IF钢铁素体区热轧和退火过程中织构的演变

研究了一种Ti—IF（Interstitial—free）钢在铁素体区热轧和退火过程中织构的变化．由于轧制过程摩擦的影响,热轧织构和退火织构在厚度方向上都有很大的差异．在钢板的表层,热轧织构的主要组分是{110}（001）,退火后表层的铁素体晶粒没有发生再结晶,该组分转变为（001）（110）;在试样的中心和1／4面,热轧织构组分主要是较弱的（111）／／ND（板法向）织构和部分（110）／／RD且在{001}（110）处最强;退火后中心面上的晶粒发生了完全再结晶,{001}组分转变为（111）／／ND组分使（111）／／ND织构成为唯一织构组分且在{111}（112）处最强．     

高强Ti-IF钢铁素体区热轧和冷轧过程织构演变规律

为了揭示铁素体区热轧、冷轧和退火过程中高强Ti-IF钢中织构的演变过程,采用X射线衍射仪研究了铁素体区热轧及随后的冷轧和退火织构的特点.研究表明,在铁素体区热轧后,表面和中心面的织构类型和强度不尽相同,表面上的主要织构组分是剪切织构{110}<001>,而中心面上的主要织构组分是{001}<110>～{223}<110>和{111}<110>,由于织构的遗传性,冷轧和退火后的织构在表面和中心面上也不相同;经不同压下率冷轧后,织构变化趋势一致,表面上{110}<001>组分消失,{001}<110>成为最强组分,而中心面上最强组分由{001}<110>沿α取向线向{112}<110>偏移,冷轧织构由α织构和γ织构组成;退火后,表面上织构的变化与以往结论有所不同,{001}<110>～{112}<110>组分减弱,而γ取向线上的{111}<123>组分增强,{111}<112>和{111}<110>减弱.     

Design of texture for improved formability of high-strength steel

The effect of crystallographic textures on the formability of BCC steel sheets has been studied by using crystalline plasticity finite element analysis (FEA) and experiments. It was confirmed that one of the important reasons why the conventional high-strength steel sheet has poor formability was due to lack of {111} fiber texture components —γ-fiber texture—. In this paper, a texture adjusted design method is proposed to improve the formability of conventional high-strength steel sheets. First, an artificial γ-fiber texture is defined in terms of a rotationally symmetric Gaussian distribution of deviation angles, which has a certain scatter width along the given γ-fiber skeleton line in Euler space. The analytic textures are designed by introducing the artificial γ-fiber texture into the conventional high-strength steel model. The blending coefficient corresponding to the {111}/{001} volume fraction ratio is selected as the design parameter. Then, an optimum crystallographic texture of steel sheet is found through the limit dome height (LDH) formability tests by employing as objective function, which is evaluated by a maximum thinning ratio of the deformed sheet. Further, it is demonstrated that the sheet with the optimum texture shows the best straining in VDI benchmark stamping tests.     

Effect of Coiling Temperature on the Evolution of Texture in Ferritic Rolled Ti-IF Steel

The effect of coiling temperatures on the evolution of texture in Ti-IF steel during ferritic hot rolling, cold rolling and annealing was studied. It was found that texture evolution at high temperature coiling is absolutely different from that at low temperature one. The hot band texture includes a strong α-fiber as well as a weak γ-fiber after ferritic hot rolling and low temperature coiling. Both of them intensify after cold rolling and a γ-fiber with peak at {111}〈112〉 is the main texture of annealed samples. However, the main component of the hot band texture after high temperature coiling is v-fiber. After cold rolling, the intensity of γ texture reduces; α fiber （except {111}〈110〉 component） intensifies and a strong and well-proportioned γ-fiber forms in the annealed samples.     

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 λ 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 ～41?μm 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.     

深冲IF钢再结晶{111}纤维织构形成机制探讨

为了探讨深冲IF钢再结晶织构与退火温度之间的关系及{111}再结晶织构形成机制,采用X射线衍射三维取向(ODF)和背散射电子衍射(EBSD)分析技术并结合金相组织观察,利用Gibbs-Thom son方程对冷轧IF钢在不同退火温度下的再结晶织构演变规律及形成机制进行研究.实验结果表明:随着退火温度的增加,再结晶量逐渐增多,γ纤维织构强度亦相应增强,同时,α纤维织构强度则逐渐降低;冷轧IF钢再结晶初期的织构转变主要发生在γ纤维织构之间.研究表明,再结晶核心的形成主要以"显微择优形核"为主,晶核的长大则主要以择优生长为主,而Σ重位点阵晶界在再结晶γ纤维织构形成过程中起着重要作用.     

