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1.
采用电子背散射衍射技术对高硅钢近柱状晶初始组织直接热轧、温轧、冷轧和退火组织及织构演变进行分析,并测定相应退火板的磁性能.该实验条件下组织与织构演变规律体现了表层剪切细小组织和中心层粗大组织的竞争关系,其中中心层组织与原始立方取向相关或表现为α线取向.柱状晶的影响在最终退火组织中仍存在,少量立方取向区域可遗传到最终退火板中,虽然没有大量出现,仍有效削弱了{111}织构.形变退火过程中与原始立方取向线有关的晶粒尺寸普遍较大,有利于磁性.样品最终的磁感应强度低于文献报导的强{120}〈001〉或{100}〈021〉织构样品,但高于普通无取向高硅钢,且轧向和横向磁感应强度值差异小,所以柱状晶组织有利于无取向高硅钢的制备. 相似文献
2.
Ti-24Al-14Nb-3V-0.5Mo合金的压缩超塑性 总被引：2，自引：0，他引：2
对Ti24Al14Nb3V05Mo合金的超塑压缩变形行为进行了研究·结果表明,该合金的最佳超塑温度为980℃,最佳应变速率范围为(2×10-4～2×10-3)s-1·在超塑变形过程中,条状O相和α2相中发生了动态再结晶和等轴化过程;B2相中发生了动态回复·新形成的硬相等轴晶粒可在软的基体中滑动和转动,造成的应力集中由B2相中的位错运动松弛· 相似文献
3.
Isothermal hot compression tests of as-cast high-Cr ultra-super-critical (USC) rotor steel with columnar grains perpendicular to the compression direction were carried out in the temperature range from 950 to 1250°C at strain rates ranging from 0.001 to 1 s-1. The softening mechanism was dynamic recovery (DRV) at 950°C and the strain rate of 1 s-1, whereas it was dynamic recrystallization (DRX) under the other conditions. A modified constitutive equation based on the Arrhenius model with strain compensation reasonably predicted the flow stress under various deformation conditions, and the activation energy was calculated to be 643.92 kJ·mol-1. The critical stresses of dynamic recrystallization under different conditions were determined from the work-hardening rate (θ)–flow stress (σ) and -?θ/?σ–σ curves. The optimum processing parameters via analysis of the processing map and the softening mechanism were determined to be a deformation temperature range from 1100 to 1200°C and a strain-rate range from 0.001 to 0.08 s-1, with a power dissipation efficiency η greater than 31%. 相似文献
4.
用显微硬度方法在晶粒尺度范围内对多晶纯铝进行了晶内塑性变形,研究了退火前后压痕周边变形组织形貌。实验发现,仅在退火后的压痕周边出现了不同形态的滑移带,在滑移带的区域发现有大量位错露头并在某些局部范围内呈有序排列状态的现象,同时观察到滑移带直接穿越晶内偏聚区界的现象。文中分析了没有在晶内压痕周边区域内发现再结晶现象的原因,讨论了退火温度及时间、压下量及晶粒取向等因素对滑移带形成的影响。研究表明,与整体变形方式不同,晶内变形方法可以更方便地研究多晶材料塑性变形及再结晶时的一些组织特点。 相似文献
5.
多晶纯铝晶内局部变形组织分析 总被引：1，自引：0，他引：1
用显微硬度方法在晶粒尺度范围内对多晶纯铝进行了晶内塑性变形,研究了退火前后压痕周边变形组织形貌.实验发现,仅在退火后的压痕周边出现了不同形态的滑移带,在滑移带的区域发现有大量位错露头并在某些局部范围内呈有序排列状态的现象,同时观察到滑移带直接穿越晶内偏聚区界的现象.文中分析了没有在晶内压痕周边区域内发现再结晶现象的原因,讨论了退火温度及时间、压下量及晶粒取向等因素对滑移带形成的影响.研究表明,与整体变形方式不同,晶内变形方法可以更方便地研究多晶材料塑性变形及再结晶时的一些组织特点. 相似文献
6.
