64 research outputs found
Effect of Layer Construction on Tensile Deformation Behavior of Japanese-Sword-Type Steel Sheet
No full textEffect of Compressive Stress on Diffusional Transformation in 0.5%C Spring Steels With Different Austenite Grain Sizes
No full textEffect of Interface Morphology on Tensile Properties of Carbon Steel Sheet with Sandwich Structure
No full textEffect of Grain Size and Grain Orientation on Dislocations Structure in Tensile Strained TWIP Steel During Initial Stages of Deformation
No full textFriction Stir welding of Ultrafine Grained TWIP Steel
No full textMicrostructures and mechanical properties of ultrafine grained twinning induced plasticity (TWIP) steels, which were welded by both friction stir (FS) welding and conventional tungsten inert gas (TIG) welding, were studied. The ultrafine grained microstructure was successfully obtained by cold-rolling to a reduction in thickness of 88% and subsequent annealing at a warm temperature (620℃). Kikuchi line analysis in Transmission Electron Microscope (TEM) clarified that most of the grain boundaries in the annealed specimen are high angle grain boundaries whose misorientation angle is laｒger than 15°.The TIG welding of the ultrafine grained TWIP steel produces coarse grains whose mean grain size is 70 μm. on the other hand, the joint of the FS welded sample exhibits ultrafine grains with a high density of dislocations, and retains high hardness of the base metel. These results suggest that FS welding is an appropriate process for the joining of the ultrafine grained TWIP steels. The misrostructure evolution during the FSW was discussed with focus on the temperature dependence of the stacking fault energy of the TWIP steel. The tensile deformation of the parts of these joints were also examined at room temperature
Grain Size Dependence of the Flow Stress of TWIP Steel
No full textThe effect of grain size on the flow stress in TWinning Induced Plasticity (TWIP) steel was investigated via the X-ray diffraction (XRD) measurements of dislocation density. The results indicated that the hardening behavior of fine grained samples (mean grain sizes in the range of 2.1-3.8μm) can be described as typical dislocation interactions. However in coarse grained samples (mean grain sizes in the range of 4.7-38.5μm) where extensive mechanical twinning occurs, another strengthening mechanism is required. Consequently, the effect of grain size on the flow stress parameters of the proposed equation was considered and it was found that in the fine grained samples, the Holloman analysis can describe the hardening behavior. However, in coarse grained samples, a second hardening term due to the strengthening effect of mechanical twin boundaries needs to be added to the Holloman equation.</jats:p
Through-Thickness Microstructure and Strain Distribution in Steel Sheets Rolled in a Large-Diameter Rolling Process
No full textThe rolling condition for fabricating a low-carbon niobium-microalloyed steel sheet with an ultrafine-grained (UFG) structure was examined through rolling experiments and finite element analysis. A large-diameter rolling process was proposed to create a UFG structure. The rolling was conducted near the transformation point, Ar3, from austenite to ferrite. The Ar3 was measured at the surface and the center of the sheet. First, the through-thickness microstructure and equivalent strain distribution in a 1-pass rolled sheet 2.0 mm thick were examined. In the rolling experiments, the embedded pin method was employed to understand through-thickness deformation. The magnitude of the equivalent strain to obtain a UFG structure was estimated to be 2.0. Based on these results, the fabrication of a 2 mm UFG steel sheet by 3-pass rolling for an initial thickness of 14.5 mm was attempted by the proposed large-diameter rolling process
PS38 Effect of grain boundary precipitates on ductility at high speed deformation of Hadfield steel
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