstructure and mechanical properties of simn hotrolled dualphase steel had been studied when using large deformation in low temperature area. The controlled temperature, cooling rate annealing cycle in particular ensures that the dual phase microstructure is achieved and mechanical properties are reproducible. Dualphase 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. In general, these experiments suggest that the strength of dualphase steels increases with an increase in the volume fraction andor strength of the martensite phase. Using a new strategy in the development of steel, scientists are able to create alloys capable of both high strength and ductility. Dual phase steels are characterized by low yield strength, high work hardening, high tensile strength as well as high uniform and fracture elongation.
Room temperature stressstrain response spotted of three dp steels deformed isothermally in tension at 103 s, experiments vs. Hotrolled dp steel products are fabricated from the austenite phase. Dual phase steel so obtained is now tested and properties of the dual phase steel are evaluated. The effect of finishing rolling temperature on microstructure and mechanical properties of simn hotrolled dual phase steel had been studied when using large deformation in low temperature area. Effect of temperature in intercritical treatment on microstructure, tensile properties and hardness in dual phase st52 steel y. The methods of production of coated dual phase and trip steels were provided by tumuluru 2006a and are shown schematically in fig. The cr590t340ydp galvanized dual phase steel sheet used as an automobile manufacturing material not only has good corrosion resistance, but also high strength, which can effectively reduce the weight of the car body, and some research on resistance spot welding have been carried out 2426. Schematic shows islands of martensite in a matrix of ferrite. Dp steels consist of a ferritic matrix containing a hard martensitic second phase in the form of islands.
The objectives are thickness reduction of steel sheet, but superior safety demand. A multiscale approach to modeling formability of dualphase. Medium carbon steels intercritically heated at different temperatures and holding times were quenched in hot bitumen. Dual phase steels voestalpine steel division author. Dualphase steel dp steel is a highstrength steel that has a ferriticmartensitic microstructure. Dual phase dp steels dp steels consist of a ferritic matrix containing a hard martensitic second phase in the form of islands. Effect of silicon content on the microstructure and. Cp complex phase dp dual phase epa environmental protection agency fb ferriticbainitic fsv futuresteelvehicle ghg greenhouse gasses gpa giga pascal hsla highstrength, lowalloy hss highstrength steel if interstitialfree lca life cycle assessment analysis mpa mega pascal ms martensitic. Effect of fine grained dual phase steel on bake hardening. In this research, the stressstrain curves of two types of dual phase steels, namely ferriticbainitic and ferriticmartensitic steels with 0. Dp steels have a unique combination of outstanding elongation and work hardening rate, providing them superior ultimate tensile strengths when compared to traditional steels of same yield strength.
Their microstructure typically consists of a soft ferrite phase with dispersed islands of a hard martensite phase. The mechanical properties of dual phase steel dpsduplex structureproduced by quenching in preheated bitumen have been investigated. Dual phase steels data sheet grade availability arcelormittal offers a full spectrum of dual phase dp steels with tensile strength levels ranging from 500 to 1270 mpa. These steels are not considered alloy steels, even though their desired properties are achieved by the. Their microstructure typically consists of a soft ferrite phase with dispersed islands of martensite. This gives them not only good strain redistribution capability and thus stampability, but also finished part mechanical properties, including yield. Introduction the microstructure of dual phase steels consists of ferrite and martensite. The resulting material may also contain trace amounts of other phases such as retained austenite and bainite. Hosseinkhan nejad3 1 school of metallurgy and materials engineering, college of engineering, university of tehran, p. Multiphase steels is a central key fact in the automotive industry. Ferritemartensite dual phase steel is a lowtomedium carbon material with between 550% volume fractional martensite islands that are dispersed in a soft ferrite matrix.
Effect of initial microstructures on the properties of. A study of microstructure and phase transformations of medium carbon dual phase steels ersoy erisir1, oguz gurkan bilir1 1department of metallurgical and materials engineering, kocaeli university, 480kocaeliturkey abstract in this study, the suitability for producing dual phase steel from hot rolled medium carbon steel for mining. High strength dual phase dp steels have been increasingly used in car body structure for reducing weight and increasing safety performance. A study has been made of the mechanical properties of dual phase martensite plus ferrite structures produced when femnc alloys are quenched from the austenite plus ferrite phase field, so as to give a series of alloys with constant ferrite and martensite compositions but varying percent martensites. Mechanical properties of dualphase steels semantic scholar. Dual phase steels dp steels consist of ferrite and a dispersed hard martensitic second phase in the form of islands.
We at thyssenkrupp have widened our portfolio of coldrolled dualphase steels well beyond the conventional highstrength steels. The evolution of microstructure, chemical composition and mechanical properties hardness during this treatment was investigated. Weldability of a dualphase sheet steel by the gas metal arc. Dual phase steels are one of the important new advanced high strength steels ahss developed for the automotive industry. Dual phase steels microstructure 7585 vol% ferrite remainder mixture of martensite, lower bainite, retained austenite usually consists of more than 2 phases essentially just a low carbon steel thermomechanically processed for better formability than ferritepearlite steels of similar tensile strength. High temperature mechanical properties of dual phase. In contrast to classical dual phase steels, dual phase highductility steels feature significantly improved formability with respect to deep drawing. Dual phase steel is developed by intercritical annealing in order to improve the hardness and impact toughness. Dualphase steels,which have a microstructure of martensite dispersed in a ferritic matrix and provide a good combination of ductility and high tensile strength inclusionshapecontrolled steels,which provide improved ductility and throughthickness toughness by the small additions of calcium. The service properties of dual phase steels are guaranteed by manufacturing process control.
Medium carbon steels intercritically heated at different temperatures and holding times were quenched in hot. Pdf microstructures and mechanical properties of dual phase. Trip steel is produced by heating the steel into the intercritical temperature range for annealing so that dissolution of cementite occurs and formation of austenite starts. Mechanical properties and deformation mechanisms of a novel. Automotive worldwide product offer for us dual phasedual phase steels steels steels. It is found that the strength of a dual phase structure is dependent on the ferrite grain. Bake hardening process is widely applied for improving final mechanical properties of formed components by means of carbide precipitation and occurred cottrell cloud. In the past, some researches discussed about the effect of many factors on the properties of ferritemartensite dual phase fmdp steels. The tensile test properties of dual phase steels are governed by the martensite volume fraction, the martensite hardness and to a much smaller extent the martensite island diameter. Effect of temperature in intercritical treatment on. Usually they are lowcarbon lowalloy materials with 1040 vol.
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