Texture evolution by grain growth in the presence of MnS and AIN precipitates in Fe-3% Si alloy

Texture evolution by grain growth in the presence of MnS and AIN precipitates in Fe-3% Si alloy was investigated by X-ray diffraction and electron channelling technique. Two texture groups A and B evolved from the primary texture (grain diameter of 6 μm) composed mainly of {111} 〈112〉 oriented grains. The group A (grain diameter of 2600 μm) were mainly composed of two subgroups, one with Goss oriented grains and another with Goss oriented grains rotated around ND axis by about 15 and 20°, while the group B (grain diameter of 700 μm) had an intensity level of about one seventh of that of the group A and had orientations centering around {112} 〈110〉. The ideal Goss or near Goss oriented grains of group A were infrequent in the primary recrystallized structure and made few Σ1 boundaries. They made large numbers of Σ9 boundaries though, or had a large value of the product (number of grains at orientation × number of σ9 boundaries made by them). The grains in orientations within the texture group B were fairly frequent in the primary structure and made large numbers of Σ1 boundaries. The value of the product (number of grains at orientation × number of Σ9 boundaries made by them) was large. The mechanism of the evolution of the A and B groups is considered to be due to (1), the higher mobility, in the presence of precipitate inhibitors, of adjacent grains in Σ9 coincidence or in coincidence orientations with a 〈110〉 rotation axis; (2), because Σ1 related grains are stable and less mobile under these conditions.     

热处理对高强大梁钢冲击吸收功的影响分析

为了研究热处理工艺对高强大梁钢冲击性能的影响,采用扫描电镜、透射电镜和EBSD等方法对700L不同热处理工艺后的冲击性能进行了研究。结果显示,热处理工艺对700L的冲击性能影响显著。在低于400 ℃退火时,冲击性能较原板有所提高;在高于550 ℃退火时,钢板组织发生变化,晶界析出大量渗碳体,冲击性能明显恶化。原板经不同奥氏体化温度空冷处理后,850 ℃空冷后的钢板拥有最佳的冲击性能,其组织由等轴的细小铁素体与M/A岛组成。织构分析结果表明,原板拥有较强的{001}〈110〉型织构,这类型织构可能对钢板冲击性能有不利影响,经低温退火处理后,{001}〈110〉型织构强度减弱,经奥氏体化处理后织构消失。     

二次冷轧压下率对镀锡板组织和性能的影响

 为了开发二次冷轧镀锡板,采用硬度计、拉伸试验机、光学显微镜、透射电镜和X射线衍射仪研究了二次冷轧压下率对镀锡板组织和性能的影响规律。结果表明,随着二次冷轧压下率提高,试验钢的硬度和强度提高,各向异性增加,伸长率降低,当二次冷轧压下率为20%时可获得较高的硬度和伸长率的匹配。同时二次冷轧压下率对织构影响明显,当压下率为20%～40%时,α取向线中最高取向密度出现在{223}〈110〉～{445}〈110〉之间,可达到6.2,并且随变形量增加,γ取向线中{111}〈110〉取向密度逐渐从3.1降低到2.7,{111}〈112〉取向密度逐渐从4.9提高到5.3。     

Structural Engineering with NiTi. II: Mechanical Behavior and Scaling

This paper continues to address the overarching goal to provide a more unified understanding of NiTi shape memory alloys intended for use in structural applications by attempting to link standard processing practice and basic materials characterization to the deformation behavior of large diameter bars. Results from cyclic tensile tests performed on large diameter Ni-rich polycrystalline NiTi bars are presented. Coupon specimens taken from deformation processed bars with diameters of 12.7, 19.1, and 31.8?mm are tested along with their respective full-scale specimens. The coupon tests results reveal small and highly variable differences between specimens taken from the different size bars. The full-scale specimen tests continue to show the presence of the R phase, but lack a Lüders-like transformation. A comparison of the results suggests that coupon specimens provide only limited information in terms of the full-scale behavior. Full-scale tests using an earthquake-type loading then show similar behavior to the tensile cyclic tests suggesting the ability to use NiTi in structural applications. Overall, this paper and Tyber et al. 2007 provide a multiscale analysis of NiTi shape memory alloys to be used by both material scientist and civil engineers in the development of applications for NiTi.     

