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为了提高7075铝合金的力学性能,7075铝合金在350℃无润滑条件下进行了5道次的累积叠轧焊实验,通过X射线衍射(XRD)与透射电镜(TEM)分析,研究了7075铝合金在叠轧过程中微观组织的演化规律,利用室温拉伸实验,研究了叠轧道次对7075铝合金力学性能的影响规律,并且采用扫描电镜(SEM)对拉伸断口形貌进行了分析。结果表明:7075铝合金在叠轧过程中材料的组成相η相发生回溶,数量减少;微观组织经历由位错缠结/位错胞状结构向形变亚晶结构转变的过程,5道次后,形成了尺寸小于1μm的亚晶组织;材料的强度随道次的增加而增加,5道次后,其抗拉强度与屈服强度分别达到373.52,315.84 MPa,约为原始合金的1.8倍和3.2倍,同时,延伸率则随着叠轧道次的增加而下降,5道次后,延伸率仅为原始合金的1/3,并且拉伸断裂由韧性断裂转变为脆性断裂。 相似文献
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在室温条件下对1060工业纯铝进行7道次的累积叠轧焊轧制,将综合力学性能较好的ARB道次试样进行热处理实验研究,分析经过ARB剧烈塑性变形的金属材料在热处理条件下其微观组织与力学性能的变化。实验结果表明,ARB 5道次材料的综合力学性能较好,其抗拉强度为210 MPa,延伸率为9.3%。ARB 5道次试样在200℃以下温度条件下进行热处理,其拉伸性能稳定,显微组织处于回复阶段,超细晶材料组织和性能具有良好的稳定性。 相似文献
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陈锁泉 《有色金属材料与工程》1982,(4)
利用x射线衍射原理测定材料的极图和反极图来描述和分析材料织构的方法,早为人们所熟知。所谓极图就是在试样座标系O—ABC中(OA、OB、OC分别表示板材的轧向、横向、轧面)试样每个晶粒i晶面法线的极点密度在平面的投影。反之,反极图就是在晶体座标系 相似文献
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以Mg-Gd-Y-Zn-Zr挤压态合金为材料,采用同步轧制(SR)和异步轧制(DSR)工艺,通过光学显微镜(OM)、电子背散射衍射(EBSD)、 X射线衍射(XRD)宏观织构检测以及室温拉伸等手段研究了两种轧制方式下板材微观组织的演变、织构组态及力学性能。结果表明:经SR和DSR轧制后,大尺寸的变形组织由于剪切破碎作用被细小的再结晶组织取代,两种轧板表层组织都比中心层组织更加细小均匀;与SR轧板相比,DSR轧板残留的变形区组织很少,动态再结晶程度更高,组织更加均匀;由EBSD分析结果可知,SR和DSR板材的再结晶机制均为连续动态再结晶;SR板材内部存在大量的低角度晶界(67.8%),仍然存在15μm以上的大晶粒,动态再结晶程度不高;DSR板材低角度晶界比例大大降低(25.8%),晶粒尺寸分布均匀,动态再结晶程度较高;SR板材呈现基底织构的特征,织构强度达到13.9; DSR板材基极向横向(TD)和轧向(RD)呈现均匀发散状态,织构强度降低到4.8;相同轧制条件下,DSR板材的抗拉强度和屈服强度分别比SR板材高30.1 MPa和38.2 MPa, DSR板材的延伸率(8.7%)比SR板材... 相似文献
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等径弯曲通道变形对超低碳钢组织及性能的影响 总被引:1,自引:0,他引:1
研究了室温下C方式等径弯曲通道变形(ECAP)对超低碳钢组织及性能的影响。结果表明:第1道次ECAP变形后,组织细化效果最显著;随变形道次的增加,组织由取向差小的板条状亚晶演变成取向差大的等轴晶;第4道次ECAP变形后,晶粒平均尺寸约03 μm;变形道次继续增加,晶粒尺寸变化不显著,而晶粒取向差不断增大。这表明第4道次ECAP变形为超低碳钢细化极限;ECAP变形可大幅度提高超低碳钢的强度,并保持较高的塑性。 相似文献
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累积叠轧焊制备超细晶IF钢微观组织与力学性能 总被引:8,自引:0,他引:8
采用累积叠轧焊方法制备了超细晶IF钢,对其微观组织和力学性能进行了分析。实验结果表明,累积叠轧后IF钢的平均晶粒尺寸为700nm;抗拉强度为621.3MPa,达到冷轧IF钢抗拉强度的2.02倍,屈强比σ0.2/σb为0.81。在累积叠轧过程中产生的氧化物夹杂导致超细晶IF钢的脆化。 相似文献
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Lihong Su Cheng Lu Guanyu Deng Kiet Tieu 《Metallurgical and Materials Transactions B》2014,45(2):515-522
The AA5005/AA6061 laminated composite has been fabricated by the accumulative roll bonding (ARB) using commercial AA5005 and AA6061. In the ARB process, one piece of AA5005 sheet and one piece of AA6061 sheet were stacked together and rolled with a 50 pct reduction without any lubrication. The materials were heated at 473 K (200 °C) for 10 minutes before each rolling process and were deformed up to four cycles to accumulate an equivalent strain of 3.2 and form an AA5005/AA6061 laminated composite. Mechanical properties and microstructure of the laminated composites were tested. The hardness and tensile strength increased, and the grain size reduced with the number of ARB cycles. Ultrafine grains elongated along the rolling direction were developed during the ARB process. The thicknesses of the grains of both the AA5005 and AA6061 layers were less than 200 nm after the fourth cycle. The uniform elongation decreased drastically after the first cycle ARB and stayed almost unchanged after further ARB process. The hardness of the AA5005 layer was slightly lower than that of the AA6061 layer. The microstructures from optical microscope and transmission microscope showed that in the AA6061 layer large precipitates in the micron scale and small particles less than 100 nm were present, whereas in the AA5005 layer there were large scale precipitates, but no small-sized particles. 相似文献
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《钢铁冶炼》2013,40(3):249-255
AbstractA number of empirical equations, based primarily on average metallographic grain size and carbide thickness, exist to predict the Charpy impact transition temperature in steels. Some of these commonly used equations, successful for normalised steels, have been shown in this paper to be inadequate for predicting the transition temperature for thermomechanically control rolled (TMCR) microalloyed steels. Thermomechanical control rolling can produce clusters of small grains with low angle grain boundaries, i.e., the steel shows mesotexture. The cleavage facet size in TMCR steels has been found to be significantly larger than the optical grain size and it was also observed that individual cleavage facets can be comprised of multiple grains. In contrast, it was observed for a heat treated steel that the facet size matches the optical grain size and that individual facets consist of single grains. It is concluded that in TMCR steels, the average microstructural unit experienced by the crack front is larger than the optical grain size because mesotexture causes groups of closely orientated grains to be treated as single 'effective' grains. This paper shows that the 50% and 27 J impact transition temperatures can be predicted for TMCR steels using the existing equations if mesotexture and grain boundary carbide size are taken into account. 相似文献
