Correlation Between Pre-annealing Temperature and {110}〈001〉 Annealing Texture in C- and Al-Free Fe-3 Pct Si-0.1 Pct Mn-0.002 Pct S Electrical Steel

In C- and Al-free electrical steel, the increase in primary grain size with increasing pre-annealing temperature causes the transition in annealing texture after final annealing from {110} + {100} to {110}. The strip pre-annealed at 1073 K (800 °C) shows a low magnetic induction B₈(T) of 1.784 T after final annealing. The strip pre-annealed at 1223 K (950 °C) shows a sharp {110}〈001〉 Goss texture, producing a high magnetic induction B₈(T) of 1.914 T comparable to that of the conventional electrical steels.     

稀土铈对2.9%Si无取向硅钢磁性能的影响

 摘 要： 为了获得磁性能优良的高牌号无取向硅钢,系统地研究了稀土铈对2.9%Si无取向硅钢中夹杂物的变质及粗化,退火板的组织、织构及磁性能的影响规律。结果表明：钢中添加适量（质量分数0.005 5%）的铈能使夹杂物聚集粗化,最终使成品再结晶晶粒尺寸增大,有利织构组分{100}和{110}面织构增多,不利织构组分{111}面织构减少,磁性能达到最佳。但是当铈添加过量（质量分数0.019%）时,其作用反而相反。     

Effect of silicon content and carbon addition on primary recrystallization of Fe-3 pct si

A study was made on the effect of the increase of silicon content and the addition of carbon on the primary recrystallization of silicon steel sheet containing MnS and AlN as inhibitors. The increase of silicon content led to the reduction of the size of primary grains and the intensity of {110} that is considered to represent the amount of {110}〈001〉-oriented nuclei, to the gain of the size of precipitates, and to the coarse dispersion of the precipitates. The carbon addition promoted primary recrystallization and decreased the size of primary grains. From the points mentioned earlier, the increase of silicon content is considered disadvantageous, and the carbon addition is advantageous to the secondary recrystallization of the {110}〈001〉 texture.     

Effect of copper precipitation on the development of recrystallization textures through continuous annealing of low-carbon sheet steel

The development of {111} recrystallization textures in 0.5 pct and 1 pct Cu-containing steels through a simulated continuous annealing cycle has been investigated. A low-carbon content of 0.05 pct compared with extra low-carbon content of 0.005 pct accelerated the precipitation of ε-Cu by preaging prior to cold rolling, and a nickel content up to 0.95 pct gave the adverse effect. Pole intensity ratio, I₂₂₂/I₂₀₀, of the cold rolled and continuous-annealed sheet depended more strongly upon the distribution density of ε-Cu particles than upon the amount of carbon in solid solution. The optimum dispersion of e-Cu precipitates for producing a strong {111} texture was about 300 particles per μm³ in distribution density, and 20 to 30 nm in particle size. Also, it was suggested that through continuous annealing by utilizing the effect of prior precipitates such as ε-Cu, a high strength, dual-phase steel with a highr-value could be produced. Formerly Graduate Student, Kyushu University     

Effects of precipitates on grain size and mechanical properties of AZ31-x% Nd magnesium alloy

The effects of precipitates on grain size and mechanical properties of as-cast AZ3 1-x%Nd magnesium alloy were investi- gated, and the affecting mechanism was also discussed. The results indicated that Al2Nd phase, AlllNd3 phase and a few AI-Mn-Nd-Fe phase were furmed when adding 0.38 wt.%-1.46 wt.% Nd into AZ31 melt, coarse AI2Nd transformed into Al11Nd3 gradually with the increasing of Nd content. Due to structure and size transformation and content increasing of AI-Nd phase, the grain size of AZ31-x% Nd alloy increased firstly, and then decreased with the increment of Nd content. After reaching a minimum value, once again it rose up, provided that Nd content was further increased. The tensile property reached its optimal value when the adding amount of Nd content was 1.05 wl.%, however, adding excessive amount of Nd deteriorated both ultimate strength and elongation ofAZ31 alloy.     

