The hot‐rolled sheets of low‐grade electrical steels undergo complete austenite‐ferrite phase transformation, resulting in fine equiaxed grains in the sheets. These fine initial grains eventually lead to a strong detrimental {111} texture in the final product after cold‐rolling and annealing process. This work, based on the phase transformation delay of columnar grain structure in cast slabs, proposes a novel approach called metastable ferrite hot rolling, namely, a two‐stage heating at 900 °C and then at 1100 °C shortly and hot rolling, to avoid complete transformation and to retain original {100} oriented regions. In addition, low‐temperature annealing is employed to increase grain sizes of hot‐rolled sheets thereby improving the final texture and magnetic properties after cold‐rolling and annealing. The results indicate that metastable ferritic columnar grains can be maintained during the two‐stage heating process at 1100 °C and primarily undergoes subgrain growth. The transformation from ferrite to austenite at 1100 °C is very slow. During the hot rolling with a high 86% reduction by two passes, the notable grain refinement is mainly caused by dynamic recrystallization rather than dynamic phase transformation as evidenced by the observation from the rolling plane.

Transformation texture is normally different to deformation and recrystallization textures, thus influencing materials properties differently. As deformation and recrystallization are often inseparable to transformation in materials which shows a variety in types such as diffusional or non-diffusional transformations, different phenomena or rules of strengthening transformation textures occur. This paper summarizes the complicated phenomena and rules by comparison of a lot of authors’ published and unpublished data collected from mainly electrical steels, high manganese steels and pure titanium sheets. Three kinds of influencing deformation are identified, namely the dynamic transformation with concurrent deformation and transformation, the transformation preceded by deformation and recrystallization and the surface effect induced transformation, and the textures related with them develop in different mechanisms. It is stressed that surface effect induced transformation is particularly effective to enhance transformation texture. It is also shown that the materials properties are also improved by controlled transformation textures, in particular in electrical steels. It is hoped that these phenomena and processing techniques are beneficial to the establishment of transformation texture theory and property improvement in practice.

The effects of various initial structures and heating and cooling rates on the columnar‐grained transformation temperature are studied by a thermal dilatometer and electron backscatter diffraction. The results show that deformation can reduce the thermal hysteresis more effectively than decrease the heating rate, and the phase transformation hysteresis of the deformed sample is the smallest during heating, followed by the columnar‐grained sample with a slow heating rate, whereas the columnar‐grained sample with a fast heating rate has the largest phase transformation hysteresis. Moreover, the dilatational amount changes greatly with cooling rate. The coarse columnar grains can severely restrain dilatation. The smaller dilatational amount is related to the incomplete phase transformation of the columnar grains and also related to the suppression of the dilatational amount of the small grains by the surrounding columnar grains. In contrast, the largest dilatational amount is caused by the relatively sufficient phase transformation. In addition, the changes of the transformation temperature and the dilatational amount are mainly induced by the grain size effect and the inhomogeneity of the structures, but {100} texture can affect the uniformity of grain size.

Solidification behaviors of Pt-containing 718Plus superalloyswere studied by scanning electron microscopy (SEM), energy dispersive spectrum (EDS), differential scanning calorimetry (DSC) and simulation calculations. It is found that Pt increases solidification range and decreases solidus temperature of the alloy and precipitation temperature of Laves + γ eutectic phase since Pt enlarges the region of γ phase by increasing Nb solubility. In addition, Pt segregates to the interdendritic region and increases the segregation of Nb and Tiin the interdendriticregion due to the strong attractive interactions between Pt and Nb/Ti. As a result, Pt promotes the precipitation of the Laves + γ eutectic phase and η phase around eutectic phase. The increase of solidification range and segregation degrees of Nb and Al caused by Pt also promotes the precipitation and growth of γ’ + γ” phase around eutectic phase. These results provide experimental bases for understanding the mechanism of Pt in solidification behavior of superalloys.

The pseudobinary phase diagrams of Pt‐containing and Pt‐free 718Plus alloys are constructed to better understand how Pt affects the eutectic reaction. The phase transition temperature is obtained by differential scanning calorimetry (DSC). The compositions of γ phase, eutectic phase, and Laves phase are obtained by energy dispersive spectrometry (EDS). Nb is set as the independent variable in the phase diagram as Nb is the most susceptible to concentration of eutectic phase during solidification. The reliability of the pseudobinary phase diagrams is verified by the results reported. According to the diagrams, on one hand, Pt increases the concentration of Nb required for the (Laves + γ) eutectic reaction by increasing lattice space. On the other hand, the increased concentration of Nb and the slow diffusion rates of Pt and Nb cause the decrease in the temperature of the eutectic reaction. As a result, the eutectic point in the pseudobinary phase diagram moves down and shift to the right. Herein, experimental data are provided for enriching the phase diagram of 718Plus alloy.