EBSD Investigation on Oriented Nucleation in IF Steels

The mechanism responsible for the formation of recrystallization texture in cold-rolled Ti bearing interstitial free （IF） steel sheets was investigated using electron back-scatter diffraction （EBSD）. In addition, the origin of nuclei with specific orientations was studied. The formation of recrystallization texture was explained by oriented nucleation. Most nuclei have a high misorientation angle of 25-55° with the surrounding deformed matrices, but no specific orientation of misorientation axis between the nucleus and the surrounding deformed matrix is observed. The stored energy of deformed grains is in the decreasing order of the {111}〈112〉,{111}〈110〉, {112}〈110〉 and {001}〈110〉 orientations. New {111}〈110〉 grains are nucleated within deformed {111}〈112〉 grains and new {111}〈112〉 grains originate in the deformed {111}〈110〉 grains.     

Recrystallisation textures in cold rolled low carbon steel containing ferritic and bainitic microstructures

Abstract

Low carbon steel strip was heat treated to generate four different starting microstructures (fine and coarse polygonal ferrite, acicular ferrite and bainite) for investigating their influence on texture development during cold rolling and annealing. The starting materials were cold rolled to 50–90% reduction and annealed for various times in the temperature range 853–953 K. The resultant microstructures and textures were examined mainly by electron backscatter diffraction and X-ray diffraction. The initial microstructure strongly influenced the crystallographic rotation paths during cold rolling, whereby high strain deformation generated strong {223}〈110〉 texture components in the polygonal ferritic microstructures, whereas a strong {001}〈110〉 texture was produced in the acicular/bainitic microstructures. Subsequent annealing generated, to varying degrees, the classic {111}〈uvw〉 (γ-fibre) recrystallisation texture in all materials. Unexpectedly, coarse polygonal ferrite produced the strongest γ-fibre recrystallisation texture after 70–90% cold rolling reduction. Based on arguments involving the effect of carbon in solution, initial grain size and deformation textures on recrystallisation texture development, it was shown that a strong γ-fibre texture can indeed be generated in coarse polygonal ferrite.     

Effect of substrate temperature on the texture and structure of polycrystalline Si0.7Ge0.3 films deposited on SiO2 by molecular beam deposition

The evolution of microstructure and texture of molecular beam deposited Si_0.7Ge_0.3 films on SiO₂ at the deposition temperature range of 400–700°C was investigated by X-ray diffraction and transmission electron microscopy. At deposition temperatures between 400 and below 500°C, the films were directly deposited as a mixed-phase on SiO₂ and have a inversely cone-shaped structure. In this temperature range deposited as a mixed-phase, the grain size increases as the temperature increases, so that the grains not only grow up by deposition, but also laterally grow by the solid phase crystallization, furthermore, the texture is changed from a {110} texture to mixed {311} and {110} textures. At 500°C, the film was deposited as only a crystalline phase and has a columnar structure with a strong {110} texture. In the temperature range of 500–700°C, as the temperature increases, the {311} and {111} textures develop whereas the {110} texture reduces. The film deposited at 700°C has a random orientation and structure.     

GH4169合金楔横轧加工过程中动态再结晶及织构演变

为研究GH4169合金楔横轧加工过程中动态再结晶及织构演变规律,采用金相显微镜(OM)和电子背散射衍射(EBSD)对30%,50%两种断面收缩率下GH4169合金楔横轧件表层与心部的微观组织、晶体取向及织构进行分析。结果表明:GH4169合金楔横轧加工过程中,随着动态再结晶的发生,晶体取向逐渐变得随机化分布;轧制表层大角度晶界数量较轧件心部多,轧件表层织构强度变化不大,心部织构强度明显增强;经过楔横轧变形后织构发生转动,原始态织构类型为{001}〈110〉,{111}〈110〉,{111}〈011〉,轧制后主要织构类型为{001}〈010〉,{112}〈110〉,{110}〈111〉,{110}〈112〉;GH4169合金楔横轧件动态再结晶及织构演变规律是由楔横轧特殊变形特点决定的。     

加磷高强Ti-IF钢的最优卷取温度和冷轧压下率的确定

以工业生产的加磷高强Ti-IF钢为试验材料,在实验室研究了卷取温度和冷轧压下率对试验钢显微组织、力学性能和织构的影响.结果表明:在试验条件下,试验钢在不同冷轧压下率下,卷取温度在550～600℃时,再结晶完成;不同卷取温度下,随着冷轧压下率的增加,晶粒变得细小均匀;卷取温度在600℃时,不同冷轧压下率下的屈服强度、抗拉...     