快速加热条件下BH钢再结晶规律

 通过Gleeble-3500热模拟试验机以及运用金相、显微硬度、EBSD技术等研究方法,研究了不同加热速率对BH钢再结晶退火组织和织构演变的影响。结果表明：再结晶温度随加热速率的提高而升高。加热速率的提高,缩短了BH钢完成再结晶所需时间。快速加热条件下,BH钢再结晶晶粒得到细化,再结晶织构组分强度降低。EBSD分析发现：提高加热速率,再结晶完成后,再结晶织构仍以有利于深冲性能的管状γ织构为主。再结晶结束后,升高温度和增加保温时间有助于{111}织构的发展。在780℃保温一定时间的条件下,低加热速率形成以{111}〈112〉组分为主的再结晶织构,而快加热速率下{111}〈110〉织构组分得到一定的发展,γ织构强度分布更加均匀,有利于BH钢的成型性能。     

低温加热取向硅钢组织与织构演变研究

采用OM、EBSD、XRD分析研究了含Cu低温加热取向硅钢组织、织构的演变特征,研究结果表明：热轧板中存在铁素体层和珠光体层彼此交替的带状组织,且显微组织在厚度方向上分布不均匀,热轧板中{001}〈110〉、{112}〈110〉织构以及{110}〈001〉织构在板厚方向上分布不均匀;经过冷轧后,铁素体晶粒被严重拉长,形成了沿轧向伸长的纤维状组织,冷轧板织构类型主要是α织构和γ织构;脱碳时基体发生回复再结晶,显微组织为单一的铁素体等轴晶粒,织构主要为γ织构;二次冷轧板经渗氮后织构仅从强度上有所降低,其织构类型变化不明显。成品二次再结晶组织发展比较完善,晶粒尺寸约为10~20 mm。织构类型为锋锐的Goss织构。成品磁感B800达到了1.926 T,铁损P1.7/50为1.047 W/kg。     

Crystallographic Reconstruction Study of the Effects of Finish Rolling Temperature on the Variant Selection During Bainite Transformation in C-Mn High-Strength Steels

The effect of finish rolling temperature on the austenite-(γ) to-bainite (α) phase transformation is quantitatively investigated in high-strength C-Mn steels using an alternative crystallographic γ reconstruction procedure, which can be directly applied to experimental electron backscatter diffraction mappings. In particular, the current study aims to clarify the respective contributions of the γ conditioning during the hot rolling and the variant selection during the phase transformation to the inherited texture. The results confirm that the sample finish rolled at the lowest temperature [1102 K (829 °C)] exhibits the sharpest transformation texture. It is shown that this sharp texture is exclusively due to a strong variant selection from parent brass {110} \( \left\langle {1\bar{1}2} \right\rangle \) , S {213} \( \left\langle {\bar{3}\bar{6}4} \right\rangle \) and Goss {110}〈001〉 grains, whereas the variant selection from the copper {112} \( \left\langle {\bar{1}\bar{1}1} \right\rangle \) grains is insensitive to the finish rolling temperature. In addition, a statistical variant selection analysis proves that the habit planes of the selected variants do not systematically correspond to the predicted active γ slip planes using the Taylor model. In contrast, a correlation between the Bain group to which the selected variants belong and the finish rolling temperature is clearly revealed, regardless of the parent orientation. These results are discussed in terms of polygranular accommodation mechanisms, especially in view of the observed development in the hot-rolled samples of high-angle grain boundaries with misorientation axes between 〈111〉γ and 〈110〉γ.     

