Effect of thermomechanical treatment on the evolution of rolling and recrystallization textures in twin-belt cast AA5754 aluminum alloy

The relative importance of shear banding, particles, and grain size in determining the rolling and recrystallization textures of a twin-belt strip cast AA5754 aluminum alloy has been investigated. Various thermomechanical processing schedules have been employed that incorporate homogenization, warm and cold rolling, and intermediate anneals in various combinations prior to a final recrystallization treatment. Despite its inherent susceptibility, the alloy undergoes limited shear banding during rolling and displays a large random component of the deformation texture. The effect is most pronounced in the as-cast alloy subjected to cold rolling without any prior or intermediate heat treatments. This can be attributed to the denser distribution of particles, a greater scattering of the initial texture, and a relatively small grain size. Homogenizing prior to cold rolling promotes more extensive shear banding and accelerates the development of a strong rolling texture. A grain shape effect results in a prominent S component in the rolling texture at higher reductions, irrespective of the processing history of the material. In the heavily rolled as-cast alloy, the recrystallization texture is dominated by Cube and R components indicating the prevalence of oriented growth processes. However, homogenizing the as-cast alloy prior to cold rolling imparts a characteristic recrystallization texture with strong CH component, which is most likely due to selected growth of grains following particle-stimulated nucleation.     

Quantitative analysis of texture evolution of cold-rolled direct-chill-cast and continuous-cast AA5052 and AA5182 aluminum alloys during isothermal annealing

The as-received direct-chill-cast (DC) and continuous-cast (CC) AA5052 and AA5182 hot bands were preheated at 454 °C for 4 hours, followed by cold rolling to an 80 pct reduction in thickness. The texture evolution of these cold-rolled samples during isothermal annealing was investigated by X-ray diffraction. The variation in texture volume fractions with annealing time was quantitatively analyzed by using the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. The differences in recrystallization textures between the AA5052 and AA5182 alloys and between the DC and CC alloys were compared. It was found that the AA5052 alloy possessed a stronger cube recrystallization texture than the AA5182 alloy for the DC and CC materials. The recrystallization textures of the AA5182 alloy were affected strongly by the annealing temperature. As the annealing temperature increased, the cube recrystallization texture strengthened, whereas the R texture weakened. The annealing temperature had little influence on the recrystallization textures of the AA5052 alloy. The DC AA5052 and 5182 alloys also exhibited stronger cube recrystallization textures than the corresponding CC alloys. For the DC and CC AA5052 alloys, the n value in the JMAK-type equation increased with an increase in the annealing temperature, while the n values varied only slightly with the annealing temperature for the DC and CC AA5182 alloys.     

Evolution of Microstructure and Texture during Annealing of Aluminum AA1050 Cold Rolled to High and Ultrahigh Strains

The microstructure and texture of commercial purity aluminum (AA1050) have been investigated after cold rolling to von Mises strains of 3.6 to 6.4 followed by recovery and recrystallization during annealing. The evolution of structural parameters of the deformed microstructure, such as boundary spacing and fraction of high-angle boundaries (HABs), did not reach saturation in the given strain range. Recovery was accompanied by structural coarsening and by a decrease in the fraction of HABs. The coarsening rate increased with increasing strain prior to annealing. Recrystallization nuclei were found to form both in deformation zones around coarse particles and in recovered lamellar structures. The process of recrystallization in the present material can thus be characterized as discontinuous recrystallization. In recrystallized conditions, the average grain size was related to the grain orientation: the mean size of grains having orientations of the rolling texture was smaller than the size of grains with other orientations. The orientation dependence of the recrystallized grain size was more pronounced in the samples rolled to ultrahigh strains.     

