Pdf managing both strength and ductility in ultrafine. Pdf recent trends in producing ultrafine grained steels. Ultrafine grained structure formation in steels using. Combination of dynamic transformation and dynamic recrystallization for realizing ultrafinegrained steels with superior mechanical properties. Because the annealing temperatures are relatively low and the recrystallized structure is twophase, grain growth is restricted. Ultrafinegrained microstructures can be developed in a variety of alloy steels by coldworking followed by annealing in the. The term submicron structure refers to grain sizes between 100 nm and nm. Ultrafine grained steels by advanced thermomechanical processes and severe plastic deformations i. Low carbon ultrafine grained dual phase steels ubc. An important improvement of the fatigue strength was observed in the case of ultrafine grained steels, particularly for ufgs2. Request pdf ultrafine grained steels the modern low ultralow carbon bainitic steel ulcb is a highstrength, hightoughness and multiapplication steel. Dynamic fracture toughness of the ultrafine grained if steels was investigated as a function of grain size by miniaturized charpy impact test.
X80 pipeline steel produced by tmcp has high strength and high toughness with ultrafine grain microstructure. As this effect, however, has not yet been investigated in steels, fatigue experiments of an unalloyed medium carbon steel with a carbon content of 0. The effects of carbon content, alloying additions, initial starting structures and processing parameters like heating and cooling rate on the mechanical properties have. View table of contents for ultrafine grained materials ii. Here, the formation of ultrafine ferrite uff involves the dynamic transformation of a significant volume fraction of. Based on systematic description of research achievements of the project of ultrafine grain steels and their engineering applications, new theories of microstructural refinement and the newly developed technologies in production of high strength and high toughness steels are introduced. Thus, the tendency will be to machine these components adopting. Strain induced dynamic transformation and ultrafine surface grained steel one of the objectives of this project was to obtain ultra fine surface grained steels for plain and microalloyed lowc steels 0. Kim three types of ultrafine grained ufg low carbon steel were fabricated by equal channel angular pressing, and their microstructure and tensile properties were. Equal channel angular pressing of steels bcc, al alloys fcc and pure titanium hcp pages. We study orientation gradients and geometrically necessary dislocations gnds in two ultrafine grained dualphase steels with different martensite particle size and volume fraction 24 vol. Pdf recent progress in grain refinement of steels was overviewed. Pdf ultrafine grained steel by innovative deformation. Effect of vanadium addition on dynamic transformation during hot deformation of low carbon steels pages.
Surface integrity analysis when milling ultrafinegrained. Ultrafine grain formation during equal channel angular extrusion in an al. The formation of ultrafine grained steels is an area of intense research around the world. Effect of rolling reduction on ultrafine grained structure and mechanical properties of lowcarbon steel thermomechanically processed from martensite starting structure. Recent trends in producing ultrafine grained steels. Managing both strength and ductility in ultrafine grained steels article pdf available in isij international 488. Three types of ultrafine grained ufg low carbon steel were fabricated by equal channel angular pressing, and their microstructure and tensile properties were examined. A plain if steel and a padded if steel having various ultrafine grain sizes from 0. Raabe maxplanckinstitut fur eisenforschung, dusseldorf page 2. Dobatkin et al ultrafinegrained low carbon steels by severe plastic deformation tem contrast at the grain boundaries. Usually they are lowcarbon lowalloy materials with 1040 vol.
Effect of the pressing strain on the annealing behavior of ultrafine grained. These materials are currently the subject of extensive research efforts worldwide. Fabrication and tensile properties of ultrafine grained steels d. As another route the static recrystallisation of severely coldrolled martensite srm was utilized. After energetic research works since middle 1990s including big national projects in japan, ultrafine grained steels whose mean grain size is smaller than 1. Toughness of ultrafine grained ferritic steels fabricated. Processing and stability of ultrafine grained structures. Open access related content fatigue behavior of ultrafine. Alloy design is one of the first considered issues, while designing new steel with targeted mechanical properties. Ultrafine grained steels can be produced either by advanced thermomechanical processes or by severe plastic deformation strategies. Ultrafine grained steels managing both high strength. After energetic research works since middle 1990s including big national projects.
Ultrafine grained steels managing both high strength and. The microstructure coarsens and the toughness worsens at the coarse grained cg haz. Superplasticity is the ability of polycrystalline solids metals to achieve extremely high and uniform elongations from 100 to % when applying tensile stresses. Pdf microstructure control and mechanical properties of. Ultrafine grained steels with grain sizes below about 1 m offer the prospect of high. This paper provides an overview on obtaining lowcarbon ultrafine grained dualphase steels through rapid intercritical annealing of coldrolled sheet as improved materials for automotive applications. The biocompatibility of samples with the ultrafine grain structure obtained in the ecap process did not deteriorate in comparison with an austenitic 316l stainless steel in coarse. Pdf ultrafine grained steels with grain sizes below about 1. Corrosion behavior of ultrafine grained austenitic. Ultrafine grained steels managing both high strength and ductility to cite this article. Issue 1 structural ultrafine grained steels obtained by advanced controlled rollin 63 g name s315 s355 s420 s460 s500 s550 s600 s650 s700 table 1 chemical composition of thermomechanically rolled steels material number 1.
Salvatori on the wake of the advances in australia and japan in achieving even finer grain sizes, the european steel companies became particularly interested. The dynamic straininduced transformation dsit of ferrite from austenite in intense deformation at temperatures close to ar3 were applied to one cmn steel and several nb and nbti microalloy steels to obtain an ultrafine ferrite grain size. Dualphase steels dp steels consist of ferrite and a dispersed hard martensitic second phase in the form of islands. In general, the term ultrafine grain is used for average grain sizes between 1. High strength steel, ultrafine grain, dift, deformation induced ferrite. Full text pdf 8487k abstracts references128 citedby15 recent progress in grain refinement of steels was overviewed. A cciaio fabrication and tensile properties of ultrafine. Fatigue strength of ultrafine grained steels sciencedirect. Related content shape effect of ultrafinegrained structure on static fracture toughness in lowalloy steel tadanobu inoue, yuuji kimura and shojiro ochiai. This requires deformation within the ae 3 to ar 3 temperature range for a given alloy. Mechanical properties of the ultrafine grained ufg steels having mean grain sizes much smaller than 1 m were systematically shown from the. Ultrafine grained steels with grain sizes below about 1. Ufg ferritepearlite steels with or without vanadium exhibited ultrahigh strength, almost three times compared to that of their coarse grained counterparts.