罩式退火无间隙原子钢的最优冷轧压下率的确定

以工业生产的含钛、铌和含钛的两种无间隙原子(IF)钢热轧钢板为试验材料,在实验室研究了冷轧压下率对两种IF钢的显微组织、力学性能和再结晶织构的影响。结果表明:在试验条件下,两种试验钢经不同冷轧压下率冷轧和720℃×5 h罩式退火后,再结晶完成,随着冷轧压下率的增加,晶粒变得细小均匀,退火后得到的织构也增强,并且织构类型有转向{111}织构的趋势;塑性应变比r90在压下率为70%时达到最大值,随着冷轧压下率的进一步增大,r90值减小;应变硬化指数n90值逐渐降低。最后提出工业生产中冷轧压下率最佳范围为70%~80%,可获得良好的深冲性能。     

Research on Deformation, Texture and Properties of IF Steel in Multiple Rolling Technology

The relationships among the deformation, texture and deep drawing properties of IF steel were investigated. By adopting double cold rolling (DCR) technology, the deep drawing property has been developed evidently. With the aid of orientation distribution function (ODF) analysis, it was found that he main reason for good property is the counterbalance in intensity of the ideal texture component {111} < 011 > and {111} < 112 >.     

Texture development in cold rolled and annealed C-Mn-Si and C-Mn-Al-Si TRIP steels

Abstract

The texture of two transformation induced plasticity steels has been studied by means of crystallographic orientation mapping. Texture measurements were carried out on ferrite, bainite, and austenite. The polygonal ferrite and the bainite texture, both bcc, could be distinguished based on the image quality parameter of the electron backscattering diffraction measurement. Both bcc textures were very similar, the main difference being the more pronounced 111alpha ND ND=normal direction and 110alpha RD RD=rolling direction fibre textures in the polygonal ferrite. The fcc texture was a strong gamma deformation texture, characterised by the beta fibre. The presence of the alpha fibre confirmed the strong 110gamma ND direction, which was previously detected by means of X ray diffraction XRD. The measured fcc and bcc textures were used to calculate orientation distribution function transformations according the Bain, Kurdjumov-Sachs, and Nishiyama-Wasserman orientation relationships. The predicted cube component {001}gamma 100gamma, which was missing in the measured texture, of gammaret indicates a variant selection for the gammaalphaB transformation. In addition it was shown that crystallographic orientation mapping could be used to make reliable phase fraction determinations, which were previously based on the light optical microscopy of colour etched specimens. This also proves that XRD determination of gammaret is flawed owing to the strong texturing of all phases present in the microstructure.     

高强IF钢板沿厚度方向的织构和显微组织

利用X射线三维取向分布函数(ODF)方法和金相方法分别对加磷强化的高强IF钢沿厚度方向织构和显微组织的不均匀性及其变化规律进行了研究。结果表明:该高强IF钢板厚度中心层的γ纤维织构强度及体积分数最高,其次为1/4厚度层,最弱为表层;钢板的显微组织则由表层大小不均匀的晶粒逐渐转变为中心层大小非常均匀的等轴晶粒;这种织构和显微组织沿厚度方向的不均匀现象是由于在轧制过程中钢板的变形不均匀性所造成的。     

3%Si电工钢铸坯中柱状晶的形变、再结晶行为及织构演变规律

利用电子背散射衍射(EBSD)技术和X射线衍射仪(XRD)研究3%(质量分数)Si电工钢铸坯中柱状晶的形变、再结晶行为及织构演变规律。结果表明:柱状晶长轴分别沿轧向、横向和法向放置,具有不同的初始织构。热轧后,表层形成的3种剪切取向中高斯取向较容易形成。中心区,RD样品中的α和γ线轧制取向,TD样品中的强γ线取向,ND样品中的强{100}取向以及各样品中的立方取向,均表现出明显的初始取向依赖性。冷轧后,RD,TD样品中的强{111}〈112〉取向来自热轧板中的高斯取向,ND样品中的强旋转立方取向遗传自初始{100}取向。受初始取向偏差及大晶粒尺寸影响,ND样品中的旋转立方取向晶粒内取向梯度较大。退火后,样品中心大尺寸的{100}取向晶粒是柱状晶初始取向遗传性的表现。     