Effect of Concurrent Precipitation on Recrystallization and Evolution of the P-Texture Component in a Commercial Al-Mn Alloy

The recrystallization behavior of a cold-rolled Al-Mn alloy was investigated, focusing on the effect of concurrent precipitation on nucleation and growth of recrystallization and the formation of the P- ( { 011 } á 111 ñ ) \left( {\left\{ {011} \right\}\left\langle {111} \right\rangle } \right) and ND-rotated cube ( { 001 } á 310 ñ ) \left( {\left\{ {001} \right\}\left\langle {310} \right\rangle } \right) texture components. It was observed that if precipitation took place prior to or simultaneously with recovery and recrystallization processes, i.e., by concurrent precipitation, this resulted in a delayed recrystallization, a coarse and elongated grain structure, and an unusually sharp P-texture component. The P-texture component sharpened with increasing initial cold rolling reduction, increasing initial supersaturation of Mn, and decreasing annealing temperature. The P- and ND-rotated cube nucleation sites have an initial growth advantage compared to the particle-stimulated nucleation (PSN) sites due to their 40 deg á 111 ñ \left\langle {111} \right\rangle -rotation relationship to the Cu component of the deformation texture. The boundaries between such sites and the surrounding matrix will be of the Σ7 type, and it is assumed that such highly perfect boundaries will be less affected by solute segregation and precipitation, resulting in early growth advantage. It was further observed that dispersoids present prior to cold rolling and annealing had a weaker effect on the recrystallized grain size and texture compared to concurrent precipitation, even though the average dispersoid density was higher in the pre-precipitation cases. The finer grain size was explained by the wider dispersoid free zones surrounding the large constituent particles compared to the concurrent precipitation cases. Subsequent growth of the nucleated grains, however, was more hindered due to the Zener drag, consistent with the higher dispersoid densities.     

Effect of Scandium on the Interaction of Concurrent Precipitation and Recrystallization in Commercial AA3003 Aluminum Alloy

In the current study, the effect of Sc addition on the interaction of concurrent precipitation and recrystallization in commercial AA3003 aluminum alloy was investigated using optical microscopy, scanning electron microscopy, and transmission electron microscopy. In case of AA3003 alloy, which was cold rolled to a true strain of 2.20 and heated at a heating rate of 150 K/s, the onset of precipitation and ending of recrystallization are signified by the critical temperature, T _C ~740 K (467 °C). There is a change in the shape of the recrystallized grains from pancake-like to equiaxed shape, as the annealing temperature increases greater than T _C. In case of AA3003 alloy microalloyed with 0.4 wt pct of Sc, the high no. density precipitation of coherent Al₃Sc precipitates always occurs before recrystallization because of the small nucleation barrier and high rate of decomposition. This leads to extremely coarse pancake-like recrystallization grains with high fraction of low-angle grain boundaries in the entire annealing temperature range, even at a high brazing temperature of 883 K (610 °C).     

高性能取向硅钢的工业化生产研究

采用光学显微镜、X射线衍射仪等分析了宁波钢铁有限公司生产的取向硅钢不同工序下的组织及织构演变规律.结果 表明:铸坯经过热轧后,沿着厚度方向组织不均匀;一次冷轧并经脱碳退火后,组织由条状纤维状变成等轴状的初次再结晶晶粒,初次再结晶平均晶粒尺寸为18.17 μm,织构主要以α织构和γ织构为主;在二次冷轧后,晶粒再次被压缩,转变为纤维状,织构主要为γ织构;经过高温退火后,发生二次再结晶,晶粒异常长大,晶粒尺寸达到厘米级,织构成分为单一且锋锐的Goss织构.     

Initial stages of recrystallization in aluminum of commercial purity

In commercial aluminum with a purity of 99.4 pct, the formation and growth of recrystallization nuclei were studied by techniques such asin-situ annealing in a high voltage electron microscope, transmission electron microscopy and light microscopy. Sample parameters were the initial grain size (370 and 19 microns) and the degree of deformation (50 and 90 pct reduction in thickness by cold-rolling). It was found that the initial grain boundaries and high angle boundaries within the original grains are preferential sites for recrystallization nuclei, and that the effect of such sites is enhanced by the FeAl₃ particles present in the commercial aluminum as impurities. The nucleation temperatures determined by high voltage electron microscopy and transmission electron microscopy decrease markedly when the initial grain size is decreased both after 50 and 90 pct cold rolling; a less pronounced temperature decrease is obtained by increasing the degree of deformation. The size of the recrystallization nuclei, the recrystallization temperature and the recrystallized grain size are reported for the four sample states, and finally the structural and kinetic observations are discussed.     

