Lattice rotation and stability of 22.5° ND rotated cube orientation in cold rolled polycrystalline AA 5182 aluminum alloy

AA 5182 aluminum alloy with a strong cube texture was cold rolled to different reductions at an angle of 22.5° to the prior rolling direction. The texture evolution at this new rolling direction was investigated by X-ray diffraction. The rotation paths and stability of the 22.5° ND rotated cube orientation were determined based on the variation in the three-dimensional orientation distribution function (ODF) with rolling reduction. The results show that most of the grains with the 22.5° ND rotated cube orientation are directly rotated to the β fiber along different rotation paths, but there are a few grains moving through the cube orientation to the β fiber. The {0 0 1}<1 1 0> oriented grains possess the lowest stability during rolling, and the stability increases as the initial orientation changes from the {0 0 1}<1 1 0> orientation to the {0 0 1}<1 0 0> orientation along the ₁ axis.     

Texture development in the cold rolling of IF steel

The development of deformation texture in ferrite has been measured in cold rolled IF steel. This has been compared, in a quantitative way, to the predictions of Taylor models—including those with relaxed constraints—and a finite element model with crystal plasticity constitutive laws. The finite element model gave much better prediction of the overall levels of orientation density but failed to predict the relatively high level of {0 0 1}1 1 0 texture which occurred at strains greater than about unity. That feature was predicted by relaxed constraint Taylor models. It is argued that that prediction is a coincidence, and either the finite element model cannot readily deal with the intragranular inhomogeneity of deformation in an adequate way, or that factors such as high-angle boundary migration may be important in the development of deformation texture.     

Textures and Magnetic Properties of Grain Oriented ElectricalSteel Produced by Cross Shear Rolling

Commercial grain oriented electrical steels were made by cross shear rolling (CSR) with a chosen mismatch speed ratio 1.1. Original sheets of 0.75 mm thick, which had been produced by conventional cold rolling and intermediate annealing were rolled to thickness from 0.35 mm to 0.15 mm, and followed by industry annealing. The deformation texture and the magnetic properties were measured. Results indicate that: in the condition of the CSR, the deformation texture of rolled sheet is generally similar to that of conventional rolled sheet; for sheets with the thicknesses from 0.35 mm to 0.25 mm, favorable deformation textures, mainly consisting of {111} <112>, are also found at subsudece layers, which may help produce sharp Goss texture, and after the final annealing, the magnetic properties of sheets are not lower than that of conventional rolled sheets     

Grain size effects on the tensile properties and deformation mechanisms of a magnesium alloy, AZ31B, sheet

The grain size dependence of the tensile properties and the deformation mechanisms responsible for those properties are examined for Mg alloy, AZ31B, sheet. Specifically, the Hall–Petch effect and strain anisotropy (r-value) are characterized experimentally, and interpreted using polycrystal plasticity modeling. {1 0 . 2} extension twins, {1 0 . 1} contraction twins, and so-called “double-twins” are observed via microscopy and diffraction-based techniques, and the amount of twinning is found to increase with increasing grain size. For the sheet texture and tensile loading condition examined, {1 0 . 2} extension twinning is not expected, yet the polycrystal plasticity model predicts the observed behavior, including this ‘anomalous’ tensile twinning. The analysis shows that the Hall–Petch strength dependence, of the polycrystal as a whole, is primarily determined by the grain size dependence of the strength of the prismatic slip systems.     

Texture development in cold rolled and annealed C-Mn-Si and C-Mn-Al-Si TRIP steels