含Nb低温取向硅钢热轧板织构及析出物分析

分别采用电子背散射衍射技术(EBSD)、JEM-2100型透射电镜(TEM)研究了Nb元素对取向硅钢热轧板织构和析出物的影响。结果表明:取向硅钢添加Nb元素以后,热轧板中晶粒尺寸相对细小、Goss织构({110}001)含量更高、位向更精准,而且出现了传统取向硅钢热轧板中很难形成的γ取向线织构({111}112和{111}110);透射电镜分析结果显示含Nb实验钢中析出相尺寸更细小而均匀,析出相除了MnS、AlN,还有NbCN,析出相含量增多,同时Nb的加入对细化其他析出物有积极的作用;含Nb取向硅钢中析出相的尺寸越小和体积分数越大,则析出相的抑制力也就越大,从而为形成的γ取向线织构和更高含量的Goss织构提供了有利的条件。     

Inclusions for Ultra-pure Ferritic Stainless Steels Containing 21% Chromium

As stabilizing elements added into ultra-pure ferritic stainless steels, niobium and titanium react with carbon and nitrogen to form carbonitrides and have great effects on the ratio of equiaxed zone and the grain size of solidification structure of ingots, which remarkably affect the quality of cold-rolled sheets. Combined with thermodynamic calculation, style and precipitation progress of inclusions in ultra-pure ferritic stainless steels were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The results indicate that the inclusions are mainly Ti-Al-N-O system inclusions in ultra-pure ferritic stainless steels. Al₂O₃ starts to precipitate firstly and then TiO_x and TiN precipitates sequently. The inclusions are mainly single TiN particles and complex inclusions with Al₂O₃-Ti₂O₃ as cores and covered with TiN under the condition of 0.31% titanium addition and mainly Al₂O₃ under the condition of 0.01% titanium addition. A few (Nb, Ti) N particles precipitate because of no enough titanium to react with nitrogen when titanium addition is 0.01%. In addition, fine Nb(C, N) particles with size of less than 500 nm precipitate at relatively low temperature.     

铜含量对TSCR工艺生产取向硅钢热轧织构的影响

 取向硅钢热轧板中织构梯度对发展完善的二次再结晶十分关键,通过添加Cu可以显著降低取向硅钢板坯加热温度,从而影响热轧板织构分布。本文利用X射线衍射仪,分析了实验室模拟薄板坯连铸连轧（TSCR）工艺的3种不同Cu含量的取向硅钢热轧板织构。结果表明：不同Cu含量热轧板表面到厚度1/4处均为弱的热轧织构,热轧板心部主要为{100}面织构;Cu含量约在0.4%时,热轧板次表层的{110}<001>织构比例最高,而热轧板心部的{100}<110>织构比例最低;Cu含量对热轧织构中{114}<110>和{001}<100>织构发展有显著影响。     

Precipitation Behavior and Textural Evolution of Cold-Rolled High Strength Deep Drawing Dual-Phase Steels

Low-carbon Cr-Mo micro-alloyed deep drawing dual-phase steels were designed in laboratory. As the microstructure and texture evolution in hot-rolled strips and annealed sheets were investigated using SEM, TEM and XRD technologies, the attribution of solute Mo and MoC particles to DP sheets' drawing capacity was investigated. The precipitation thermodynamics were also calculated by Thermo-calc software. Results show that the precipitates in hot-rolled strips mainly are MoC, AlN and MnS, and with the increase of Mo-addition, finer and denser MoC particles precipitated in matrix and along grain boundaries of ferrite more easily. Weak textures are shown in the hot-rolled strips, and {112}<110> and {223}<110> components tend to be stable in subsequent cold rolling process. During annealing, on one hand, the development of <111> // ND texture is suppressed because finer MoC particles prevent the grain boundary migration. On the other hand, unfavorable texture {001}<110> significantly reduces with Mo increasing, which is attributed to that part of solution C in matrix has been fixed during recrystallization. In addition, the addition of Mo can enhance hardenability strongly and MoC easily re-dissolve at high temperature, which is favor to form martensite in dual-phase steel.     