薄带连铸取向硅钢Goss晶粒二次再结晶过程的研究

研究了双辊薄带连铸Fe- 3%Si取向硅钢薄带在冷轧后二次再结晶过程中Goss晶粒的演化过程。结果表明：薄带连铸流程可以固溶较多的抑制剂元素，并且无需通过“γ→α”相变控制AlN的析出。铸带经过两阶段冷轧变形和高温退火后，可以获得完善且位向准确的Goss晶粒，B8值达到1. 92T以上。高温退火升温过程中，在抑制剂的作用下基体晶粒尺寸基本稳定，Goss晶粒在1035～1060℃范围内发生异常长大。长大方式为位向准确的Goss二次晶粒快速发生异常长大，吞并基体中稳定的初次晶粒，而后快速发生异常长大的二次晶粒继续吞并发展缓慢的Goss二次晶粒和一些尺寸较大的初次晶粒，最终完成全部二次再结晶过程。     

Effect of intermediate heat treatment on microstructure and texture evolution of continuous cast Al-Mn-Mg alloy sheet

The microstructure and crystallographic texture evolution of continuous-cast, hot-rolled Al-Mn-Mg alloy sheet during cold rolling and subsequent annealing was investigated. All specimens cut from the as-received sheet were cold rolled and subsequently annealed, with some of these specimens receiving an intermediate heat treatment (IHT) prior to cold rolling. It was found that the degree of deformation and temperature of the annealing had a significant effect on the final grain size and texture of the sheet specimens, respectively. Furthermore, the IHT altered the development of the microstructure and texture of the final sheet specimens when compared to similarly produced specimens without it. For the sheet specimens without the IHT, a severely elongated grain structure was found in which the texture was dominated by a strong P orientation {011}<566>, despite the fact that the specimen was completely recrystallized. In contrast, specimens receiving the same cold rolling and annealing conditions but with the IHT had an equiaxed grain structure with a sharp Cube orientation {001}<100>. Counterbalancing the deformation textures from rolling with a sharp Cube orientation from annealing may lead to reduced earing behavior of CC Al-Mn-Mg alloy sheet products during deep drawing applications.     

冷轧压下率对无抑制剂取向硅钢初次再结晶退火的影响

对无抑制剂取向硅钢不同压下率下初次再结晶退火后的显微组织、宏观织构和微观织构进行了研究.结果表明,冷轧板织构主要为α取向线{001}＜110＞、{112}＜110＞和{111}＜110＞织构以及γ取向线{111}＜110＞织构.初次再结晶退火后,α取向线织构减弱,织构主要为γ取向线{111}＜112＞织构.随冷轧压下率的增加,冷轧和初次再结晶织构强度增加.当压下率为88％时,初次再结晶退火后 Goss 织构和{111}＜112＞织构强度最高,最有利于发生二次再结晶.EBSD 分析显示,Goss 取向晶粒大多与{111}＜112＞取向晶粒相邻.提高冷轧压下率,Goss取向晶粒和{111}＜112＞取向晶粒都增加,Goss 取向晶粒偏离理想取向角度减少.     

Effect of the Heat Treatment on the Cube Recrystallization Texture of Al-Mn-Mg Aluminum Alloy

The evolution of the recrystallized structure and texture of a cold-rolled Al-Mn-Mg alloy with different heat treatments was studied. The alloy with dual-heat treatments at 872 K and 644 K (599 °C and 371 °C) exhibited fast recrystallization and had coarser recrystallized grains and stronger cube texture than the alloy with single-heat treatment at 872 K (599 °C). The differences in microstructures and textures were attributed to the precipitation state. Large particles formed during annealing at 872 K (599 °C) played a randomizing effect on the total recrystallization texture, while smaller particles formed during annealing at 644 K (371 °C) not only enhanced recrystallization of the cold-rolled sheets, but also caused formation of coarse, recrystallized grains with a strong cube texture. The evolution of the coarse grains was due to nucleation of cube-oriented grains.     

