冷轧变形量及完全退火对汽车用5182板材组织和性能的影响

采用光学金相显微镜、万能力学试验机等测试分析手段,研究了冷轧变形量及完全退火对汽车用5182板材完全退火态(O态)组织和性能的影响。结果表明,退火时间2 h、退火温度300℃时板材再结晶不完全,360℃时发生晶粒二次长大,当退火温度330℃时,板材再结晶完全,晶粒呈多边形等轴状,大小均一,板材断后伸长率高,性能各向均匀,成形性能高;冷轧变形量为10%和25%时,O态板材晶粒粗大,拉伸后易形成橘皮缺陷,为65%时,晶粒细小,易形成明显吕德斯带应变缺陷,当变形量为45%时,O态板材晶粒大小为27μm,拉伸后无明显吕德斯带应变缺陷。冷轧变形为45%,330℃/2h完全退火后板材具有高的成形性能和表面应变质量的综合性能。     

基于RBF神经网络预测的多种晶粒度硬质合金磨削表面粗糙度研究

使用BLOHM ORBIT 25型精密平面磨床磨削纳米晶粒硬质合金GU092、超细晶粒硬质合金GU10UF和GU15UF、亚微米晶粒硬质合金GU20四种材料,研究磨削参数、晶粒度、Co含量与材料磨削表面粗糙度的关系。使用三元回归分析法探究磨削加工参数对合金表面粗糙度的影响,并用RBF神经网络预测纳米晶粒硬质合金的表面粗糙度,并对预测结果进行分析。结果显示：工作台速度和磨削深度与表面粗糙度呈正相关,砂轮线速度与表面粗糙度呈负相关;工作台速度对表面粗糙度影响最大,其次是砂轮线速度,影响最小的是磨削深度;硬质合金晶粒度越小,相同磨削参数下表面粗糙度越小;晶粒度相同但Co含量不同的硬质合金,Co含量越高,表面粗糙度越大;RBF神经网络对磨削表面粗糙度具有很高的预测精度。     

闪蒸法制备N型Bi2( Te0.95Se0.05)3薄膜的微结构及热电性能研究

采用闪蒸法在温度为473 K的玻璃基体上沉积了厚度为800 nm的N型Bi2(Te0.95Se0.05)3热电薄膜,并在373 ～573 K进行1h的真空退火处理.利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)分别对薄膜的物相结构和表面形貌进行分析.采用表面粗糙度测量仪测定薄膜厚度,薄膜的电阻率采用四探针法进行测量,采用温差电动势法在室温下对薄膜的Seebeck系数进行表征.沉积态薄膜表明了(015)衍射峰为最强峰,退火处理后最强衍射峰为(006);沉积态薄膜由许多纳米晶粒组成,晶粒大小分布较均匀,平均晶粒尺寸大约45 nm,退火处理后出现了斜方六面体的片状晶体结构.退火温度从373 K增加到473 K,薄膜的电阻率和Seebeck系数增加,激活能也随退火温度的增加而增大,退火温度从523 K增加到573 K,薄膜的电阻率和Seebeck系数都缓慢下降.从373 ～473 K,热电功率因子随退火温度的升高而单调增加,退火温度为473 K时,电阻率和Seebeck系数分别是2.7 mΩ.cm和-180μV·K-1,热电功率因子最大值为12 μW.cmK-2.退火温度从523 K增加到573 K,热电功率因子的值逐渐下降.     

电磁场对水平连铸锡磷青铜带质量的影响

在锡磷青铜QSn6．5—0．1带坯的水平连铸过程中施加交流电磁场可以改善铸坯的质量。未施加电磁场时，铸坯的晶粒较粗大，在670℃下需要7h以上的退火时间；施加电磁场后，铸坯的晶粒较细小，经5h退火即可获得很细小的晶粒组织，而且铸坯的抗拉强度降低、伸长率增加，有利于塑性加工，可减少带材表面裂纹的产生，并可望使铸造温度降低10-20℃。     

Fe-6．5％Si快速凝固极薄带

应用单辊快凝方法成功地制备出Fe-6．5%Si擞晶极薄带，并对其工艺参数和影响因素进行了研究。制得的这些极薄带的组织和磁性也进行了研究和分析。实验结果表明，铸态薄带表面光亮、平整并具有良好的冷轧延展性。铸态极薄带经1020～1070℃真空(真空度8×10^-4pa)退火1h，极薄带组织发生再结晶和异常晶粒长大，并出现(100)[ovw]面织构。遇火后的极薄带在400～3000Hz内展示出比通常Fe-3%Si薄带更优秀的软磁性能。     