采用Gleeble-3800热模拟试验机研究Fe-36Ni合金在900~1200℃的热塑性行为,并用FactSage软件、扫描电镜及透射电镜等研究该合金热塑性的影响因素及作用机理.结果表明：合金中主要形成Al2 O3+Ti3 O5+MnS复合夹杂,夹杂物颗粒尺寸集中分布在0.5μm以下.合金热塑性在900~1050℃受晶界滑移及动态再结晶共同影响.晶界上分布的纳米级别(<200 nm)夹杂物有效钉扎晶界,抑制动态再结晶发生的同时减小晶界结合力.微米级别(>200 nm)夹杂物则促进显微裂纹在晶界滑移过程中的形成和扩展,损害合金热塑性.当温度高于1050℃时,较高的变形温度使再结晶驱动力大于钉扎作用力,合金发生动态再结晶,有效提高热塑性.在1100~1200℃区间内,枝晶间裂纹的形成、晶界滑移的加剧及动态再结晶晶粒尺寸增大都降低合金热塑性. 相似文献
7.
对CGO取向硅钢二次再结晶中断实验进行了研究,发现二次再结晶升温过程中,仅在异常长大开始前,高斯晶粒尺寸明显大于其他晶粒,且不同取向晶粒的数量与脱碳退火时的特征一致.高斯晶粒晶界上MnS等抑制剂的优先粗化使高斯晶粒能够率先发生异常长大,且只有晶界弯曲严重或经过很小的生长几个晶粒就能合并的高斯晶粒才能成为二次晶核.在高斯晶粒异常长大过程中,晶界形貌参差不齐,呈岛屿状.研究表明:高斯晶粒独特的生长方式,可能是使二次再结晶能很快完成的原因. 相似文献
8.
1420铝锂合金的温压变形及动态再结晶行为 总被引：2，自引：4，他引：2
采用金相、扫描电镜及背反射电子衍射等检测手段,对1420铝锂合金在温压变形时不同变形量的微观组织与织构进行研究。结果表明:在350℃及较高的应变速率.ε=6.93 s-1的变形条件下,1420铝锂合金在变形量为90%时出现粒径d<5μm的大量细晶组织,发生了动态再结晶;立方取向晶粒的形核与长大均不占优势,再结晶晶粒表现为强烈的形变取向。为此,提出了一种新的粒子激发形核与亚晶倾转形核长大的混合再结晶模式。 相似文献
9.
将热-力耦合弹塑性有限元方法与微观组织演化模型相集成,定量比较了恒定平均应变速率和恒定压头速率2种压下模式对镁合金AZ31B高温变形和微观组织演变的影响.采用AZ31B镁合金圆柱形试样进行Gleeble热力模拟试验获得有限元模拟所需的高温流动应力曲线与再结晶晶粒尺寸实测数据,并通过二次开发与有限元模型相集成.研究结果表明,由于端面摩擦的存在,2种压下模式下变形场和微观组织场都呈现不均匀分布特性.与恒定平均应变速率相比,恒定压头速率压下时晶粒尺寸均值减小,均方差略有增加. 相似文献
10.
Q235碳素钢不同热变形条件下退火过程的织构分析 总被引：1，自引：0，他引：1
利用扫描电镜、背散射电子衍射(EBXD)和X射线衍射技术研究了三种方式热变形后保温时铁素体的长大行为.结果表明,回复、再结晶和长大的相对程度与第二相粒子的状态及铁素体的取向分布有关.形变强化相变产生的超细铁素体中形变储存能较低,退火时难以发生静态再结晶,而以晶粒长大为主,铁素体因第二相出现较晚而充分生长:A1温度以下纯铁素体区形变的铁素体虽然形变储存能最高,形变量最大,但第二相钉扎最明显,铁素体仅发生部分再结晶,<111>取向形变晶粒比<100>取向形变晶粒更明显地被削弱;α+γ两相区形变时,铁素体(亚)晶粒发生回复式长大,<111>取向晶粒和<100>取向晶粒有不同的再结晶倾向. 相似文献
11.