不同上冷床温度对螺纹钢组织性能的影响

 为了研究不同上冷床温度对螺纹钢组织演化规律及性能的影响,利用拉伸试验机和扫描电子显微镜对不同上冷床温度的螺纹钢进行了力学性能检测和金相组织分析,并通过相变理论解释了发生相变的原因,探讨了上冷床温度对螺纹钢性能的影响。结果表明,为了发生相变,其体系化学驱动力减少必须克服体系弹性能的增加和形成新相引起表面能的增加。同时形变会使形变储存能ΔG_D增加。从而使相变驱动力增加,进而导致相变温度上升。随着螺纹钢上冷床温度的降低(不应低于临界相变温度),表面和中心均形成铁素体和珠光体,屈服强度由435升高到440 MPa,表面维氏硬度由207上升到257,这是因为随着上冷床温度降低,其表面形成越来越多的回火索氏体,抗拉强度有升有降无明显规律,而其晶粒度由10.5上升到13.5。     

Fe-6.5%Si合金温轧后退火过程中再结晶行为

用电子背散射技术观察了700℃温轧板在退火过程中的组织及织构演变以了解其再结晶行为.结果表明,温轧织构由强的（111）〈112〉、较弱的〈110〉∥RD及Goss组成,再结晶织构与之相似.〈110〉∥RD及（111）〈112〉新晶粒首先形成于与之构成小角度晶界的形变晶粒的晶界附近,而在角隅及组织不均匀区等位置孕育出与周围晶粒构成大角度晶界的晶核,择优取向不明显.退火过程中（111）〈112〉在形变组织中累积,最终转化为（111）〈112〉再结晶晶粒.分析认为,温轧后退火是不均匀组织在低储存能驱动下的再结晶过程.（112）〈110〉及（111）〈112〉形变拉长晶粒多发生连续再结晶从而退火织构与形变态相似.在角隅区形成核心进而发生不连续再结晶,核心取向的统计性及不连续晶核的长大弱化再结晶织构,其中Goss晶粒多以此方式形成于（111）〈112〉晶粒内部.      

稀土Y对6.5%Si高硅钢热轧和温轧组织织构演变的影响

摘要：以无稀土与含质量分数为0.03%的Y的6.5%（质量分数）Si高硅钢为研究对象,经过热轧、常化、温轧及退火工艺制备出0.5mm高硅钢薄板,采用EBSD、SEM和EDS测试技术,研究了稀土Y对高硅钢热、温轧组织织构演变的影响。结果表明,热轧板中以{001}〈110〉和{110}〈001〉织构为主,常化板织构类型遗传了热轧板,添加稀土Y削弱了热轧、常化板中整体织构强度。含Y高硅钢较无稀土高硅钢温轧剪切带增多,位错密度增加,α织构减弱且γ织构增强。随着退火温度升高,温轧板以{001}〈140〉为主的λ织构和{114}〈481〉为主的α*织构强度不断增强。添加稀土Y削弱了相同退火温度下温轧板的λ织构与α*织构的强度,然而η织构却有所增强,这与稀土Y促进剪切带形核有关。添加质量分数为0.03%的Y具有细化晶粒的作用,细小弥散的稀土Y氧化物阻碍晶界迁移是导致高硅钢温轧板再结晶晶粒细化的重要原因。     

X-ray diffraction study of the structural evolution in a grade 1469 (Al-Cu-Li) alloy during the production of hot-rolled sheets

X-ray diffraction is used to study the structural changes in a grade 1469 (Al-Cu-Li) alloy with a high lithium content that occur during the production of hot-rolled sheets according to the ingot → pressed strip → hot-rolled sheet schedule. In the pressed strip, a multicomponent Bs {110}〈112〉, Cu {211}〈111〉, and S {123}〈111〉 texture forms, which is typical of articles pressed from such alloys, and an unusual intense single-component texture of the Ex₁ {011}〈111〉 type forms in the hot-rolled sheets. Its formation is stimulated by cross rolling of the sheets. The low strength characteristics of the hot-rolled sheets after heat treatment are related to an elevated heating temperature used for quenching and to the oriented precipitation of the lamellar particles of the hardening T ₁ phase.     

