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1.
试验研究了取向硅钢(/%:0.046C,3.07Si,0.09Mn,0.029P,0.004S,0.005 Al,0.001Ti,0.001 40,0.009 6N)2.66 mm热轧板1 100℃2 min空冷10 s至960℃3min空冷常化后,经一次冷轧,中间退火,二次冷轧0.3 mm板,820℃5 min空冷初次再结晶退火,并经1 050℃空冷二次再结晶退火后的组织、织构和磁性能。通过对比常化和无常化样品的初次再结晶退火后试样以及二次再结晶退火后试样的组织和性能,得出常化工艺对退火过程的影响。结果表明,热轧板常化处理可以降低冷轧板初次退火后的初次再结晶晶粒尺寸,使∑9晶界和大角度晶界百分含量增加,高斯取向晶粒含量增加,还可以使二次再结晶晶粒增大,提高磁感应强度、降低铁损。 相似文献
2.
IF钢罩式退火与连续退火再结晶模拟试验 总被引:3,自引:0,他引:3
对IF钢罩式退火(BA)和边续退火(CA)的再结晶过程进行了模拟试验与分析,结果表明:BA工艺的再结晶中晶粒有一个从饼状晶粒向等轴晶粒转变的过程;而CA工艺的再结晶过程中再结晶晶粒一开始就呈等轴状,而后逐步不断长大。 相似文献
3.
摘要:以在650℃温轧的Fe-24Mn-2Al-1Si-0.05C TWIP钢为研究对象,通过金相显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、室温拉伸等实验手段,研究温轧TWIP钢在回复退火、部分再结晶退火、高温短时退火以及高温退火等不同退火工艺下其微观组织及力学性能的演变。结果表明,随着退火工艺的改变,实验钢的微观组织由回复退火时包含高密度位错、形变孪晶等的变形晶粒逐渐向高温退火时的无畸变再结晶晶粒转变;而部分再结晶退火时,实验钢的微观组织由未再结晶区的变形晶粒和细小的再结晶晶粒混合组成。随退火工艺的改变,实验钢拉伸前、后的硬度变化趋势为先下降然后基本不变最后上升;实验钢的变形机制逐渐由位错滑移为主向孪生滑移为主转变。 相似文献
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Yanqing Feng 《冶金译丛》2014,(2):64-67
本文对比研究了Ti-IF钢罩式退火工艺下的再结晶规律及连续退火工艺下再结晶规律。分别采用随炉升温到不同温度测定再结晶规律,和采用到温入炉保温100s出炉测定再结晶规律。模拟罩式退火采用两阶段随炉升温,所测试样的名义再结晶温度为620,实际的再结晶温度为660℃,实验钢在随炉升温至660℃下完成再结晶过程历时68min;700℃、720℃再结晶的新晶粒开始长大;800℃时,再结晶的晶粒等轴化。模拟连退采用快速升温到不同温度,试样到温入炉保温100s出炉空冷,660℃再结晶开始形核,700℃形核的数量开始增加,720气:形核数量急剧增加,800 ~840℃再结晶晶粒长大,晶粒均匀化,900℃发生二次再结晶,晶粒反常长大。 相似文献
6.
本文通过对晶粒长大及再结晶过程的分析找出了H68TM带退火工艺的理论依据,最终实现了对H68TM带的晶粒度控制。 相似文献
7.
用二维元胞自动机方法 ,以 0 .0 2 %C铝镇静钢深冲板St15热轧、冷轧、退火再结晶组织和织构以及再结晶演变的实验结果为初始条件和参照 ,分别对 1.2mm冷轧深冲板 5 6 0~ 6 2 0℃退火再结晶和 70 0℃晶粒长大过程进行计算机模拟。得出 ,冷轧深冲板 5 6 0~ 6 2 0℃加热 12 0min再结晶完成 ,平均再结晶晶粒为 6μm ,再于 70 0℃加热 10h ,晶粒长大尺寸和织构趋于稳定 ,平均晶粒尺寸为 34μm ,织构以有利织构组分 { 111}〈110〉和 { 111}〈112〉织构为主。模拟结果与实验数据相符 相似文献
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以纯度为99.95%的钨粉为原料,在200 MPa压力下冷等静压成形,2 300℃于H2气氛中进行烧结制得钨烧结坯。钨烧结坯在1 250~1 500℃于H2气氛中经过4道次轧制制得接近理论密度的钨板。通过金相、维氏硬度和高温拉伸强度分析了轧制过程和退火过程中钨板组织和性能的变化规律。通过电子背散射衍射(EBSD)分析了退火过程中钨板织构的衍变。结果表明:轧制过程中钨板的密度、维氏硬度和高温抗拉强度随材料变形量的升高而增大,经过4道次轧制钨板的密度可接近理论密度,维氏硬度和高温抗拉强度分别为HV450和540 MPa;轧制态的钨板晶粒组织有明显沿RD方向拉长,1 350℃退火时,形变织构明显减弱,晶粒取向分布趋于随机。通过统计面积分数分析得到1 350℃钨板晶粒再结晶组织比例占65.8%。 相似文献
11.