温轧温度对Cr-Ti-B系低碳钢组织与织构的影响

使用扫描电镜、电子背散射衍射、透射电子显微镜和固体内耗仪研究了温轧温度对Cr-Ti-B系低碳钢组织和织构的影响.结果 表明,温轧后钢的组织由变形铁素体和少量珠光体所组成,随着温轧温度的提高铁素体晶内剪切带的含量呈现先提高后降低的趋势,在450℃温轧剪切带的含量最高.剪切带的形成,与Ti和B元素的偏聚密切相关.在350℃...     

Characterization of microstructure,texture and magnetic properties in twin-roll casting high silicon non-oriented electrical steel

An Fe-6.5 wt.% Si-0.3 wt.% Al as-cast sheet was produced by twin-roll strip casting process, then treated with hot rolling, warm rolling and annealing. A detailed study of the microstructure and texture evolution at different processing stages was carried out by optical microscopy, X-ray diffraction and electron backscattered diffraction analysis. The initial as-cast strip showed strong columnar grains and pronounced < 001 >//ND texture. The hot rolled & warm rolled sheets were characterized by large amounts of shear bands distributed through the thickness together with strong < 110 >//RD texture and weak < 111 >//ND texture. After annealing, detrimental < 111 >//ND texture almost disappeared while beneficial {001}<210 >, {001}<010 >, {115}<5 − 10 1 > and {410} < 001 > recrystallization textures were formed, thus the magnetic induction of the annealed sheet was significantly improved. The recrystallization texture in the present study could be explained by preferred nucleation and grain growth mechanism.     

TEXTURE DEVELOPMENT IN EXTRA LOW CARBON (ELC) AND INTERSTITIAL FREE (IF) STEELS DURING WARM ROLLING

The warm rolling and subsequent annealing textures of an extra low carbon (ELC) and two interstitial free (IF) steels have been investigated using both single pass and multipass rolling in the ferritic temperature range. A total amount of 80% deformation by rolling was given in each case. It was observed that texture development in ELC and IF steels during warm rolling displays striking differences. In general, ELC steels acquire only a weak texture after finish rolling in the upper ferritic range, for both single and multipass rolling. Single pass warm rolling in the lower ferritic range, however, produces very sharp γ fiber in this alloy, as an exception. Recrystallization anneal after warm rolling, in general, has been found to decrease the overall texture. By contrast, much sharper overall texture (and γ fiber) develops in the IF steels during warm rolling, and it generally sharpens after subsequent recrystallization anneal. This is true for both single pass and multipass rolling. The best texture results (highest intensities of γ fibers) are invariably obtained when most of the rolling deformation is given in the ferritic regime. Thus, between the two grades, the IF steels are definitely far better than the ELC steels for the purpose of developing sharp γ fibers by warm rolling process. Out of the two IF steels, the Ti-containing steel appears to develop a perceptibly sharper γ fiber after warm rolling and annealing as compared to the Nb-containing one.     

A study of recrystallisation textures in hot band of a continuous cast Al–Mn–Mg alloy

Abstract

The hot band of a commercial continuous cast (CC) Al–Mg–Mn alloy was annealed at different temperatures ranging from room temperature to 510°C for 3 h. The evolution of microstructure and crystallographic texture was investigated during the annealing treatment. It was found that the recrystallised alloy exhibited a severely elongated grain structure and a texture that consisted of a new type of component ({113}〈110〉) and two fibre components (〈100〉//ND and 〈110〉//ND), the axes of which were along the normal direction of the rolling plane (ND) in 〈100〉 and 〈110〉 respectively. The 〈100〉//ND fibre was dominated by a ND rotated cube orientation {001}〈310〉, while the 〈110〉//ND fibre was mainly composed of Goss and P orientation ({011}〈566〉). The formation of the {113}〈110〉 texture and two fibre textures was likely to be attributed to the concurrent precipitation effect taking place upon heating in annealing treatment of the alloy.