再结晶退火对SPCC钢板组织和深冲性能的影响

通过实验室模拟工业罩式炉再结晶退火工艺,研究了退火温度和保温时间对SPCC钢板组织和深冲性能的影响,分析了退火后铁素体晶粒饼形度与深冲性能的关系。结果表明:随退火温度升高和保温时间延长,铁素体晶粒尺寸逐渐增大,同时深冲性能明显改善;700℃、保温4 h后晶粒尺寸和深冲性能再无明显变化。再结晶退火后铁素体晶粒饼形度与深冲性能有良好的对应关系,晶粒饼形度可以作为钢板深冲性能的判据之一。     

高温氩/氢混合气氛退火对硅片表面质量的影响

研究了高温退火过程中氩/氢混合气氛对300 mm硅片表面质量(原生颗粒缺陷和微粗糙度)的影响。在氢气含量不同的氩/氢混合气氛中,对样品进行1100℃,1 h的高温退火处理,研究退火前后硅片表面原生颗粒缺陷和微粗糙度值的变化。实验结果表明,氩/氢混合气氛中氢气的含量对硅片表面原生颗粒缺陷的消除没有促进也没有抑制作用,增加氢气比例能促进硅片近表层处空洞型缺陷的消除;混合气氛中氢气的存在使得退火后硅片表面的微粗糙度值增加的更多,同时随着氢气比例的增加,表面微粗糙度增加的百分比总体呈递增趋势。最后就氢气对硅片近表面处空洞型缺陷的消除促进作用和氢气至表面微粗糙度变化机制做了分析。     

快冷6.5%Si-Fe合金的织构和磁性

研究并讨论了快冷技术制备的薄带的晶粒结构及磁性能。实验结果表明:快冷技术具有技术简单和高效率的优越性。所制得的6.5％Si-Fe薄带银白色,平滑,易弯。铸态带为微晶(平均晶粒尺寸为5～15 μm),热处理大大改善薄带的晶粒织构和磁性。真空6.65 × 10~(-4) Pa中(1050～1100℃)1h退火,晶粒具有(100)(OK1)织构和最佳磁性P_(5/1k)=5.55W/Kg几乎与3％取向硅钢的磁性相同。用计算机回归分析方法得到P=af~nB~m公式,频率和磁感的变化范围分别是400 Hz～4 kHz和0.5～1.0 T。薄带表面氧化层会抑制(100)晶粒的二次再结晶,施加适当弹性形变会增强(100)晶粒的二次再结晶。我们认为等效表面能的降低是薄带中二次再结晶的驱动力。     

00Cr17Ti热带退火对冷轧薄板表面皱折的影响

 通过对00Cr17Ti经热带退火、不经热带退火两种工艺的冷轧板进行对比试验,在分析显微组织、织构的基础上,研究了热带退火对00Cr17Ti薄板表面皱折的影响。研究结果表明：与不经热带退火相比,经热带退火能使成品薄板的表面皱折大大减轻,最大粗糙度仅为12.06 μm,平均粗糙度仅为1.27 μm。两种工艺的成品板表面皱折程度的不同是由两者在显微组织、微织构上的差异造成的。与不经热带退火相比,经热带退火的成品薄板在板厚方向具有较均匀的组织,板宽方向的织构梯度较小,晶粒簇较间断、细窄、分散,所有这些使得成品薄板的表面皱折大大减轻。为了满足用户对薄板表面质量的严格要求,对热轧带进行退火是很有必要的。     

H68合金退火料温对其晶粒度的影响

本文对深冲用H68合金成品退火的晶粒度之影响因素进行分析,通过对原始晶粒度冷轧后（ε〉50%）的各种不同料温的晶粒度测试试验作出了不同料温情况下晶粒度的关系图,最后得出了两点结论,第一,H68合金板带的成品退火晶粒度不受原始晶粒度的影响,退火前冷加工率超过50%成品软态的晶粒度可获得最佳值;第二,H68合金板带的晶粒度与退火料温的关系是在550℃以下呈线性变化,大于550℃后变化不明显。     

Equilibrium grain-boundary segregation and the effect of boron in B-doped Fe−3wt%Ni austenitic alloy

The equilibrium segregation of boron at grain boundaries and the relation between grain boundary hardening and segregation in B-doped Fe−30 wt%Ni austenitic alloy were studied with the methods of microhardness measurement and Particle Tracking Autoradiography (PTA). It was found that equilibrium segregation of boron at grain boundaries appeared in the alloy as annealed between 650 and 960°C and no segregation of boron appeared above 1050°C. It could be concluded that an excess grain boundary hardening by addition of boron to the alloy was caused by the grain boundary segregation of boron.     