铝和铬在无取向电工钢晶粒长大过程中对晶界的作用

研究了铝和铬元素在无取向电工钢晶粒长大过程中对织构及晶界变化的影响规律.试验结果表明:电工钢在晶粒长大过程中的主要织构组分均为{111}＜112＞.在晶粒生长期间,不加铝的1号试样中,{111}＜112＞、{111}＜110＞织构组分强化,而{100}＜001＞织构组分弱化;与1号试样相比,在加入0.2%的铝(质量分数...     

Texture in deep drawing columbium (Nb)-treated interstitial-free steels

The development of the crystallographic texture in hot-rolled, cold-rolled, and recrystallized Cb-treated interstitial-free steels was investigated using the crystallite orientation distribution analysis as well as X-ray pole figures. The influence of chemical composition of the steel and processing variables on texture and on normal and planar anisotropy of the γ-value of cold-rolled and annealed sheet are discussed and compared with those of aluminum-killed deep drawing steels. While, in terms of ideal orientation components, the re-crystallization texture of aluminum-killed steels can be described as having significant amounts of {lll}〈110〉 and {lll}〈112〉 components, Cb-treated steels show these components and in addition even stronger {554}〈225〉 and {322}〈296〉 components. Distinctions in the hot-rolled texture, the cold-rolled texture, and the recrystallization texture are described. Cb-treated steels have an entirely different planar distribution of γ values or plastic strain ratios compared with aluminum-killed steels. The resulting average γ value, γ_m, is significantly higher for Cb-treated steels and results in superior deep drawing characteristics. A. ELIAS is deceased.     

再结晶阶段加热速度对低碳冷轧板罩式退火过程组织和织构的影响

在实验室条件下模拟CSP热轧板为基板生产的低碳冷轧板罩式退火过程,研究再结晶阶段加热速度对冷轧板罩式退火过程组织和织构的影响。结果表明,压下率83.3%的冷轧板,随着再结晶阶段加热速度的增加,会使试样再结晶温度降低,再结晶过程提前完成,{001}110织构变强,{111}110织构先减少后增加,{111}112织构先减少后增加出现峰值,当加热速度超过50℃/h时又减小。在加热速度30~40℃/h间变形织构{112}110有较低的密度值。再结晶阶段加热速度40℃/h的退火工艺成品组织为饼形晶粒,{001}110织构密度较低,{111}110和{111}112密度较强,密度值接近。     

初次再结晶退火工艺对3%Si取向硅钢组织和织构的影响

试验研究了0.3 mm取向硅钢冷轧板(/%:0.046C,3.07Si,0.09Mn,0.029P,0.004S,0.005Al)的退火温度(760~880℃7 min)和退火时间(820℃3~9 min)对该钢的晶粒尺寸,再结晶和织构的影响。结果表明,最佳初次再结晶退火工艺为820℃5 min,该钢的平均晶粒尺寸为14.20μm,完全再结晶率为92%,不利{111}<110>结构含量为3.16%,有利织构{111}<112>,{012}<001>和高斯织构含量分别0.40%,4.73%和2.46%。     

Texture Development in the Ni47Ti44Nb9 Shape Memory Alloy During Successive Thermomechanical Processing and Its Effect on Shape Memory and Mechanical Properties

