Modeling texture development during cold rolling of IF steel by crystal plasticity finite element method

With the consideration of slip deformation mechanism and various slip systems of body centered cubic （BCC） metals, Taylor-type and finite element polycrystal models were embedded into the commercial finite element code ABAQUS to realize crystal plasticity finite element modeling, based on the rate dependent crystal constitutive equations. Initial orientations measured by electron backscatter diffraction （EBSD） were directly input into the crystal plasticity finite element model to simulate the develop- ment of rolling texture of interstitial-free steel （IF steel） at various reductions. The modeled results show a good agreement with the experimental results. With increasing reduction, the predicted and experimental rolling textures tend to sharper, and the results simulated by the Taylor-type model are stronger than those simulated by finite element model.＇Conclusions are obtained that rolling textures calculated with 48 { 110} 〈 111 〉＋ { 112 } 〈 111〉＋ { 123 } 〈 111 〉 slip systems are more approximate to EBSD results.

Influences of microstructure and texture on crack propagation path of X70 acicular ferrite pipeline steel

The aspects of two pipeline steels with different technologies were investigated by using transmission electron microscopy （TEM） and electron back-scattered diffraction （EBSD）. The microstructure presents a typical acicular ferrite characteristic with fine particles of martensite/austenite （M/A） constituent, which distributes in grains and at grain boundaries. The bulk textures of the pipeline steel plate are {112}〈110〉 and 〈111〉 fibers, respectively, and the {112}〈110〉 component is the favorable texture benefiting for drop weight tear test. Moreover, low angle boundaries and low coincidence site lattice boundaries are inactive and more resistant to fracture than high energy random boundaries.

Effects of microstructure and texture after thermomechanical treatments on corrosion behavior of AISI 321 pipeline austenitic stainless steel

In the present study,the effects of microstructure,grain size,and texture after thermomechanical processing on the corrosion behavior of AISI 321 austenitic stainless steel(ASS)were studied.The as-received,coarse-grained steel((35±3)μm)was subjected to 20%,50%and 90%thickness reduction through cold rolling at liquid nitrogen temperature,followed by annealing at 750,950 and 1050℃for 15 min.Recrystallization occurred after annealing at 750℃,and with the increasing of annealing temperature to 950℃and 1050℃,secondary recrystallization(abnormal grain growth)and grain growth were observed.The results showed that,after 20%thickness reduction,corrosion resistance increased significantly(21.1 kΩ·cm^(2))compared with the as-received condition(3.9 kΩ·cm^(2))due to the enhancement ofγ-fiber and the creation ofΣ3 boundaries.In contrast,the corrosion resistance decreased with the increasing of thickness reduction to 90%during rolling,but still depicted higher corrosion resistance compared with the as-received specimen.After annealing the 90%cold rolled(CR)specimens at 750 and 950℃,the corrosion resistance increased in comparison with the as-received sample as a result of the more uniform microstructure,appearance of Goss and brass texture components,and grain refinement.However,significant grain growth((112±76)μm)followed by a non-uniform structure was observed after annealing at 1050℃and resulted in the lowest corrosion resistance(1.3 kΩ·cm^(2)).

Significant effect of as-cast microstructure on texture evolution and magnetic properties of strip cast non-oriented silicon steel

In this study, two types of as-cast microstructure produced by strip casting were cold rolled and annealed to investigate the effect of initial microstructure on the textural evolution and magnetic properties of non-oriented silicon steel. The results indicated that the cold-rolled sheets of coarse-grained strip with pronounced {100} components exhibited stronger 入 fiber(<100>//ND) and weaker γ fiber(<111>//ND)texture as composed to the fine-grained strip with strong Goss({110}(001)) texture. After annealing, the former was dominated by η fiber(<001>//RD) texture with a peak at {110}<001)orientation, while the latter consisted of strong {111}(112) and relatively weak {110}(001) texture. In addition, a number of precipitates of size ～30-150 nm restricted the grain growth during annealing, resulting in recrystallization of grain size of ～46 μm in the coarse-grained specimen and ～41μm in the fine-grained specimen.Ultimately, higher magnetic induction(～1.72 T) and lower core loss(～4.04 W/kg) were obtained in the final annealed sheets of coarse-grained strip with strong {100} texture.