Effect of Annealing and Hot Rolling on Grain Boundary Segregation of Arsenic in an Mn-Steel Microalloyed by Ti,Cr and Nb

Steel samples with size of 10 mm×10 mm×5 mm were cut down from a hot-rolled Mn-steel microalloyed by Ti, Cr and Nb and produced by compact strip production (CSP) technology. The samples were annealed at 950 °C for different time firstly, and then hot rolled or cooled in the air, in water and in furnace, respectively. Auger electron spectroscopy (AES) was used to study the effects of annealing and hot rolling on the segregation of arsenic at grain boundary (GB) in the steel. The results indicated that a higher content of arsenic was found at grain boundaries than in the matrix when the steel was annealed at 950 °C for 2 h and then cooled to room temperature by water quenching. But the content of arsenic at grain boundaries was similar to that in the matrix when the steel was annealed at 950 °C for 2 h and then cooled to room temperature by furnace cooling. A longer holding time, such as 12 h and 36 h at 950 °C, resulted in a similar arsenic content at grain boundaries to that in the matrix of the steels. Hot rolling led to a similar content of arsenic at grain boundaries and within grains in the steels as well.     

Ni/Ni_3Al两相合金箔材的退火行为研究

研究了冷轧变形95%的Ni/Ni3Al两相合金箔材在经过100h退火后的再结晶过程以及织构和晶粒的微取向的变化。对其织构的测量未表现出如冷轧单相Ni3Al合金退火后所具有的织构记忆效应。EBSD(electron back-scattered diffraction)的测量结果显示退火后根据晶粒的取向可分为两个区域,一个区域的晶粒保持了与冷轧后试样的晶粒相同的取向,即其取向为(110),并且这一区域沿轧制方向呈带状分布,而另一个区域的晶粒的取向则为随机的。两个区域中(110)取向晶粒所占的百分比依次为57%和16%,并且在长时间退火后这种带状结构依然存在。冷轧变形95%的Ni/Ni3Al两相合金箔材在600～800℃之间退火时存在两种再结晶过程。一部分区域退火后生成大量的晶粒取向随机分布的再结晶晶粒,而在另一部分区域则其再结晶晶粒保持与冷轧织构相同的晶粒取向,并随着退火温度的升高而长大。     

Relation between ductility and grain boundary character distributions in Ni3Al

The grain boundary character distributions in cast, recrystallized and strain annealed Ni₃Al alloys with a composition of Ni23Al were examined to clarify the relation between ductility and the grain boundary character distributions in Ni₃Al. The percentages of CSL boundaries in cast, recrystallized and strain annealed Ni₃Al alloys are 26.8, 43.1 and 58.4%, respectively, of the total number of boundaries examined. The sum of the percentages for LAB (Low Angle Boundary) and Σ3 boundary in cast, recrystallized and strain annealed Ni₃Al alloys is 4.46, 10.8 and 29.2% respectively. This indicates that strain annealing is effective in enhancing the frequency of occurrence of CSL boundaries, especially LAB and Σ3 boundary, in Ni₃Al. The strain annealed Ni₃Al alloy having a much higher frequency of CSL boundaries is found to exhibit elongation to fracture of more than 45%. This significant increase in elongation of the strain annealed Ni₃Al alloys is attributed to the presence of relatively low energy LAB and Σ3 boundaries.     

Some observations of grain boundary ledges and ledges as dislocation sources in metals and alloys

Direct observations of grain boundary ledges have been made in annealed Ni, Al, Cu, Mo, Ta, Ir, 304 Stainless Steel and Inconel 600 by transmission electron microscopy. Grain boundary ledges have been observed to be sources of dislocations during and after plastic deformation, and to resemble the appearance of dislocation pileups in the transmission electron microscope. Ledge density (number per unit length of grain boundary) has been observed to increase with an increase in grain boundary misorientation in Ni and 304 Stainless Steel, and the distribution of misorientations was observed to be continuous over the range 0 deg <θ< 90 deg at an annealing temperature of 1060°C. The mean grain boundary misorientation in 304 Stainless Steel was also observed to decrease with a decrease in the recovery temperature following cold reduction and to vary from 10 to 45 deg in the temperature range of 660 to 1060°C. An essential point of this investigation is that Li’s theoretical treatment of the flow-stress, grain-size relation based on the existence of grain boundary ledges and their action as sources of dislocations under stress is shown to be correct.     