Enrichment ratio was treated as a constant in interface segregation kinetic equation while it was confirmed to be a variable experimentally and theoretically. This leads to a large deviation of the calculated concentration from the measured one. In this study, a kinetic model revealing the intrinsic variation of enrichment ratio is examined by the experimental results of grain-boundary segregation of P in Cr-Mo steel and Fe-P-B alloy. The results are compared to the concentrations calculated by the beginning and equilibrium enrichment ratios respectively. Excellent agreements between the experimental and the calculated curves confirm the quantified variation range of enrichment ratio to be reliable and rational.

The relationship between the critical time and evaporation parameter is discussed in terms of the kinetic model for surface segregation in the case of evaporation. An interesting phenomenon is observed that the variation of critical time obeys a C‐type law in kinetic curves with different evaporation parameters. The C‐type law of critical time is found to be caused by that of maximum evaporation flux. The existence of C‐type law is proved by the fitted kinetics curve of the Mg surface segregation of Al–0.8 wt% Mg alloy, which confirms the model of surface segregation in the case of evaporation to be reliable.

A kinetic model is proposed to characterize surface segregation in the case of evaporation. The kinetics is formulated using the difference between the diffusion rate of solute atom in the bulk and the evaporation rate of solute atom from the surface layer. The first-order reaction equation is applied to quantify evaporation flux. A balanced state is quantified when the vapor and ambient pressure is equal and thus a complete quantification of the kinetics forms. The kinetic curve is convex prior to critical time and concave after. The maximum surface concentration decreases as evaporation parameter decreases. The kinetics of Mg surface segregation of Al-0.8 wt% Mg alloy is fitted. An enrichment ratio of 16.484 and evaporation parameter of 0.57 are the values that fit the experimental results the best. The balanced surface concentration of Mg is calculated and implies further evaporation with prolonged time. The proposed model can adequately describe surface segregation in the case of evaporation, and the formulated kinetics can satisfactorily quantify this phenomenon. (C) 2019 Elsevier B.V. All rights reserved.

<span id="ChDivSummary" name="ChDivSummary" class="abstract-text">对高锰相变诱发塑性（TRIP）钢冷轧过程的组织转变特征以及奥氏体（g）和bcc结构马氏体（a’-M）的织构演变规律进行了研究,对形变诱发a’-M在高温时的逆转变行为进行了分析。结果表明,中等变形量下g已经大部分转变为a’-M,此时残余的g和hcp结构马氏体（e-M）接近机械稳定化。变形量进一步增加时,主要发生a’-M的形变并形成平行于轧向（RD）的长条状组织。中等变形量下,a’-M主要具有{113}&lt;110&gt;、{554}&lt;225&gt;和旋转立方（{001}&lt;110&gt;）等典型的相变织构。随变形量增加,a’-M的{113}&lt;110&gt;取向明显转向稳定取向{223}&lt;110&gt;,形成典型的冷轧织构（&lt;110&gt;∥RD）。在650～850℃退火时发生了a’-M的逆转变（a’-M→g）及g的再结晶。a’-M的逆转变以扩散方式进行,存在Mn、Al元素在g和a’-M中的再分配。a’-M的逆转变是通过g直接吞并临近的形变a’-M完成的,形成的g晶粒为长条状且存在较多的亚晶。逆转变形成的g与形变g的织构类型相同,这种织构遗传是由于残余g直接长大产生的。随退火时间延长,长条状g晶粒又通过亚晶合并的方式发生再结晶而被等轴g晶粒取代。</span>