Microstructure and Texture Evolution of Fe-33Mn-3Si-3Al TWIP Steel on Strain

The microstructure and texture evolution of Fe-33Mn-3Si-3Al twinning induced plasticity(TWIP) steel were studied by the scanning electron microscope(SEM) and X-ray diffraction(XRD) at room temperature. After quasi-static tensile, the texture evolution of different strain was observed. It was shown that the Goss and Brass components increased within the strain range of less than 0.6. Whereas, the main components were decreased when the strain levels were greater than 0.6. This behavior was attributed to the low stacking fault energy(SFE) and was related to the strain energy of this high manganese steel. At high strain levels, the high strain energy may contribute to the Brass components transition to the A(rot-Brass) components.

Microstructure and texture evolution of nonoriented silicon steel during the punching process

The iron core of a motor is mainly manufactured from rolled nonoriented silicon steel using a punching process that leads to deformation and texture evolution at the cutting edge.According to this process,circular samples of nonoriented silicon steel were prepared by punching using blunt punch tools.In this work,two positions along the rolling and transverse directions at the cutting edge were analyzed.The main mechanisms of deformation for both positions are dislocation slip and formation of shear bands.These two mechanisms lead to similar texture evolutions for both positions.The dislocation slip leads to the formation of the{221}<uvw>component in the unbending area(200μm away from the cutting edge)and intermediate continuum-bent area.Additionally,the evolution of the texture from the{111}γfiber to the{110}fiber was observed at the extremity of the cutting edge with the formation of shear bands.

Microstructure ＆ texture evolution and magnetic properties of high magnetic-induction 6.5% Si electrical steel thin sheet fabricated by a specially designed rolling route

Electrical steel sheets with 6.5%(mas fraction) Si with good shapes and superior magnetic inductions were successfully produced by a specially designed processing route including ingot casting, hot rolling and warm rolling both with interpass thermal treatment, and final annealing. The sheets were of 0.2 mm and 0.3 mm thick over 140 mm width. A detailed study of the microstructural and textural evolutions from the hot rolling to annealing was carried out by optical microscopy, X-ray diffraction and electron backscattered diffraction. The hot rolled sheet characterized by near-equiaxed grains was dominated by the mixture of <001>//ND fiber(λ-fiber), <110>//RD fiber(α-fiber) and <111>//ND fiber(γ-fiber) textures owing to the partial recrystallization and strain induced boundary migration(SIBM) during the hot rolling interpass thermal treatment. The static recovery and SIBM during the warm rolling interpass thermal treatment result in large and elongated warm rolling grains. The warm rolling texture is dominated by obvious λ, Goss and strong γ-fiber textures. The application of the interpass thermal treatment during hot and warm rolling significantly enhances the impact of SIBM during annealing, which is responsible for the formation of the moderate λ-fiber, some near-λ fiber texture components and the obviously weakened γ-fiber texture in the annealed sheet, leading to a higher magnetic induction compared to the commercially produced 6.5% Si steel by chemical vapor deposition(CVD).

Effect of hot-band annealing process on microstructure,texture,and r-value of final sheets of ferritic stainless steel

In this paper,the effect of different annealing processes on the microstructure,texture,and formability of ferritic stainless steel was studied in detail.The results showed that the grain size in the final sheet was larger and the recrystallization texture was more uniform after the final recrystallization annealing of hot-rolled steel with continuous annealing than that without annealing or with batch annealing.In addition,the final sheet had a higher average r-value and the lowest planar anisotropy.

EBSD Investigation on Effect of Cooling Rate on Microstructure and Transformation Textures of High Strength Hot-rolled Steel Plates

The effect of cooling rate on the microstructure and transformation textures of high strength hot-rolled steels was investigated.Heat treated samples subjected to different cooling conditions were characterized by optical and scanning electron microscopes using orientation imaging microscopy（OIM）.The experimental results demonstrate that there is a significant effect of cooling rate on microstructures and textures resulting from phase transformation.Slow cooling rates lead to the appearance of the cube（001）[010],rotated cube（001）[110]/（001）[110],Goss（110）[001]and rotated Goss（110）[110]components.In contrast,textures developed at rapid cooling rates are preferably of Cu（112）[111],Br（110）[112],transformed Cu（113）[110]and transformed Br（332）[113]/（112）[131].These texture changes are attributed to the selective character of the phase transformation.The OIM technique was used to have a better understanding of the formation of phases and their relationship between microstructure and processing conditions.The volume fraction of micro-constituents resulting from phase transformation such as bainite,martensite and different types of ferrite,can be measured satisfactorily by this technique correlating image quality of EBSD patterns to specific phases.