JSP-双机可逆冷轧条件下IF钢织构研究

针对济钢现场工艺条件下生产的Ti-IF钢,利用X’Pert ProxX射线衍射宏观织构分析方法,研究了中薄板坯热连轧轧制及随后的冷轧、退火工艺过程中织构的变化规律。IF钢冷硬板主要织构类型为{111}〈110〉、{111}〈112〉和{001}〈110〉,其中{111}〈110〉织构强度达到12;再结晶退火后的IF钢退火板,主要织构类型为{111}〈110〉和{111}〈112〉,{111}〈110〉织构强度提高到15.37。济钢生产的Ti-IF钢获得了对板材成形最有利的{111}//ND织构。     

Dispersion strengthening in a hypereutectic Al-Si alloy prepared by extrusion of rapidly solidified powder

When a hypereutectic aluminum-silicon alloy containing 16 wt pct silicon was rapidly solidified into powder using the spinning water atomization process, the individual powder grains were predominantly aluminum that was supersaturated with silicon and also contained well-dispersed 0.02-μm silicon particles. Although the silicon particles grew when the powder was extruded into a bar at temperatures from 673 to 803 K at an extrusion ratio of 4.3 and an extrusion speed of 0.9 mm/s, the average diameter was maintained on a submicron level. When the extrusion temperature was decreased from 803 to 673 K, the average diameter of the silicon particles in the extruded bar decreased from 0.8 to 0.5 μm, while the Vickers hardness (HV) and the ultimate tensile strength of the extruded bar increased from 120 to 160 (HV) and from 330 to 500 MPa, respectively. Both the hardness and the tensile strength of the extruded bars were several times higher than those of conventionally cast bars of the same alloy with cooling rates from 10⁻¹ to 10² K/s. On the other hand, the elongation decreased from 5.5 to 3.1 pct when the extrusion temperature was decreased from 803 to 673 K.     

Structure, mechanical properties, and hydrogen permeability of Pd-Cu and Pd-Ru membrane foils prepared by magnetron sputtering

Magnetron sputtering is used to prepare thin (down to 7 μm) Pd-Cu and Pd-Ru membrane foils deposited on the surface of a SiO₂/Si heterostructure at 300 and 700 K. Condensed foils (CFs) of an ordered Pd-Cu solid solution (β phase with a CsCl-type structure) and a Pd-Ru solid solution (fcc lattice) are synthesized for the first time. The foils of both alloys are characterized by a gradient granular structure due to selective development of 〈110〉 and 〈112〉 textures and a 〈111〉 texture in the Pd-Cu and Pd-Ru foils during their deposition, respectively. The hardness of the free surface of both foils removed from the substrate is determined by nanoindentation. The hardness is 3.0–3.6 GPa and is 20–50% lower than that of the contact surface (at the interface with the substrate) owing to the gradient structure. The hydrogen permeability of the Pd-Cu CF (β phase) is higher than that of the Pd CF by almost an order of magnitude (effect of a less dense crystal lattice) and is 5–7 times higher than those of the Pd-Ru CF and the Pd-Cu foil prepared by rolling.     

Formation of Cube and Goss Texture After Primary Recrystallization in Electrical Steels

Recrystallization texture evolution in 2.1 pct Si electrical steel sheets was investigated with X-ray diffraction and electron backscattered diffraction (EBSD) analysis. The beneficial Cube ({100} 〈001〉 ) and Goss ({110} 〈001〉 ) components dominate primary recrystallization texture after final annealing at 1123 K (850 °C). It is found that Cube grains nucleate within {114} 〈481〉  deformed grains, and the nucleation of Cube grains is later than that of Goss grains during recrystallization. The formation of strong Cube and Goss texture is explained in terms of both the oriented nucleation and selective growth mechanisms.     