The level of surface-carbon contamination exerts an adverse influence on the subsequent coating process such as phosphating and painting. In evaluating quantitatively surface carbon by the combustion technique, the temperature programmes adopted do not exceed 500°C in the case of sheet produced by continuous annealing system and 600°C for batch-annealed sheet, this to avoid matrix-carbon combustion. In this paper two hypotheses are discussed, concerning the reasons why evolution of the matrix carbon occurs at different temperatures in the two types of steel products. It is shown that different grain sizes generated by the batch and continuous annealing processes induce diversity in the different surface reactivities, in fact, grain size and hence the concentration of surface grain boundaries increases the oxidation rate of carbon. 相似文献
12.
Fusheng Sun Alejandro Zúñiga Paula Rojas Enrique J. Lavernia 《Metallurgical and Materials Transactions A》2006,37(7):2069-2078
The grain growth, thermal stability, and recrystallization behavior of a cryomilled Ti alloy with a grain size of about 21.2
nm were examined using differential scanning calorimetry, X-ray diffraction, and transmission electron microscopy. Isochronal
heat treatments at different temperatures were applied to study the thermal stability and recrystallization behavior of this
alloy system. The average grain size increased from 20 to 80 nm in the temperature range of 200 °C to 350 °C, and then significantly
decreased to 15 nm during annealing at 400 °C to 450 °C. This phenomenon was rationalized on the basis of a recrystallization
mechanism. When the annealing temperature increased from 450 °C to 720 °C, the grain size increased slightly from 15.2 to
27.5 nm. In addition, the isothermal grain growth behavior in this alloy was investigated in the temperature range of 150
°C to 720 °C, and the resulting grain growth activation energy was analyzed to rationalize the underlying grain growth mechanisms.
An interesting scientific question that arises from the present work is whether a decrease in grain size can be obtained in
nanocrystalline (nc) materialsvia a recrystallization mechanism. The present results show that indeed a smaller grain size is obtained after annealing at elevated
temperatures (500 °C to 720 °C) in cryomilled nc Ti, and the experimental results are explained on the basis of a recrystallization
mechanism. 相似文献
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For ultra low carbon (ULC) and low carbon steel (LC), the influence of heating rate, annealing temperature, and holding time on the recrystallisation behaviour and the resulting grain size was investigated. For ULC smallest grain sizes of about 9 μm were obtained at the lowest heating rate whereas for LC significant smaller grain sizes of about 5 μm were determined at the highest heating rate. Furthermore, the evolution of the grain size distribution with varying heating rate, annealing temperature, and holding time was studied in dependence of the rolling and normal direction. The state of the as‐hot rolled microstructure as well as the precipitation state exert a strong influence on the development of the recrystallised microstructure along the different directions for both steel grades. The inherent prolonged microstructure due to the cold rolling process is still obvious just after recrystallisation. With ongoing annealing and grain growth, the aspect ratio approaches the equiaxed state. This change proceeds faster for the ULC steel grade. With increasing annealing temperature, the bimodal character of the grain size distribution disappears and the distribution becomes more homogeneous. 相似文献
15.
Ming-Chun Zhao Toshihiro Hanamura Hai Qiu Ke Yang 《Metallurgical and Materials Transactions A》2006,37(5):1657-1664
The microstructural evolution of submicron sized ferrite in bimodal structural ultrafine grained ferrite/cementite steels
with 0.15 pct carbon content and 0.45 pct carbon content upon annealing below the austenized temperature was investigated.
The average grain sizes of the ferrites with a normal density and with a high density of cementite particles were plotted,
respectively, as a function of the annealed temperature and time, and exhibited different coarsening behaviors. The average
grain sizes of the ferrites with a normal density of cementite particles gradually coarsened by increasing the annealing temperature
or time, while those with a high density of cementite particles hardly changed at first, and then coarsened after reaching
a certain annealing condition. The coarsening of the ferrite grain size in the steel with 0.15 pct carbon content occurred
much more readily than that in the steel with 0.45 pct carbon content upon annealing. The spacing and the critical spacing
of cementite particle were measured and hypothetically calculated, respectively. The size and the distribution of cementite
particles was one of the critical factors affecting the microstructural evolution in this type of cementite particle spherodized
steels. Most of the coarsening of the ferrite grain size occurred after the cementite particle spacing reached the required
critical value. 相似文献
16.