Characterizing microstructure and texture after recrystallization annealing of Hi-B steel with simutaneous decarburization and nitriding

How to manufacture the high magnetic induction grain-oriented silicon steel（Hi-B steel）by the process featured with the primary recrystallization annealing was demonstrated,during which nitriding and decarburizing were simultaneously realized in laboratory.By the techniques of optical microscope,scanning electronic microscope and electron backscattered diffraction,both the microstructure and the texture in the samples were characterized.The samples had been subjected to nitriding to different nitrogen contents at two specified temperatures using the two defined microstructural parameters：the grain size inhomogeneity factorσ＊and the texture factor AR.The former is the ratio of the mean value to standard deviation of grain sizes;the latter is the ratio of the total volume fraction of the harmful textures to that of beneficial textures including {110}〈001〉.When the N content increased from 0.0055%to 0.0330%after the annealing at both 835 and 875°C,the resultant recrystallized grain size decreased butσ＊changed little;whilst the rise of annealing temperature from 835 to 875°C resulted in the increase in both grain size andσ＊.Moreover,either the injected N content or temperature had insignificant influence on the components of primary recrystallization texture developed during annealing.However,the increase of temperature led to the decreases in both intensity and volume fraction of{001}〈120〉and{110}〈001〉textures but increases in the{114}〈481〉andγfiber textures and the resultant decrease of AR.

Effect of heating rate on the recrystallization microstructure and property of ultra-low-carbon steel

In the present work,the microstructure,texture,and mechanical properties of a cold-rolled Ti-IF steel,after annealing at different heating rates,have been investigated.The results reveal that the mean grain size is gradually refined from 19.2 to 16.3 μ m as the heating rate increases from 4 to 50 ℃/s,but refined only slightly at heating rates of over 50 ℃/s.The recrystallization microstructure has a strong texture,which is a result of the sharpening of the favorable { 111 }//ND （normal direction） texture components or γ-fiber.With increasing heating rates,the peak value off（g） of γ-fiber decreases from 17 to 9.The yield and tensile strengths increase gradually as the heating rate increases from 4 to 50 ℃/s,but remain almost unchanged at heating rates of more than 50 ℃/s.The total elongation and uniform elongation increase gradually as the heating rate increases from 4 to 100 ℃/s,but decreases slowly for heating rates higher than 100 ℃/s.As the heating rate increases from 4 to 100 ℃/s,the plastic strain ratio of the steel decreases from 2.8 to 2.2; however,it increases to 2.9 for heating rates above 100 ℃/s.The strain hardening exponent remains unchanged at 0.27 in all annealing cycles.

Evolutions of texture and grain boundary plane distributions in a ferritic stainless steel

The grain size, textures and grain boundary plane distributions in a cold-rolled and annealed ferritic stainless steel were investigated by means of EBSD techniques. The results show that, following cold rolling with the thickness reduction of 85%, relatively low temperature （780℃） annealing brings an extremely sluggish grain growth and no grain texture develops when the annealing time varies from 5 min to 480 min. The free energy reduction of the system is mainly caused by the grain boundary plane re-orientation in addition to minor grain growth because the distributions of grain boundary planes are moderately preferred on { 100} according to the five parameter analyses （FPA） concerning the grain boundary plane characteristics. However, in the case of high-temperature （1 000 ℃） annealing, the average grain size does not increase until annealing time is prolonged to 90 min, after which extensive grain growth occurs and strong {100}（hkl） texture emerges whereas nearly random grain boundary plane distributions are observed. The free energy reduction of the system is most likely attributed to the selective growth.