Comparison of the texture evolution of direct chill and continuous cast AA5052 hot bands during isothermal annealing

As-received commercial direct chill cast (DC) and continous cast (CC) AA5052 hot bands were isothermally annealed at different temperatures. The variations of electrical resistivity, hardness, microstructure, and texture of these hot bands during annealing were examined. Texture was investigated by X-ray diffraction. The variation in texture volume fractions with annealing time was quantitatively analyzed by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. The orientation maps of the partially and fully recrystallized samples were characterized by electron backscattered diffraction (EBSD). It was found that electrical resistivity of the CC AA5052 hot band was higher than that of the DC AA5052 hot band. The electrical resistivity of CC AA5052 decreased more significantly than that of DC AA5052 during isothermal annealing. The DC AA5052 hot band was more easily recrystallized than CC AA5052 hot band during annealing. After complete recrystallization, DC AA5052 hot band possessed a stronger cube texture than the CC AA5052 hot band. The texture evolutions of DC and CC AA5052 can be expressed quantitatively by the JMAK equation after the volume fractions of the texture components are calculated by an improved integration method. Annealing temperature had an influence on the n values in the JMAK-type equations. The n values are small at low annealing temperatures.     

Sources of recrystallized grains and their contributions in recrystallization of an AA3104 aluminium alloy

The hot rolled AA3104 ingot was cold rolled to 40%, 66%, 80% and 90% reductions. The cold rolled sheet was subsequently recrystallized at two different annealing temperatures of 573 K and 773 K. The bulk texture developments, both deformation and subsequently after recrystallization, were measured by X-ray ODFs (orientation distribution function), while recrystallized (and in few cases the partially recrystallized or recovered) samples were studied by SEM-EBSD (scanning electron microscope based electron backscattered diffraction).     

α相含量对AA3104铝合金热轧组织及退火行为的影响

通过对AA3104铝合金均匀化时间的控制,获得α相含量分别为18%和68%的初始材料,并对其进行轧制温度约为480℃~420℃、形变量为95%的热轧形变。利用扫描电镜(SEM)及能谱仪(EDS)对第二相含量、平均尺寸以及尺寸分布进行定量表征。利用显微硬度测定了不同α相含量热轧板的再结晶温度,利用X射线衍射技术(XRD)对再结晶前后织构进行研究,并对比分析织构差异。结果表明:热轧后,α相含量为18%的第二相粒子中尺寸接近5μm的粒子数量较少,其完全再结晶温度约为380℃,且立方织构的含量低;α相含量为68%的试样热轧后含有更多尺寸接近5μm的第二相粒子,其完全再结晶温度约为340℃,且立方织构含量较前者高,结果表明含有第二相粒子的AA3104铝合金热轧组织及退火行为与α相含量有关。     

退火温度对超薄取向硅钢织构及磁性能的影响

 为了研究中/高频用超薄取向硅钢制备工艺中退火温度对组织、织构及磁性能的影响,以商用0.27 mm规格无底层取向硅钢成品板为原料采用初次再结晶法制备了0.08 mm厚的超薄取向硅钢。系统研究了800~1 000 ℃温度范围内退火对超薄取向硅钢退火组织、织构及磁性能的影响。结果表明,过渡带中的η取向({0kl}<100>)与相邻形变基体呈大角度取向差晶界,再结晶开始时,η取向组分优先在过渡带边界“弓出”形核;随着退火温度升高,再结晶平均晶粒尺寸增大,{114}<481>等非η取向晶粒尺寸优势愈发明显,η组分体积占比降低,晶粒尺寸均匀性变差;稍低温退火时超薄取向硅钢综合磁性能较好,退火温度为800 ℃时,磁感应强度B₈₀₀=1.82 T,铁损P_1.5/400=11.66 W/kg,获得本试验条件下最佳综合中频磁性能。     

Static Recrystallization Kinetics and Crystallographic Texture of Nb-Stabilized Ferritic Stainless Steel Based on Orientation Imaging Microscopy