For improving the shape memory performance and mechanical properties of shape memory alloys (SMAs), crystallographic texture and second phase are generally induced in SMAs by suitable thermomechanical processing. For this purpose, the development of texture in the Ni₄₇Ti₄₄Nb₉ SMA during successive processing (e.g., hot forging, hot rolling, cold rolling, and heat treatment) and the effects of texture, grain size, and β-Nb particle precipitation on recoverable strains and tensile properties were studied. In the hot-forged and hot-rolled Ni₄₇Ti₄₄Nb₉ alloy rods, intense 〈111〉 fibers are formed, and water quenching from 873 K and 1123 K (600 °C and 850 °C) leads to the decrease in intensity of 〈111〉 fiber in the hot-rolled rod. When the hot-forged rod is hot-rolled into sheet, intense {001} and weak {123} fibers appear, but grain growth leads to the disappearance of {001} fiber and {110}〈001〉 becomes the strongest component. Cold-rolling deformation of the hot-rolled sheet promotes the development of γ-fiber and the convergence of {332} and {123} fibers to {233}〈110〉 and {123}〈121〉 components, respectively, and the intense component is turned into {111}〈110〉; in this case, the recoverable strain (ε _SRS) and tensile yield strength (σ _YS ) exhibit an anisotropy. When the quenching temperature is 1123 K (850 °C), some weaker components appear, the anisotropy of ε _SRS disappears, and the difference level in σ _YS along the rolling direction (RD) and transverse direction (TD) becomes smaller. Therefore, an appropriate heat-treatment temperature should be selected to maintain the deformation texture and also to obtain fine grains for different thermomechanical processing.     

Crystallite orientation distribution analysis of the cold rolled and recrystallization textures in low-carbon steels

The development of the cold rolled and recrystallization textures in low-carbon rimmed and killed steels was investigated using the crystallite orientation distribution analyses. With increasing cold reduction low-carbon steels exhibit the simultaneous development of a partial <110> fiber axis parallel to the rolling direction and a <111> fiber axis parallel to the normal direction. The strongest individual texture component rotates from a {111} <110> at 60 pct cold reduction towards a {112} <110> at 80 pct. During the early stages of recrystallization the (110) and <111> fiber textures decrease in both the rimmed and killed steels. However, the decrease in the <111> fiber texture is greater in the rimmed than in the killed steel. With further recrystallization and grain growth this <111> fiber texture increases in both steels but to a greater extent in the killed steel. The strongest individual texture component after complete recrystallization is the {111} <110>, being ∼5.5 and ∼3.0 times random in the killed and rimmed steel, respectively.     

Decomposition of Fe-Ni martensite: Implications for the low-temperature (≤500 °C) Fe-Ni phase diagram

The low-temperature (<500 °C) decomposition of Fe-Ni martensite was studied by aging martensitic Fe-Ni alloys at temperatures between 300 °C and 450 °C and by measuring the composition of the matrix and precipitate phases using the analytical electron microscope (AEM). For aging treatments between 300 °C and 450 °C, lath martensite in 15 and 25 wt pct Ni alloys decomposed with γ [face-centered cubic (fcc)] precipitates forming intergranularly, and plate martensite in 30 wt pct Ni alloys decomposed with γ (fcc) precipitates forming intragranularly. The habit plane for the intragranular precipitates is {111}_fcc parallel to one of the {110}_bcc planes in the martensite. The compositions of the γ intergranular and intragranular precipitates lie between 48 and 58 wt pct Ni and generally increase in Ni content with decreasing aging temperature. Diffusion gradients are observed in the matrix α [body-centered cubic (bcc)] with decreasing Ni contents close to the martensite grain boundaries and matrix/precipitate boundaries. The Ni composition of the matrix α phase in decomposed martensite is significantly higher than the equilibrium value of 4 to 5 wt pct Ni, suggesting that precipitate growth in Fe-Ni martensite is partially interface reaction controlled at low temperatures (<500 °C). The results of the experimental studies modify the γ/α + γ phase boundary in the present low-temperature Fe-Ni phase diagram and establish the eutectoid reaction in the temperature range between 400 °C and 450 °C. Formerly Research Assistant, Department of Materials Science and Engineering, Lehigh University     

Development of {111} transformation texture in interstitial-free steels

The evolution of the transformation texture in two Ti₄C₂S₂-stabilized interstitial-free (IF) steels (Ti-and Ti/Nb-) was studied as a function of different thermomechanical processing (TMP) parameters using orientation distribution function (ODF) analysis. The ensuing transformation texture, largely independent of the steel composition and TMP path of the kind used in these experiments, is strongly related to the combination of initial austenite grain size and the amount of deformation applied in the early rolling passes. It is proposed that the formation of crystallographic heterogeneities in austenite induces the gamma-fiber texture development around the {111} components in the ferrite.     