To find out the reason of poor secondary reaystallization behavior in thin-gauged grain-oriented steel, EBSD technique is applied to reveal the grain growth behavior of thin-gauged steel processed by HiB steel method under high cold-rolling reduction. Nitriding treatment with different times is conducted to ensure the occurrence of secondary recrystallization in thin-gauged grain-oriented steel and to determine The effect of nitrogen content. Attention is put on the influence of {114}< 418 > texture on the abnormal growth of Brass and Goss grains. Results show that, at initial stage of secondary recrystallization, {114}< 418 > grains in the surface region of sheets possess obvious growth advantage than the other oriented grains. If these grains in the surface region grew to the central layer of sheet and swallowed the nucleus of secondary recrystallization, abnormal growth could not occur. In contrast, reinforcing the inhibitors at surface region of sheet by nitriding treatment will avoid the excessive growth of surface grains and therefore improve magnetic properties of steel significantly. The {114}< 418 > grains are. adverse to the abnormal growth of Brass-oriented and scattered Goss grains in way of island grains, but their effeet on the abnormal growth of Goss grains is weaker.

本文以热轧常化板为初始材料,采用二次冷轧法与三次冷轧法制备了0.1 mm厚的取向硅钢薄带,测定相应的磁性能,并通过EBSD取向成像技术检测了二次冷轧法与三次冷轧法各工艺过程中织构与组织演变规律.结果表明,采用最终冷轧压下率适中的三次冷轧法,能在冷轧至0.1 mm时保存较多的高斯晶核,使得高温退火后的磁性能明显优于二次冷轧法.最终冷轧压下率通过影响脱碳退火后样品中的{111} 〈112〉织构组分及Goss晶粒数量对最终二次再结晶产生重要影响.

Strain-induced martensites in high manganese TRIP/TWIP steels were investigated in the presence of thermal martensites and under the influence of austenitic grain orientation by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). Before deformation, the morphology of alpha'-M depended mainly on the number of variants and growing period. Regardless of martensite morphologies and deformation, the Kurdjumov-Sachs (K-S) orientation relationships always maintained. The 6 alpha'-M variants formed from a plate of epsilon-M were of 3 pairs of twins with a common axis < 110 >(alpha') parallel to the normal of {111}(gamma) habit plane to minimize transformation strain. When alpha'-M could be formed only by deformation, it nucleated at the intersection of e-M variants and grew mainly in thick epsilon-M plates. Thick epsilon plates promoted significantly the alpha'-M and weakened the influence of grain orientations. During tension, the transformation in < 100 >-oriented grains was observed to be slower than that in < 111 >-oriented grains. Deformation twins promoted epsilon-M formation slightly and had no apparent effect on alpha'-M. Deformation increased the number of epsilon-M variants, but reduced that of alpha'-M variants.

The behaviors of different inhibitors including their composition, size, distribution, coalescence and coarsening were experimentally studied. It was observed that during secondary recrystallization of the tested steel, the key inhibition effect was produced by Cu 2 S and AlN, but not MnS. With the increase of temperature, the size distributions of AlN and Cu 2 S were changed to some extent. However, significant changes in particle size were not observed. The initial temperature of abnormal growth was determined by measuring the evolution of particle sizes and their distribution density during heat treatment. AlN and Cu 2 S are the dominant inhibitors and both are necessary, which is verified by calculating the Zener factor.

Static and dynamic recrystallization and grain orientations in a hot-compressed Fe-3 wt% Si electrical steels were studied at different temperatures using Gleeble simulator and EBSD technique, particularly focusing on the effect of small amount of austenite on ferritic microstructure and orientations. The results show that microstructure of the compressed steel, depending on deformation temperature, consisted of elongated and deformed ferrite, pearlite and fine equal-axed ferrite. The elongated ferrite experienced dynamic recovery or continuously dynamic recrystallization, and the ferrite around austenite underwent accelerated dynamic recrystallization even in a discontinuous style. Static recrystallization was observed in both ferrite and austenite, and was most prominent in austenite at 1050°C, whereas it became more significant in ferrite with increasing deformation temperature. Grain orientations are mainly <111> and <100> in samples compressed at various temperatures. Most orientations of fine equal-axed ferrite are similar to those of elongated ferrite, however orientation of <110> is also observed.

Experiments were performed by interrupting secondary recrystallization processes in a CGO silicon steel. The results show that the average size of Goss grains is obviously larger than that of other grains just before abnormal growth in the temperature-rising process of secondary recrystallization. The amount of different orientation grains at this stage is almost the same as that in a decarburizing-annealed sample. Goss grains can first grow abnormally due to preferred coarsening of such inhibitors as MnS in Goss grains. It is noted that only Goss grains with seriously curved grain boundaries or several grains merged by slight growth can be the nuclei of secondary grains. During abnormal growth of Goss grains, their grain boundaries have zigzag shapes. It is believed that this unique growth pattern is the reason that secondary recrystallization can finish quickly.