The effect of the microstructure of an Al 7050-T7451 substrate on the anodic oxide formation in sulfuric acid was studied in this article. The microstructure of the substrate was assessed by optical microscope (OM) and transmission electron microscope (TEM). The surface and cross-section morphologies of the oxide films were examined by scanning electron microscope (SEM). The chemical composition of intermetallic particles in the alloys and films was investigated using energy dispersive spectroscope (EDS). The roles of intermetallic phases and grain or subgrain boundaries on the oxide film formation were researched using the potentiodynamic and potentiostatic polarization technique in sulfuric acid solution. The results show that the transition of coarse intermetallic particles or grain (subgrain) boundaries at the surface of Al alloys can be characterized by potentiodynamic polarization curves. The surface and cross-section micrographs of the anodic layer seem to preserve the microstructure of the substrate. Large cavities in the anodic films are caused by the preferential dissolution of coarse AItCuMg particles and the entrance of Cu-rich remnants into the electrolyte during anodizing. The Al7Cu2Fe particles tend to be occluded in the oxide layer or lose from the oxide surface because of peripheral trenching. Small pores in the films are induced by the dissolution of precipitates in grain or subgrain boundaries. The film surface of recrystallized grain bodies is smooth and homogeneous. 相似文献
12.
22CrS齿轮钢变形奥氏体动态再结晶行为及组织演变 总被引：1，自引：0，他引：1
采用Gleeble1500热模拟试验机研究了一种新型Mn Cr系齿轮钢在变形量为70%,变形速率为0.1～1s-1,变形温度为850～1150℃,原始奥氏体晶粒尺寸为70～150μm条件下的动态再结晶行为及再结晶后奥氏体晶粒尺寸的变化规律·研究结果表明:在一定的变形量下,变形速率、变形温度、奥氏体晶粒尺寸是影响再结晶的3个因素,只有变形条件Z小于上临界值Zc时才会发生动态再结晶·再结晶后奥氏体晶粒尺寸 D是由变形条件Z惟一地决定而与原始奥氏体晶粒大小无关,Z增加, D减小,二者符合关系式Z=A D-3.91· 相似文献
13.
本文研究了热变形参数对50CrV 钢静态再结晶行为的影响,引用了 Y 参数(Yao Parameter)使热变形奥氏体静态再结晶图大为简化.本实验再一次指出:Y 参数不仅在18Ni 马氏体时效钢中具有实用性,而在50CrV 钢中验证了 Y 参数也同样具有实用性. 相似文献
14.
The effect of aging treatment on the superelasticity and martensitic transformation critical stress in columnar-grained Cu71Al18Mn11 shape memory alloy (SMA) at the temperature ranging from 250°C to 400°C was investigated. The microstructure evolution during the aging treatment was characterized by optical microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The results show that the plate-like bainite precipitates distribute homogeneously within austenitic grains and at grain boundaries. The volume fraction of bainite increases with the increase in aging temperature and aging time, which substantially improves the martensitic transformation critical stress of the alloy, whereas the bainite only slightly affects the superelasticity. This behavior is attributed to a coherent relationship between the bainite and the austenite, as well as to the bainite and the martensite exhibiting the same crystal structure. The variations of the martensitic transformation critical stress and the superelasticity of columnar-grained Cu71Al18Mn11 SMA with aging temperature and aging time are described by the Austin–Rickett equation, where the activation energy of bainite precipitation is 77.2 kJ·mol?1. Finally, a columnar-grained Cu71Al18Mn11 SMA with both excellent superelasticity (5%–9%) and high martensitic transformation critical stress (443–677 MPa) is obtained through the application of the appropriate aging treatments. 相似文献
15.
不同形变速率条件下低碳钢过冷奥氏体形变过程铁素体超细化 总被引：6，自引：1，他引：6
研究了低碳钢过冷奥氏体在760℃,形变速率为1 s-1和10 s-1变形时组织演变规律.结果表明,形变速率为1 s-1时真应力-应变曲线双峰特征为形变强化相变和铁素体动态再结晶的表征,相变形核集中在铁素体/奥氏体相界前沿奥氏体高畸变区,晶粒长大在时间和空间上受到限制,细化能力较高;形变速率提高到10 s-1时,相变动力学提前,曲线只表现为形变强化相变的单峰特征,相变形核除了在上述铁素体/奥氏体相界前沿奥氏体高畸变区,还分布到奥氏体晶内各处,晶粒间约束有所减小,尺寸稍大.通过形变强化相变和铁素体动态再结晶可以获得平均晶粒尺寸为(1.98士1.07)μm和(2.33士1.01)μm(10 s-1)左右的微细铁素体晶粒. 相似文献
16.