Microstructure and texture of hot-rolled Cb-Ti and V-Cb microalloyed steels with differences in formability and toughness

The relationship between microstructure and formability (also toughness) of industrially processed Cb-Ti and V-Cb steels with similar yield strength of about 600 MPa and total elongation of 20 pct was examined. The steels were processed under similar conditions and any variations in processing history were unintentional. Cb-Ti steels exhibited superior formability and toughness in relation to V-Cb steels. The improved formability and toughness of Cb-Ti steels is attributed to the cumulative contribution of relatively finer grain size, narrow ferrite grain size distribution, inherently more ductile behavior and microplasticity, the reduced intensity of {100}〈011〉 texture, and slightly higher intensity of the desired {332}〈113〉 texture.     

Fiber texture and substructural features in the caliber-rolled low-carbon steels

Caliber rolling at the recrystallization temperatures of ferrite is a new process that was developed to fabricate an ultrafine-grained microstructure for low-carbon steels. In the present investigation, the electron backscattered diffraction (EBSD) measurement was carried out to characterize thoroughly the texture and substructural features in two caliber-rolled low-carbon steels, with special attention on the effects of a phosphorus addition to the steel and the annealing treatment after rolling. Finer ferrite grains appeared in the phosphorus-added steel under the same rolling condition. The phosphorus addition caused also the stronger <110>//rolling direction (RD) fiber texture in the caliber-rolled steel bars and, hence, showed a larger average Taylor factor than the steel without phosphorus. Microband features within the ultrafine ferrite grains were characterized with both transmission electron microscopy (TEM) observation and orientation-imaging micrograph (OIM) analysis. Nearly half of the low-angle boundaries, whose kernel average misorientation was larger than 0.8 deg, were found to have the planar character and were specifically parallel to the {110} or {112} planes. In the as-rolled condition, the total volume fraction of the low-angle boundaries was 0.3 and 0.23 in the steels with and without a phosphorus addition, respectively. More {112}-type planar boundaries were observed than the {110} type boundaries in both steels. Annealing treatment increased the volume fraction and changed the type of the low-angle boundaries in both steels. Using the model proposed by Peeters et al., the critical resolved shear stress (CRSS) of the 110 and 112 slip systems was calculated by considering the contributions of both the randomly distributed dislocations and the oriented planar boundaries. We concluded that the contribution of the planar low-angle boundaries to the total CRSS was less than 2 pct. The texture features and dislocation structure in the ultrafine-grained steels influenced the mechanical behavior to some extent, in addition to the refined ferrite grains. Phosphorus added to the steels showed a larger influence on the formation of texture and the retained dislocation structure, than that on the grain refinement in the caliber-rolling process.     

Influence of initial ingot breakdown on the microstructural and textural development of high-purity tantalum

The influence of initial ingot breakdown on the rolling and recrystallization textures of high-purity tantalum plate was investigated using optical microscopy and X-ray diffraction. The four ingot breakdown processes investigated include two commercial processes and two processes new to tantalum. Correlations among the four ingot breakdown processes, the recrystallized grain size, and the final texture were established. Of the four breakdown processes investigated, the plate from the completely upset-forged ingot had the strongest {111}<110> and {111}<112> texture components, while the plate from the side-forged ingot recrystallized with a mixed texture. Increased upset forging along the ingot centerline strenghened the {111}<uvw> orientations and weakened the {100}<uvw> orientations in the annealed plates. Recrystallization studies were conducted on the rolled plates to develop an optimum texture with both {111}<110> and {111}<112> texture components in the final recrystallized plate.