Abstract

The texture of two transformation induced plasticity steels has been studied by means of crystallographic orientation mapping. Texture measurements were carried out on ferrite, bainite, and austenite. The polygonal ferrite and the bainite texture, both bcc, could be distinguished based on the image quality parameter of the electron backscattering diffraction measurement. Both bcc textures were very similar, the main difference being the more pronounced 111alpha ND ND=normal direction and 110alpha RD RD=rolling direction fibre textures in the polygonal ferrite. The fcc texture was a strong gamma deformation texture, characterised by the beta fibre. The presence of the alpha fibre confirmed the strong 110gamma ND direction, which was previously detected by means of X ray diffraction XRD. The measured fcc and bcc textures were used to calculate orientation distribution function transformations according the Bain, Kurdjumov-Sachs, and Nishiyama-Wasserman orientation relationships. The predicted cube component {001}gamma 100gamma, which was missing in the measured texture, of gammaret indicates a variant selection for the gammaalphaB transformation. In addition it was shown that crystallographic orientation mapping could be used to make reliable phase fraction determinations, which were previously based on the light optical microscopy of colour etched specimens. This also proves that XRD determination of gammaret is flawed owing to the strong texturing of all phases present in the microstructure.     

Comparative determination of the α/β phase fraction in α+β-titanium alloys using X-ray diffraction and electron microscopy

A comparison is made between the measured α/β phase fractions in Ti-6246 using X-ray diffraction (XRD) and electron microscopy. Image analysis of SEM and TEM images was compared to the phase fraction estimate obtained using electron backscattered diffraction, lab and high-energy synchrotron XRD. There was a good agreement between the electron microscopic and diffraction techniques, provided that the microstructural parameters of grain size and texture are estimated correctly when using quantitative Rietveld refinement.     

Application of nondestructive techniques for the prediction of elastic anistropy of a textured polycrystalline material

Effect of processing parameters including cold work and grain size on texture development in copper and 68:32 -brass thin sheets is investigated. The preferred orientation of grains (texture) is represented quantitatively by the orientation distribution function (ODF) as derived either by X-ray diffraction or by ultrasonic velocity measurements. The texture-induced elastic moduli are derived in the sheet plane at various orientations to the rolling direction. The predicted values of elastic moduli are compared with the mechanically measured ones. An attempt is made to empirically correlate ODF coefficients to the mechanically measured elastic modulus and plastic strain ratio (r-value). The sources of discrepancies such as the limitations of the measuring techniques and the models applied are discussed.     

3004铝合金晶格和织构演化的原位X射线衍射研究

为探究3004铝合金板材在拉伸变形过程中晶粒取向变化和晶格应变行为,明确两者在塑性变形过程中的竞争机制和作用,本文首次将原位拉伸方法用于铝合金织构演化和晶格应变行为的研究中,利用试验装置对3004铝合金进行定量应变拉伸,并在不同变形量下对样品进行X射线衍射物相和织构测试分析.实验结果表明:样品在弹性变形区晶格常数随应变...     

Stored energy in can body aluminium alloy after cold rolling and stress relieving

Abstract

Information on the stored energy after cold deformation and stress relieving would provide a greater understanding of the mechanism that controls the primary recrystallisation in deformed metals. Stored energy as a function of crystal orientation of 88% cold rolled and stress relieved can body aluminium alloy is calculated using the diffraction peaks from X-ray analysis. The obtained stored energy values are presented in the form of a stored energy distribution function on Euler angle space similar to the orientation distribution function. The stored energy along the β fibre that characterises the deformation texture and cube recrystallisation texture components is discussed in detail. A significant reduction of stored energy for the cube texture component after stress relieving is observed.     

Texture Characteristics of Thin Grain Oriented Silicon Steel Sheet Produced by Cross Shear Rolling

1. IntroductionSilicon steel is widely used as core materials oflarge transformers and large rotating machines. AfterWalter et al.11] reported that a difference in surface en. ?ergy induced tertiary recrystallization, very thin (lessthan 100 pm) grain oriented silicon steels producedby using tertiary recrystallization phenomena in vacuum have excellellt soft magnetic properties[2]. Nevertheless, since starting material using grain orientedsilicon steel sheet after secondary recrystallization i…     

Texture evolution and probability distribution of Goss orientation in magnetostrictive Fe–Ga alloy sheets