热变形造成的奥氏体组织结构的变化将影响到热变形奥氏体在随后冷却过程中的相变．依据热模拟试验结果，研究了变形温度、变形速率、变形量和变形后高温停留影响相变过程的微观物理本质，认为变形促进热变形奥氏体的相变，提出变形温度、变形速率和变形后高温停留时间对热变形奥氏体转变过程没有直接联系，但可以通过对再结晶过程的控制影响相变过程．再结晶虽然可能细化了晶粒，但大量消耗了热变形奥氏体中的晶体缺陷，其结果是迟滞了相变过程． 相似文献
17.
异步轧制对AZ31镁合金静态再结晶及晶粒细化的影响 总被引：1，自引：1，他引：1
研究了AZ31镁合金薄板在异步轧制过程中,异速比、压下率及退火工艺对其退火晶粒尺寸的影响.结果表明:适当提高轧制异速比和道次压下率能够显著细化晶粒,但是异速比过高时,轧辊与轧件会产生相对滑动,细化晶粒效果降低,其中异速比为1.3时,细化晶粒效果最佳;剪切作用使镁合金中孪晶数量及分布均匀程度提高,位错缠结被"切碎",畸变能得以更均匀地分布于变形体内,是异步轧制具有良好晶粒细化效果的主要原因;此外,合理的异步轧制工艺还能缩短镁合金板带所需的中间退火和成品退火时间. 相似文献
18.
针对某高线车间的生产实际，对82B钢在热轧过程中的组织演变规律进行分析，预测了其晶粒尺寸的大小。在变形温度为900～1050℃、应变速率为0．1—25s^-1、单道次压下的实验条件下，研究了不同参数对临界应变的影响。 相似文献
19.
The effect of dislocation structure evolution on low-angle grain boundary formation in 7050 aluminum alloy during aging was studied by using optical microscopy, transmission electron microscopy, and electron backscatter diffraction analysis of misorientation angle distribution, cumulative misorientation and geometrically necessary dislocation (GND) density. Experimental results indicate that coarse spindle-shaped grains with the dimension of 200 μm×80 μm separate into fine equiaxed grains of 20 μm in size as a result of newborn low-angle grain boundaries formed during the aging process. More specifically, the dislocation arrays, which are rearranged and formed due to scattered dislocations during earlier quenching, transform into low-angle grain boundaries with aging time. The relative frequency of 3°-5° low-angle grain boundaries increases to over 30%. The GND density, which describes low-angle grain boundaries with the misorientation angle under 3°, tends to decrease during initial aging. The inhomogeneous distribution of GNDs is affected by grain orientation. A decrease in GND density mainly occurs from 1.83×1013 to 4.40×1011 m-2 in grains with 〈111〉 fiber texture. This is consistent with a decrease of unit cumulative misorientation. Precipitation on grain boundaries and the formation of a precipitation free zone (PFZ) are facilitated due to the eroding activity of the Graff etchant. Consequently, low-angle grain boundaries could be readily viewed by optical microscopy due to an increase in their electric potential difference. 相似文献
20.
采用Gleeble 1500型热模拟试验机进行单轴压缩实验,研究了Fe3Al基合金在温度为850 ℃、应变速率为10-3 s-1条件下的组织演变. 结果表明:在本实验变形条件下,Fe3Al基合金能够发生动态再结晶. 变形初期,Fe3Al可以通过晶界弓弯机制形成动态再结晶核心,即发生了不连续动态再结晶现象,但再结晶核心不易长大. 随着应变量的增加,通过连续动态再结晶形成一定量的再结晶细小晶粒. 相似文献