Formation of Nuclei With {111}<110> and {111}<112> Orientations of IF Steel at Early Stage of Recrystallization Using EBSD Analysis

The excellent deep drawability of interstitial free steel （IF steel） is closely related to its texture formed during recrystallization. The nucleation process of cold rolled IF steel at the early stage of recrystallization was inves-tigated by electron back scattered diffraction （EBSD）. The characteristics of the microstructure after deformation and the orientation of nucleation were observed. The results show that the deformed microstructure with 80% reduction could be subdivided into two groups. These two types of microstructure were characterized by their orientation and internal local misorientations. The nuclei with γ-orientation preferred to form in deformed bands with γ-orientation and at the boundaries between deformed grains with different orientations. The recrystallized grains with { 111 } 〈 110〉 orientation appeared firstly in deformed matrix with {111} 〈112〉 orientation and consumed the matrix with {111 } 〈112〉 to grow up, while the recrystallized grains with {111} 〈112〉 orientation were observed secondly in de-formed matrix with { 111 }〈110〉 orientation and consumed matrix with { 111} 〈110〉 to grow up.

Effect of continuous annealing temperature on microstructure and properties of ferritic rolled interstitial-free steel

In this report,the microstructure,mechanical properties,and textures of warm rolled interstitial-free steel annealed at four different temperatures(730,760,790,and 820°C)were studied.The overall structural features of specimens were investigated by optical microscopy,and the textures were measured by X-ray diffraction(XRD).Nano-sized precipitates were then observed by a transmission electron microscope(TEM)on carbon extraction replicas.According to the results,with increased annealing temperatures,the ferrite grains grew;in addition,the sizes of Ti_4C_2S_2 and Ti C precipitates also increased.Additionally,the sizes of Ti N and Ti S precipitates slightly changed.When the annealing temperature increased from 730 to 820°C,the yield strength(YS)and the ultimate tensile strength(UTS)showed a decreasing trend.Meanwhile,elongation and the strain harden exponent(n value)increased to 49.6%and 0.34,respectively.By comparing textures annealed at different temperatures,the intensity of{111}texture annealed at 820°C was the largest,while the difference between the intensity of{111}<110>and{111}<112>was the smallest when the annealing temperature was 820°C.Therefore,the plastic strain ratio(r value)annealed at 820°C was the highest.

Microstructure and texture characteristics of ZK60 Mg alloy processed by cyclic extrusion and compression

The microstructure and crystallographic texture characteristics of an extruded ZK60 Mg alloy subjected to cyclic extrusion and compression(CEC) up to 8 passes at 503 K were investigated.The local crystallographic texture,grain size and distribution,and grain boundary character distributions were analyzed using high-resolution electron backscatter diffraction(EBSD).The results indicate that the microstructure is refined significantly by the CEC processing and the distributions of grain size tend to be more uniform with increasing CEC pass number.The fraction of low angle grain boundaries(LAGBs) decreases after CEC deformation,and a high fraction of high angle grain boundaries(HAGBs) is revealed after 8 passes of CEC.Moreover,the initial fiber texture becomes random during CEC processing and develops a new texture.

Influence of Hot Band Annealing and Cold Rolling on Texture and Ridging of 430 Stainless Steel Containing Aluminum

An approach to optimize the processing parameters to get superior ridging resistance and mechanical properties in commercial production of 430 ferritic stainless steel has been studied. Attention was also paid to improve productivity and energy saving without hampering the surface and mechanical property aspects of the material. Hot rolled coils annealed by slow cooling under insulated cover exhibit better ridging resistance than bell annealing treatment with a minor decrease in ductility. Soaking temperature prior to hot rolling has a significant effect on ridging resistance.

Characterization of Microstructure and Texture in Grain-Oriented High Silicon Steel by Strip Casting

Grain-oriented 4.5 wt% Si and 6.5 wt% Si steels were produced by strip casting, warm rolling, cold rolling, primary annealing, and secondary annealing. Goss grains were sufficiently developed and covered the entire surface of the secondary recrystallized sheets. The microstructure and texture was characterized by OM, EBSD, TEM, and XRD. It was observed that after rolling at 700 ℃, the 6.5 wt% Si steel exhibited a considerable degree of shear bands, whereas the 4.5 wt% Si steel indicated their rare presence. After primary annealing, completely equiaxed grains showing strong y-fiber texture were presented in both alloys. By comparison, the 6.5 wt% Si steel showed smaller grain size and few favorable Goss grains. Additionally, a higher density of fine precipitates were exhibited in the 6.5 wt% Si steel, leading to a ~ 30-s delay in primary recrystallization. During secondary annealing, abnormal grain growth of the 6.5 wt% Si steel occurred at higher temperature compared to the 4.5 wt% Si steel, and the final grain size of the 6.5 wt% Si steel was greater. The magnetic induction B8 of the 4.5 wt% Si and the 6.5 wt% Si steels was 1.75 and 1.76 T, respectively, and the high- frequency core losses were significantly improved in comparison with the non-oriented high silicon steel.