为解决GH4169合金带材国产化制备工艺不成熟导致的组织及性能控制不稳定问题,对厚度为0.4 mm的GH4169合金带材的热处理工艺进行研究。讨论了不同退火温度、不同保温时间对带材金相组织、力学性能的影响,结果表明,退火温度对带材显微组织和力学性能存在显著影响,随着退火温度的提高,合金带材晶粒尺寸增大,同时合金抗拉强度、屈服强度和硬度呈下降趋势,而伸长率呈升高趋势;适当缩短保温时间可以使晶粒尺寸均匀,并起到细化晶粒的作用,与此同时,合金力学性能表现出抗拉强度、屈服强度和硬度增大,同时伸长率呈下降趋势。综合分析组织及性能,0.4 mm的GH4169合金带材最佳退火工艺为退火温度1 050℃、保温时间1.5 min,在该工艺下带材的晶粒度为8.5级,抗拉强度为870.5 MPa,屈服强度为389.5 MPa,伸长率为51.5%,维氏硬度为204HV1。 相似文献
17.
《Acta Metallurgica Materialia》1995,43(9):3325-3332
Thermal expansion behaviors of nanocrystalline (NC) Ni-P alloy samples with grain sizes ranging from a few to 127 nm were studied experimentally using thermal mechanical analysis. Porosity-free NC Ni-P samples with a wide grain size range were synthesized by completely crystallizing amorphous Ni-P alloy at different annealing temperatures. Measurements showed that the linear thermal expansion coefficient (αL) increases markedly with a reduction of the average grain size in the as-crystallized NC Ni-P samples. The thermal expansion coefficient was also found to decrease during grain growth in the as-crystallized NC sample upon annealing. From the grain size dependence of αL in these NC samples, we deduced that the difference in thermal expansion coefficients between the interfaces and the nm-sized crystallites diminishes when the grain size becomes smaller. This tendency agrees well with other experimental results on the structural characteristics of the interfaces and the nm-sized crystallites in NC materials. 相似文献
18.
C. C. Bampton J. A. Wert M. W. Mahoney 《Metallurgical and Materials Transactions A》1982,13(2):193-198
A method has previously been described whereby a fine and stable grain size may be achieved in conventional, heat-treatable
aluminum alloy sheet by thermomechanical processing. The present work has examined the final recrystallization stage more
closely. In particular, the effects of heating rate on recrystallized grain size have been determined and explained. It has
been shown that heating rates greater than about 5 K . s-1 should be employed in the final recrystallization stage in order to obtain maximum benefit from the fine grain processing
technique. The coarser recrystallized grain sizes obtained with slower heating rates are mainly due to early activation of
the most highly favored nucleation sites. Thermal recovery of the matrix defect structure below the recrystallization temperature
is an additional, though less significant, effect. The influence of the degree of cold work and the volume fraction of insoluble
particles on recrystallized grain size is discussed in relation to the heating rate. 相似文献
19.
Mohammad Tajally Esmaeil Emadoddin Ehsan Allah Shahi 《Russian Journal of Non-Ferrous Metals》2014,55(5):429-435
Quantitative understanding of the process and formability parameters involved in grain size and the formation of annealing twins after plastic straining is important in the control of the manufacturing process. There is a synergistic effect of strain and temperature on the density of annealing twins. Formability of brass alloy sheets was studied after annealing of 65% cold worked (CW) samples at different temperatures (300–600°C). Tensile, deep drawing and Erichsen tests were carried out at room temperature to evaluate formability of alloy. Effect of annealing temperature on density, distribution and size of twins is investigated. It was shown that annealing of brass alloy resulting in formation of annealing twins which at higher annealing temperature were reduced by increasing grain size. Best deep drawability would be achieved by annealing at moderate temperature 400–450°C which microstructure consists of fine grain and twin bands. Work hardening exponent of samples was calculated based on the tensile test data and correlated with stretch ability of annealed brass sheets. It was found that the sheets annealed at 600°C possess best ductility and high average n-value. 相似文献
20.
Transmission electron microscopy, quantitative optical microscopy, and texture studies were made on swaged and recrystallized
titanium wire of three impurity contents: zone refined, a special lot of intermediate purity, and commercial A-70. The electron
microscopy studies revealed that a) during recrystallization a number of processes overlap, and b) during grain growth there
occurs a decrease in the dislocation density within the grains along with the increase in the average grain size. The quantitative
microscopy studies indicated that the linear intercept grain size distribution is approximately log normal and that for a
given mean grain size the distribution is relatively independent of the combination of annealing time and temperature used
to obtain it. Moreover, there exists a range of grain sizes in space, the numbers of grains in each class interval changing
with increase in grain size. The so-called grain shape factor decreases with increase in mean grain size (annealing time)
at a constant temperature and with decrease in temperature for a constant grain size. The texture of the as-swaged wire and
the changes in the texture during grain growth are in qualitative accord with those previously reported for deformed and recrystallized
titanium. Impurity content influences the degree of these various structural characteristics but not their substance.
K. Okazaki, Formerly Visiting Research Associate, Metallurgical Engineering and Materials Science Department, University of
Kentucky, Lexington, Ky. 相似文献