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Columnar grains in cast slabs of electrical steel show strong anisotropy in grain orientation and morphology and thus influence the subsequent microstructure and texture after hot rolling significantly. The texture evolution of hot rolled sheets containing initial columnar grains with their <100> directions approximately parallel to the rolling direction (RD), transverse direction (TD) and normal direction (ND) of the hot rolled sheets was investigated by using EBSD technique. The results indicated that, whatever the initial texture of the columnar grains was, typical Goss, brass-type and copper-type shear texture component could develop in shear-deformed surface region. The copper-type texture formed under the maximum shearing force with the fine, sheared or dynamically recrystallized grains, and Goss grains were mainly elongated and deformed grains, while brass grains behaved between them. Additionally, the rotating relationship of the three types of shear textures was different due to the restriction of grain boundaries. In homogenously deformed center region, the RD sample contained more {112} <110> grains, and TD sample was covered by {100} textures such as {100}<011> and {100}<021> with coarse grains, while the ND sample developed many {100}<011> grains which were attributed to more {100} grains in the initial sample. Remarkable texture transition occurred on both sides of grain boundaries when {110} grains were adjacent to α-fiber texture grains. It was found that significant texture gradient and preferred distribution of rotating axis existed in the soft orientation grains on the α-fiber when the grains neighbored hard grains on γ-fiber. 相似文献
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Growth Process of Goss Grains during Secondary Recrystallization of Grain‐oriented Electrical Steels
The coarsening behaviour of Goss grains in grain oriented electrical steel during annealing after cold rolling was investigated. The results show that the coarsening resistance of fine second phase particles was reduced inside the surface grains. This induced particle coarsening and the reduction of particle density. The reduction of particle density was grain orientation dependent because of the elastic anisotropy of ferrite. Experimental results also revealed that some small surface Goss grains exhibited higher particle density than their neighbouring grains. This may account for the higher coarsening resistance of fine particles and be responsible for the stronger pinning effect on the migration of grain boundaries. Therefore, these Goss grains may have grown at the expense of smaller neighbouring grains and most were very unlikely to be consumed by large neighbouring grains during secondary recrystallization annealing. When their sizes became even larger, they consumed the large grains in turn and consequently formed a strong Goss texture. 相似文献
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The structure and texture formation for single cold rolling (SCR) with annealing and double cold rolling (DCR) with annealing were investigated based on optical microscope and X-ray diffraction (XRD) with a Nb+Ti bearing interstitial free (IF) steel. The results indicated that DCR recrystallization grain was smaller than that of SCR sample and double cold rolling process resulted in better mechanical properties than those resulted from single cold rolling process with the same total reduction conducted. The plastic strain ratio increases from 2. 23 for single cold rolling process to 3. 2 for double rolling process. The fish-bone structure was observed in all SCR and DCR samples. DCR annealed sample is made up of equiaxed grains of almost uniform size, whereas SCR annealed sample shows a duplex grain structure, consisting of both large and small-sized grains. (Ti+Nb)C and Fe(Ti+Nb)P type precipitates were very rarely observed in SCR annealed and DCR annealed steels. The intensity of {111}∥ND for the DCR annealing was higher than that for SCR annealing. 相似文献
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6063 Al alloys was cryorolled under solutionized (sample1) and peak aged condition (sample2) to study the role of dynamic precipitation on the strengthening mechanism. It is observed that in case of sample1 dislocations density is more compare to sample2. In the 1st case high angle sub grains (presence of high fraction of HAGBs) of less than 100 nm in size have been generated during cryorolling. In case of sample2, grains are aligned along the rolling direction. This is obvious that the higher densities of dislocations (in sample1) restrict the grain boundaries to be aligned along the rolling direction. Therefore, the grain boundaries are aligned along the rolling direction only in case of sample2. Whereas such type of alignments of grain boundaries are not observed in case of sample1. Presence of very fine grains along with high density of dislocations are responsible for attaining higher strength of sample1 compare to sample2. 相似文献