Papers by Keyword: Transformation Texture

Abstract: Electron backscatter diffraction is a modern experimental method for local structure and texture investigation, which makes it possible to establish the presence and types of the various boundaries between the elements of the mesostructure such as low or high angle, special and interphase boundaries. Moreover, this technique can demonstrate the migration of boundaries during structural and phase transformations. This study estimated the possible spectrum of crystallographic misorientations of intercrystalline boundaries in additively manufactured titanium alloy Ti-6Al-4V using orientation microscopy and crystallographic calculations based on Burgers orientation relationship during β→α-transformation. The study has established that the boundaries between grains of α-phase are characterized by the misorientation angles of 11±2 °, 61±5 °, 89±3 °. The majority of high-angle boundaries are characterized by misorientation angles in the range of 57-65 °. The study also ascertained that the experimental spectrum of intercrystalline boundaries in the α-phase reveals the displacive nature of β→α-transformation in titanium alloys.

Abstract: A Theory is Developed for Martensite Variants that have Different Start Temperatures but Existin the same Steel. Themethod Enables the Volume Fractions of each Kind Ofmartensite to be Followed Asa Function of the Steel Temperature. the Problemis Relevant to the Calculation of Detail in Transformationtexture when Phase Changes Occur under the Influence of External Stress. it should Allow for the Firsttime, the Estimation of both the Location of Crystallographic Poles on a Stereographic Projection, Andthe Diffraction Intensity Associated with that Location. it is Found that the Increment of Transformationas a Function of Undercooling is Identical for all Variants, once Simultaneous Transformation Begins.Any Variance in the Absolute Fractions is due to the Differences in the Martensite-Start Temperature.

Abstract: Grain boundary texture evolution in case of two of the Zr based alloys (Zircaloy-4 and Zr-2.5\%Nb) was studied. In case of Zircaloy-4, grain boundary texture evolution during $\beta$ $\to$ $\alpha$ phase transformation was monitored. Direct evidence of variant selection during this transformation is presented. In case of Zr-2.5\%Nb alloy, considerable increase in $\alpha/\beta$ interfaces following Burger's orientation relationship was noticed with increasing annealing time at 700 \textdegree{}C.

Abstract: There is now a great deal known about the atomic mechanisms of solid–state phasetransformations, and this knowledge can be exploited to determine the distribution of crystalorientations. It is possible to estimate accurately, the crystallographic texture, transformationstrains and details of the microstructure, particularly in the context of steels. The concepts havenow been applied to design metallic alloys which compensate automatically for the residualstresses which develop in engineering components when they are cooled heterogeneously fromelevated temperatures. Such materials are now in commercial use and represent an innovationresulting directly from phase transformation theory.

Abstract: Quantitative prediction of transformation textures in steel becomes possible if a variant selection rule is taken into account, in which ferrite nucleating on austenite grain boundaries prefers to have orientation relationship with two neighboring austenite grains at the same time. The mathematical model of the variant selection rule is described and some examples of simulation in transformation textures in hot-rolled steel sheets are presented using the textures of retrained austenite and the misorientation distribution function method. An excellent agreement is attained between the predicted and experimental ferrite textures.

Abstract: We investigated the dendrite structures and the as-cast textures of low-carbon steel strips cast at different cooling rates in order to relate the δ-ferrite dendrite structure with the ferrite phase texture. Observations revealed that the orientation intensity of the texture component {111} was stronger than the texture component {001} in the as-cast steel strips obtained at different solidification cooling rates. These two texture components show a roof-shaped variation with the gradual decrease of the solidification cooling rate, reaching a maximum intensity at a cooling rate of about 2.0 K/s. This suggests that the solidification rate strongly influences the as-cast texture of low-carbon steel strips through changing the δ-ferrite dendrite structure.