薄带连铸取向Fe-6.5％Si钢形变热处理过程组织演化

设计并利用双辊薄带连铸工艺制备出取向Fe- 6. 5%Si钢铸带,研究了热处理工艺对铸态、形变和初次再结晶组织、织构及析出物的影响规律。结果表明,铸带退火可以促进铸态组织中的柱状晶长大,同时增加200nm以下MnS- AlN或MnS- NbN复合析出物的面密度。随着铸带退火温度升高,冷轧组织中变形带宽度以及带内剪切带长度增加,初次再结晶织构中{111}〈112〉组分增强,{110}〈001〉晶粒所占比例增大。铸带退火有助于改善冷轧板高温退火过程中的二次再结晶行为,提升产品磁性能。     

Texture Produced by Abnormal Grain Growth in Friction Stir-Welded Aluminum Alloy 1050

The texture produced by abnormal grain growth in friction stir-welded (FSWed) aluminum alloy 1050 was shown to be dominated by the Brass {110}〈112〉, R {124}〈211〉 and S {123}〈634〉 orientations. These orientations were present in the simple shear texture developed during friction stir welding (FSW) and their preferential growth was hypothesized to be induced by relatively low stored energy.     

Stress asymmetry of stoichiometric NiAl single crystals

The yield stress properties of stoichiometric NiAl single crystals were investigated in terms of crystal orientation, temperature and the deformation mode. The calculated critical resolved shear stress (CRSS) was a strong function of crystal orientation, temperature and the deformation mode whether tension or compression. The CRSS was, in a wide range of experimental conditions, higher in the sequence of {110}〈100〉, {100}〈100〉 and {hk0}〈100〉 slips. The CRSS in compression was higher particularly at low temperatures than the CRSS in tension. The tension-compression asymmetry on the CRSS was understood qualitativelys being due to the effect of the normal stress on the core structure of a 〈001〉 dislocation and a 〈111〉 dislocation. It was suggested that a compressive normal stress makes the core configuration more sessile, resulting in the increased stress effectively at low temperatures.     

退火均热时间对Fe-3.2 %Si无取向硅钢铁损的影响研究

研究了连续退火均热时间对Fe-3.2 %Si高牌号无取向硅钢P1.0/50和P1.5/50铁损性能的影响规律。结果表明：随着退火均热时间的增加,P1.0/50和P1.5/50均呈现先降低再升高的趋势,P1.0/50在110 s时最低值为1.008 W/kg,而P1.5/50在90 s时最低值为2.601 W/kg;当退火均热时间从50 s增加到130 s时,平均晶粒尺寸从70 μm增加至164 μm。均热时间短,{110}〈001〉取向晶粒尺寸小、数量多,其织构组分强度高;随着均热时间增加,γ纤维和{100}〈0vw〉、{110}〈001〉强度增强,但增幅逐渐变缓。在退火温度1 000 ℃×90 s工艺下,Fe-3.2 %Si可获得较优异的,P1.0/50和P1.5/50铁损性能和均匀性高的材料组织。     

Grain size effects on the texture evolution of α-Zr

The texture evolution during the plastic deformation at room temperature of Zr-2.5Nb round bars was studied in specimens with two different α-Zr grain sizes. It was found that during axisymmetric compression the strain producing mechanisms active during deformation depended on the grain size. In fine grained specimens there are two main phenomena characterizing the evolution of texture: (i) a rapid rotation of the grains about their 〈c〉 axis to form a <112¯0> fiber at strains below −0.20 and, (ii) a slow and progressive reorientation of the 〈c〉 axes of the grains towards the compression axis to form a [0001] fiber texture tilted approx. 20°. The latter process takes strains larger than −0.80. In coarse grained material, the texture evolution is characterized by a sudden rotation of the 〈c〉 axes to become aligned parallel to the compression axis at strains as low as −0.05. It is shown using a self-consistent viscoplastic model of texture evolution that the type of texture obtained depends on the mechanism controlling 〈c〉 axis deformation. In fine grained material prismatic slip, with basal and pyramidal 〈c + a〉 slip acting as complementary deformation modes, control the texture evolution process. In coarse grained material twinning is responsible for the final texture observed.