The dependence of normal and abnormal grain growth in silver on annealing temperature and atmosphere

When polycrystalline pure Ag specimens are compressed to 40 pct and annealed, there is no noticeable texture in the recrystallized structure, and normal or abnormal grain growth occurs during annealing. When annealed further in low vacuum (10⁻³ to 10⁻⁴ Torr) after the completion of recrystallization, normal grain growth occurs at 920 °C and 800 °C, but abnormal grain growth (AGG) occurs at 700 °C, 600 °C, and 500 °C. When annealed in O₂ atmosphere, normal grain growth occurs at 920 °C and AGG at 800 °C, 700 °C, 600 °C, and 500 °C. At temperatures close to the melting point (960.5 °C), the grain boundaries are expected to be rough at atomic scales and hence have nearly isotropic boundary energy. The normal growth of the grains with such atomically rough boundary structures is consistent with some theoretical analysis and simulation. At low temperatures, the grain boundaries can be faceted with probably singular structures. Because these grain boundaries apparently migrate by the movement of boundary steps, AGG occurs. The observations with optical microscopy indeed indicate that some grain boundaries are faceted at low temperatures and all of them are smoothly curved indicating an atomically rough structure at high temperatures close to the melting point. Although the results are not conclusive, they support the hypothesis that AGG occurs because the faceted singular grain boundaries migrate by the step mechanism.     

Mechanical properties of iron processed by severe plastic deformation

In the present study, the mechanical properties of Fe processed via severe plastic deformation (equal-channel angular pressing (ECAP)) at room temperature were investigated for the first time. The grain size of annealed Fe, with an initial grain size of about 200 μm, was reduced drastically during ECAP. After eight passes, the grain size reaches 200 to 400 nm, as documented by means of transmission electron microscopy (TEM). The value of microhardness during pressing increases 3 times over that of the starting material after the first pass and increases slightly during subsequent pressing for higher-purity Fe. Examination of the value of microhardness after eight passes as a function of post-ECAP annealing temperature shows a transition from recovery to recrystallization, an observation that resembles the behavior reported for heavily deformed metals and alloys. The tensile and compression behaviors were examined. In tension, a drop in the engineering stress-engineering strain curve beyond maximum load was observed both in the annealed Fe and the ECAP Fe. This drop is related to the neck deformation. The fracture surface, examined by scanning electron microscopy (SEM), shows vein patterns, which is different from the dimples found on the fracture surface of annealed Fe. In compression, an initial strain-hardening region followed by a no-strain-hardening region was observed in the ECAP Fe. The yield strength in tension of the ECAP Fe was observed to be higher than that in compression. The strengthening mechanisms and softening behavior are discussed.     

Some observations of grain boundary ledges and ledges as dislocation sources in metals and alloys

Direct observations of grain boundary ledges have been made in annealed Ni, Al, Cu, Mo, Ta, Ir, 304 Stainless Steel and Inconel 600 by transmission electron microscopy. Grain boundary ledges have been observed to be sources of dislocations during and after plastic deformation, and to resemble the appearance of dislocation pileups in the transmission electron microscope. Ledge density (number per unit length of grain boundary) has been observed to increase with an increase in grain boundary misorientation in Ni and 304 Stainless Steel, and the distribution of misorientations was observed to be continuous over the range 0 deg <θ< 90 deg at an annealing temperature of 1060°C. The mean grain boundary misorientation in 304 Stainless Steel was also observed to decrease with a decrease in the recovery temperature following cold reduction and to vary from 10 to 45 deg in the temperature range of 660 to 1060°C. An essential point of this investigation is that Li’s theoretical treatment of the flow-stress, grain-size relation based on the existence of grain boundary ledges and their action as sources of dislocations under stress is shown to be correct.     

Grain boundary structural changes during annealing and high temperature deformation of ferritic stainless steel

Grain boundary structure and energy have an influence on the formation of the annealing texture as well as the material ability to continue the steady state deformation at high temperatures. Texture measurements together with the statistical distribution of grain boundary rotation parameters show changes during high temperature deformation. Annealed structure contains grain boundaries having rotation parameters in certain favoured groups. Such groups do not necessarily belong to any low indexed coincidence orientation relationship, even though periodic contrast of grain boundary dislocations in numerous boundaries is resolved in the transmission electron micrographs. The texture becomes stronger during the high temperature deformation with increasing strain compared with the annealed texture. The rotation parameters of grain boundaries in deformed structure include often few degrees rotations from certain coincidence orientation relationship, but they do not, however, show such a grouping of rotation parameters as in the annealed structure. Furthermore, rotation angles of small angle boundaries were found to increase with increasing deformation strain at high temperature. Several mechanisms of grain boundary sliding are interpreted based on the structural observations. Finally, based on the existence of orientation relationship groups, estimates for low energy grain boundaries are presented.