Topic
Bainite
About: Bainite is a research topic. Over the lifetime, 9520 publications have been published within this topic receiving 145305 citations.
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TL;DR: In this paper, the effect of pre-cold-working on the morphology of reversed arstenite was investigated by means of transmission electron microscopy and tensile test, and the alloy used is an Fe-18.08%Cr-8.65%Ni alloy.
Abstract: Metastable austenitic stainless steels undergo deformation induced transformation to bcc martensitic structure during cold-working. The martensite induced reverts to austenite at a relatively low temperature and this leads to the formation of ultra fine austenite grains of less than 1 μm in diameter. In this paper, the effect of pre-cold-working on the morphology of reversed austenite was investigated by means of transmission electron microscopy and tensile test. The alloy used is an Fe-18.08%Cr-8.65%Ni alloy. Since this alloy has metastable austenitic structure at room temperature, it almost transforms to lath-martensite by 50% cold-rolling. Further cold-rolling above 50% deforms transformed martensite itself, and results in the formation of dislocation-cell structure instead of lath-martensitic structure. The diffusional reversion of deformation induced martensite takes place at around 900 K and precold-working to lath-martensite not only promotes the reversion but also gives a large effect on the microstructure of reversed austenite: Reversed arstenite is characterized, in a specimen with 50% pre-cold-working, by the stratum structure of austenite laths and blocks, which looks like a lath-martensitic structure, while in a specimen with heavy pre-cold-working, by the structure of fine equiaxed grains. On the discussion of grain boundary strengthening in the former case, 0.2% proof stress depends not on the lath size but on the block size of reversed austenite.
124 citations
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TL;DR: It is shown that only the latter allow a reliable separation of the bainitic and ferritic phase, and the kernel average misorientation threshold value that separates both constituents is determined by an algorithm that searches for the smoothness of the boundaries between them.
Abstract: Bainite is thought to play an important role for the chemical and mechanical stabilization of metastable austenite in low-alloyed TRIP steels. Therefore, in order to understand and improve the material properties, it is important to locate and quantify the bainitic phase. To this aim, electron backscatter diffraction-based orientation microscopy has been employed. The main difficulty herewith is to distinguish bainitic ferrite from ferrite because both have bcc crystal structure. The most important difference between them is the occurrence of transformation induced geometrically necessary dislocations in the bainitic phase. To determine the areas with larger geometrically necessary dislocation density, the following orientation microscopy maps were explored: pattern quality maps, grain reference orientation deviation maps and kernel average misorientation maps. We show that only the latter allow a reliable separation of the bainitic and ferritic phase. The kernel average misorientation threshold value that separates both constituents is determined by an algorithm that searches for the smoothness of the boundaries between them.
124 citations
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TL;DR: In this paper, the results of the multi-stage compression tests and multiphase microstructures obtained as a result of the controlled multi-phase cooling were presented, and it was found that the hot workability of new generation of AHSS is very challenging due to high values of flow stresses required.
124 citations
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TL;DR: In this paper, a model to predict the austenite decomposition into ferrite, pearlite, bainite and martensite during arbitrary cooling paths for thin sheet boron steel is used.
124 citations
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TL;DR: In this article, the influence of the austempering temperature, chemical composition and partitioning on the nanostructure and mechanical behavior of high carbon (0.71 wt.%) bainitic-austenitic transformation-induced plasticity (TRIP) steels by atom probe tomography was investigated.
122 citations