Texture evolution and the distribution of Goss orientation in polycrystalline Fe–Ga alloy were investigated as a series of rolling and subsequent annealing processes were used to develop highly textured rolled sheet. A dramatic change from the random nature of the as-rolled and primary recrystallized texture is observed when careful control of atmosphere and temperature during anneal leads to development of a sharp Goss orientation over up to 98 % of the surface of a sample during secondary recrystallization. In this work, grain boundary properties in local areas surrounding Goss grains are investigated and the evolution of Goss orientation is traced through the different stages of alloy processing using electron backscatter diffraction analysis. To evaluate the evolution of grains with Goss orientation, {011} grains are selected and separated from other texture components at each processing step and statistical analysis used to correlate the structural inheritance chain of Goss-oriented grains. The four processing stages considered are the alloy after hot rolling, the as-rolled alloy (i.e., after subsequent warm and cold rolling), the alloy after an initial anneal during which primary recrystallization occurs, and the alloy after final anneals in which secondary recrystallization with abnormal grain growth occurs. Analysis of Goss grain orientation probability distribution functions after primary and secondary recrystallization convincingly demonstrates that the orientation of the abnormally grown Goss texture that develops during secondary recrystallization is determined by the orientation of Goss components that develop during the primary recrystallization stage of alloy processing.     

热轧后退火对超纯铁素体不锈钢表面皱折的影响机理

以一种铌、钛双稳定化超纯Cr17铁素体不锈钢的热轧板和热轧退火板为初始材料,分别经相同的冷轧及退火处理,从显微组织演变、微织构演变的角度研究了热轧后退火对成品板表面皱折的影响机理.研究结果表明,与热轧后不退火相比,热轧后退火可使冷轧退火板的最大皱折高度和平均皱折高度分别降低37.0%、35.6%.热轧后退火有利于热轧板...     

Composition and orientation effects on the final recrystallization texture of coarse-grained Nb-containing AISI 430 ferritic stainless steels

Composition and orientation effects on the final recrystallization texture of three coarse-grained Nb-containing AISI 430 ferritic stainless steels (FSSs) were investigated. Hot-bands of steels containing distinct amounts of niobium, carbon and nitrogen were annealed at 1250 °C for 2 h to promote grain growth. In particular, the amounts of Nb in solid solution vary from one grade to another. For purposes of comparison, the texture evolution of a hot-band sheet annealed at 1030 °C for 1 min (finer grain structure) was also investigated. Subsequently, the four sheets were cold rolled up to 80% reduction and then annealed at 800 °C for 15 min. Texture was determined using X-ray diffraction and electron backscatter diffraction (EBSD). Noticeable differences regarding the final recrystallization texture and microstructure were observed in the four investigated grades. Results suggest that distinct nucleation mechanisms take place within these large grains leading to the development of different final recrystallization textures.     

AZ31镁合金室温拉伸微观变形机制EBSD原位跟踪研究

利用电子背散射衍射(EBSD)技术,原位跟踪AZ31镁合金轧制板材室温下沿轧向拉伸时的晶粒取向变化。对变形过程的滑移系和孪晶启动机进行分析。结果表明:变形过程主要由〈a〉基面和柱面滑移系开动而实现,晶粒取向无明显变化,大量〈a〉位错滑移的产生,使得变形后小角度晶界增加明显。晶粒中拉伸孪晶是试样在拉伸变形过程中产生的,而非在试样拉伸后的卸载过程中产生。     

FATIGUE CRACK GROWTH RATES IN Al–Li ALLOY, 2090. INFLUENCE OF ORIENTATION, SHEET THICKNESS AND SPECIMEN GEOMETRY

.The fatigue crack growth (FCG) behaviour of the aluminium–lithium (Al–Li) alloy 2090-T84 has been investigated from a series of constant amplitude FCG tests. The influence of in-plane orientation (L–T, T–L, L–T + 45°) and sheet thickness (1.6 and 6  mm) on the FCG rates for the rolled product has been examined. In general, the T–L orientation possesses superior FCG resistance for both thicknesses and the 6  mm thick sheet material showed marginally improved FCG resistance when compared to the 1.6  mm thick material, for all orientations. Closure-corrected FCG data suggests that much of the difference between the L–T and T–L orientation for the 6  mm thick sheet arises from differences in crack closure levels. When comparing the crack closure levels for C(T) and M(T) specimens, a significant difference is shown as ΔK increases. Fatigue crack growth rates for ΔK less than 15  MPa m were significantly higher in the M(T) specimens compared to the C(T) specimens. Compared with other factors examined the influence of specimen geometry appears to be a dominant factor.     