In the present study, Nb-stabilized ferritic stainless steel was prepared with annealing (430-A) and without annealing (430-NA) annealing, and the microstructure of the resulting samples was examined. The steel was then subjected to cold rolling and isothermal annealing in order to analyze its recrystallization kinetics and texture evolution. Microstructural characterization was performed by scanning and transmission electron microscopies. Recrystallization kinetics were evaluated by measuring the microhardness of the samples, and analyzing their kernel average misorientation and grain orientation spread via electron backscatter diffraction. The Avrami exponent data revealed that one-dimensional grain growth occurred owing to the migration of high-angle grain boundaries. The mean activation energies for recrystallization for 430-NA and 430-A was found to be 365 and 419 kJ mol⁻¹, respectively. The recrystallization texture was influenced by oriented nucleation and selected growth mechanisms, as well as by the Nb carbonitride distribution and grain boundary energy. The recrystallized and growing grains with the {554}〈225〉 orientation showed a dimensional advantage over the other recrystallized components. The coincident site lattice boundaries were attributed to the progression of recrystallization since the CSL numeric fraction increased as the temperature increased. The {554}〈225〉 component was associated with the ∑19a boundary, which exerted a significant control on the selective growth during the recrystallization.

     

Microstructure and texture evolution during recrystallization of low-carbon steel sheets

Aluminum killed low-carbon steel sheets were cold rolled at different reduction ratios and annealed using different temperatures and holding time.The Vickers hardness was examined.The results show that when cold rolling reduction ratios increase from 40% to 81%,recrystallization temperatures decrease from 602°C to 572°C during 4hisochronal annealing,as well recrystallization holding time decreases from 117 min to 5min during isothermal annealing at 610°C.All recrystallization temperatures and holding time can be calculated using the annealing experiment results.Microstructure was examined through electron backscattered diffraction(EBSD).The results show that as rolling direction preferentially grows,equiaxed grains grow into cake-type during recrystallization.Cake-type grains are more beneficial to obtaining ideal111//ND(normal direcrtion)orientation texture.{111}orientation grains nucleate and grow up preferentially.Deformation grains of{111}110orientations grow into new recrystallization grains of{111}123and{111}112during recrystallization.Texture formation can be explained by directional nucleation.     

Development of recrystallization textures in 0.08%C steel

The present work investigates the effect of cold deformation on the evolution of microstructure and textures during recrystallization in 0.08%C steel. The cold rolling texture consists of partial α-fiber (RD//〈110〉) and complete γ-fiber (ND//〈111〉) along with Goss ({110}〈001〉) and cube ({100}〈100〉}) texture components. The sharpness of α-fiber, γ-fiber and cube component increases with the increase in rolling reduction from 70 to 85% while that of Goss component decreases. After recrystallization (750 and 800°C), the textures were composed of α and γ-fiber along with significant Goss components. The strength of γ-fiber decreases after annealing. The presence of Goss component in recrystallization textures is attributed to preferential nucleation in {111}〈112〉 type deformed grains.     

卷取温度对高强IF钢再结晶及织构的影响

为了研究卷取温度对高强IF钢250P1罩式退火再结晶规律的影响,采用氮气炉加热模拟罩式退火工艺,研究了高温及低温卷取工艺下含磷高强IF钢250P1冷轧板再结晶规律;采用X射线衍射仪对700 ℃模拟退火板及罩式退火成品板进行了织构分析,并对成品板金相组织进行了观察。结果表明,低温卷取冷轧板再结晶温度约为675 ℃,高温卷取冷轧板再结晶温度约为700 ℃;低温卷取退火板具有较高强度的{111}有利织构、较高的{111}/{100}比值以及r值,成品板的饼形晶粒更大。     

铌对低温取向硅钢初次再结晶行为的影响

以含铌取向硅钢铸坯低温加热制备高磁感取向硅钢为研究目标,通过研究铌对低温取向硅钢初次再结晶行为的影响,达到获得有利于二次再结晶发展的初次再结晶组织目的,采用OM和EBSD技术主要对比了 0.055％铌和不含铌对低温取向硅钢中间退火板的初次再结晶组织、织构和晶界特征的影响.结果表明,铌的加入,使硅钢基体中形成了细小弥散的...