Objective Sharp Goss texture is a prerequisite for excellent magnitic property of grain oriented silicon steel.Much attention is paid to its formation,which is not fully understood yet.In this paper EBSD technique is used to analyze the characteristics of the distribution of Goss-oriented grains in hot rolled and primarily recrystallized sheets.Our primary results show that Goss-oriented grains in sub-surface layer firstly formed as deformed grains and later may recrystallize and develop to equal axial grains.The primarily recrystallized sample with less Goss grains and a higher percentage of {111}<11 2> grains evolved into sharp Goss texture after secondary recrystallization.The texture component of {111}<1 10> was observed to be detrimental by decreasing the intensity of Goss texture.

Yttrium-doped strontium titanate with B-site deficiency (Y0.08Sr0.92Ti1−xO3−δ) is synthesized via conventional solid-state reaction. The effect of B-site deficiency on the lattice parameter, sinterability, microstructure and electrical properties of Y0.08Sr0.92TiO3−δ is investigated. The charge compensation mechanism for B-site deficiency is proposed. The limit of B-site deficiency in Y0.08Sr0.92Ti1−xO3−δ is below 5mol % in Ar with 5% H2 at 1500°C. The sinterability of Y0.08Sr0.92Ti1−xO3−δ decreases slightly with increasing deficiency level (x). Compared with Y0.08Sr0.92TiO3−δ, the electrical conductivity of Y0.08Sr0.92Ti1−xO3−δ samples decreases while the ionic conductivity increases with increasing B-site deficient amount. It is assumed that the deficiency of Ti in Y0.08Sr0.92Ti1−xO3−δ is charge compensated by the increase of oxygen vacancy concentration and the decrease of Ti3+ concentration. Y0.08Sr0.92Ti1−xO3−δ shows a relatively stable electrical conductivity at different oxygen partial pressures and displays an excellent chemical compatibility with YSZ electrolyte below 1200°C.

Self-lubrication alloys containing sulphide with different contents of manganese were prepared by a induction melting and casting process.The formation of sulfide in these alloys and their fracture were researched both with a scanning electron microscope and microstructure analysis.The results show that the fracture surface is in form of brittle cleavage fracture when sulfides locate in pearlite with a low toughness,and the fracture surface is in form of ductile dimple fracture when sulfides locate in ferrite with a high toughness.The sulfides mainly include FeS and present as a composite phase containing some small hard particles of V,Nb,Ti sulfides for the alloy with a lower content of manganese,whereas the sulfides mainly comprise MnS for the alloy with a high content of manganese.

Micro-scaled Sn–Sb–Ni alloy composite was synthesized from oxides of Sn, Sb and Ni via carbothermal reduction. The phase composition and electrochemical properties of the Sn–Sb–Ni alloy composite anode material were studied. The prepared alloy composite electrode exhibits a high specific capacity and a good cycling stability. The lithiation capacity was 530mAhg−1 in the first cycle and maintained at 370–380mAhg−1 in the following cycles. The good electrochemical performance may be attributed to its relatively large particle size and multi-phase characteristics. The former reason leads to the lower surface impurity and thus the lower initial capacity loss, while the latter results in a stepwise lithiation/delithiation behavior and a smooth volume change of electrode in cycles. The Sn–Sb–Ni alloy composite material shows a good candidate anode material for the rechargeable lithium ion batteries.

SHS-gravitational process was developed to synthesize the ceramic lined steel pipe, especially for elbow, conical pipe, three-way and four-way pipe and pipe with a small diameter. In SHS-gravitational process, the molten ceramic, which separated out from the reaction products due to their density difference, solidified to form the ceramic lined layer in the steel pipe when contacted with the steel pipe wall. With an X-ray diffractometer and a scanning electron microscope, it can be found that the ceramic layer is composed of α-Al2O3 and FeAl2O4. A small amount of iron also remains in the ceramic layer. There is a thin equiaxed grain area of alumina near the steel pipe wall, and then alumina was grown in form of dentrite to the surface of ceramic layer. FeAl2O4 distributes among alumina dentrite. Although the ceramic layer was solidified from one end to another end of a pipe, the microstructure of ceramic layer was almost uniform throughout the whole length of the pipe.