Experimental analysis and modeling of the anisotropic response of titanium alloy Ti-X for quasi-static loading at room temperature

This paper deals with the characterization and modeling of the deformation behavior of titanium alloy Ti-X^© under quasi-static conditions at room temperature. The material investigated is a 1.2 mm thick rolled sheet with a strong basal texture. Monotonic tensile, compressive and cyclic tests in various directions relative to the rolling direction were conducted in order to characterize the material behavior. Textural information was obtained from electron backscatter diffraction (EBSD) data. Strip drawing tests were also carried out. The experimental data has been extended to biaxial stress states using the visco-plastic self-consistent texture model (VPSC). The CPB06ex2 model Plunkett et al. (Int J Plast 24:847–866, 2008) was used to describe the yield surface. This model can describe the anisotropy and the tension-compression asymmetry. Distortional hardening was described taking account of the evolution of the model parameters. An extension of the model using the Armstrong and Frederick approach makes it possible to account for the Bauschinger effect during cyclic loading. There was a high level of correlation between the FE simulation and experimental data.     

Medium carbon steel deep drawing: A study on the evolution of mechanical properties,texture and simulations,from cold rolling to the end product

Medium carbon steels are mostly used for simple applications; nevertheless new applications have been developed for which good sheet formability is required. This class of steels has an inherent low formability. A medium carbon hot rolled SAE 1050 steel has been selected for this study. It has been cold rolled with reductions in the 7–80% range. Samples have been used to assess the cold work hardening curve. For samples with a 50 and 80% thickness reduction, an annealing heat treatment has been performed to obtain recrystallization. The material has been characterized in the “as received”, cold rolled and annealed conditions, using several methods: optical microscopy, X-ray diffraction (texture), Vickers hardness and tensile testing. The 50% cold rolled and recrystallized material has been further studied in terms of sheet metal formability and texture evolution during the actual stamping of a steel toecap that has been used to validate the finite element simulations.     

Texture control and the anisotropy of mechanical properties in titanium sheet

By means of three-dimensional crystallite orientation distribution function (CODF) analysis, the relationship between texture control processes and mechanical properties anisotropy in titanium sheet has been investigated. The formation and transition of cold-rolling texture, recrystallization texture and phase transformation texture are also discussed. The results show that, after being cold rolled unidirectionally and annealed, titanium sheet exhibits a strong anisotropy of mechanical properties due to the pyramidal textures (2 1 1 5) [0 1 1 ] and (1 0 1 3) [1 2 1 0]. After a cyclic phase transformation process coupled with cold rolling and annealing treatment, the recrystallization texture component (1 0 1 3) [1 2 1 0] is suppressed and [h k i l] 9∥ND transformation fibre texture (where ND is the sheet normal direction) are developed, which produce a well improved mechanical anisotropy. The cross-rolling process can create a basal type texture (0 0 0 2) 〈u v t w〉 or a near basal type texture, which leads to low level planar mechanical properties anisotropy but to relatively high normal plastic anisotropy (R value). This revised version was published online in November 2006 with corrections to the Cover Date.     

Strain hardening and orientation hardening/softening in cold rolled AA 5052 aluminum alloy

The tensile properties of cold rolled sheets were measured for the hot band and annealed hot band of AA 5052 aluminum alloy. The variation in yield strength with rolling true strain was used to represent the hardening rate of cold rolled sheets. The Taylor factor (M?) of cold rolled sheets in tension along the rolling direction was calculated based on the measured orientation distribution functions. The strain hardening and orientation hardening/softening produced by cold deformation were analyzed. The results show that the contribution to the hardening rate of cold rolled sheets comes largely from the deformed microstructure and partly from the texture change. For the annealed hot band the orientation softening occurs at strains below 0.5, while the orientation hardening occurs at strains over 0.5. For the hot band the dM?/dε value is always positive, indicating that orientation softening does not occur.