On the microstructure and texture evolution in 17-4 PH stainless steel during laser powder bed fusion: Towards textural design

Additive Manufacturing (AM) of metals allows the production of parts with complex designs, offeringadvanced properties if the evolution of the texture can be controlled. 17-4 precipitation hardening (PH)stainless steel is a high strength, high corrosion resistance alloy used in a range of industries suitable forAM, such as aerospace and marine. Despite 17-4 PH being one of the most common steels for AM, thereare still gaps in the understanding of its AM processing–structure relationships. These include the natureof the matrix phase, as well as the development of texture through AM builds under different processingconditions. We have investigated how changing the laser power and scanning strategy affects the microstructure of 17-4 PH during laser powder bed fusion. It is revealed that the matrix phase is δ-ferritewith a limited austenite presence, mainly in regions of the microstructure immediately below melt pools.Austenite fraction is independent of the printing pattern and laser power. However, reducing the timebetween adjacent laser passes during printing results in an increase in the austenite volume fraction.Another effect of the higher laser power, as well as additional remelting within the printing strategy, isan increase in the average grain size by epitaxial ferrite grain growth across multiple build layers andthe development of a mosaic type microstructure. Changes to the scanning strategy have significant impacts on the textures observed along the build direction, while (100) texture along the scanning directionis observed consistently. Mechanisms for texture formation and the mosaic structure are proposed thatpresents a pathway to the design of texture via AM process control.

Influence of the finish rolling temperatures on the microstructure and texture evolution in the ferritic stainless steels

The influence of the finish rolling temperature on the microstructure and texture evolution of Nb and B micro-alloyed ultra purified Cr17 ferritic stainless steels was investigated. The hot rolled bands were produced by conventional rolling process and the finish rolling at relatively low temperatures or ＂warm rolling＂. The microstructure was observed by optical microscopy, scanning electron microscopy and transmission electron microscopy, and X-ray diffraction was used to characterize the texture evolution processes. The results showed that as compared to conventional hot rolling process, the warm rolling has led to the refined and homogeneous microstructure and uniform recrystallization texture along γ-fiber in final sheets, indicating that the finish rolling at relatively low temperatures can be the effective way to improve significantly the formability of final sheets.

含铜抗菌不锈钢拉伸过程中的微观组织演变EBSD分析

目的研究含铜抗菌不锈钢拉伸性能,为工业生产中的成形工艺优化提供一定的理论依据。方法在拉伸应变分别为5%、15%、30%、45%、60%、75%以及最后拉伸断裂时应变为81%条件下,采用岛津AGS-100KN万能拉伸试验机对含铜抗菌不锈钢进行拉伸试验。通过扫描电子显微镜(SEM)、电子背散射衍射仪(EBSD)和透射电子显微镜(TEM)表征分析含铜抗菌不锈钢拉伸断裂后的断口形貌以及拉伸过程中的微观组织演变。结果含铜抗菌不锈钢抗拉强度最大值为587.523 MPa,应变最大值为81%。拉伸断口与拉伸方向呈45°开裂,呈杯锥状,断裂模式是韧性断裂。结论随着应变的增大,低角度晶界逐渐增多,高角度晶界与孪晶逐渐减少,GOS值逐渐增大,Goss织构、S织构和R织构含量逐渐减少,Brass织构含量逐渐增加,拉伸断裂后的体积分数为23.3%。在拉伸后期,Copper织构和Brass织构含量较多,在拉伸过程中起到整体稳定协调微观组织作用的S织构不断减少,随应变的增大,组织内部协调变形加快,变形程度快速增大,从而导致S织构向Copper织构和Brass织构转变,出现板条状马氏体,存在应变诱发马氏体相变。位错滑移、形变孪晶和形变诱导马氏体等多种变形机制的共同作用使含铜抗菌不锈钢具有良好的塑性。