累积叠轧焊对退火态纯铝的显微组织和力学性能的研究

采用累积叠轧焊的方法对退火态的1060纯铝进行了累积叠轧实验，研究了累积叠轧次数对金属材料抗拉强度、延伸率、显微硬度、塑性的影响规律，通过透射电镜、拉伸及显微硬度实验分析了规律形成的原因。结果表明：经过多道次的轧制实验后，晶粒尺寸急剧细化，7道次后超细晶增多，晶粒最小细化到500nm。材料的抗拉强度和显微硬度也有显著提高。     

CSP线热轧薄板的组织演变及微观取向研究

利用背电子散射衍射（EBSD）技术，研究了3种不同厚度规格的低碳钢CSP热轧薄板的组织演变和微观取向，实验结果表明：热轧终轧组织为再结晶奥氏体和变形奥氏体的混合体；相变后的铁素体晶粒中含有亚晶和位错，导致板带的强度升高而伸长率下降。板带的最终组织中含有残留的热轧织构，织构组分较杂且弱。最终组织中的铁素体晶粒尺寸不均匀，由EBSD系统按邻域面积确定的铁素体晶粒尺寸比按形貌确定的铁素体晶粒尺寸小。     

热处理对ARB1060纯铝组织与性能的影响

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...     

7075铝合金累积叠轧焊组织与性能

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。     

TC4包复叠轧薄板组织与性能特征

对TC4薄板包复叠轧及单片轧制工艺生产板材取样分析，研究了包复叠轧产品性能、显微组织、极图、ODF织构等的特征，数据表明包复叠轧产品具有组织和性能各向异性小，塑性好，利于超塑成形的特点。     

多晶材料织构的又一表示法——三维取向分布函数(ODF)分析法

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     

一种表面纳米化的大规格超细晶钛合金薄板及其制备方法

本发明公开了一种表面纳米化的大规格超细晶钛合金薄板及其制备方法,包括初步轧制、包覆叠轧和表面处理。该方法通过初始大变形轧制及后续低温包覆叠轧工艺得到晶粒尺寸小于2μm的大规格超细晶钛合金薄板;且随着碾压道次数的增加,下压力逐渐增加,经过多道次碾轧后可获得表面为纳米晶、芯部为超细晶的钛合金薄板。     

异步轧制对Mg-Gd-Y-Zn-Zr板材组织、织构和性能的影响

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...     

等径弯曲通道变形对超低碳钢组织及性能的影响

 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03 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。     

累积叠轧焊制备超细晶IF钢微观组织与力学性能

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。     

Microstructure and Mechanical Properties of AA5005/AA6061 Laminated Composite Processed by Accumulative Roll Bonding

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.     

Predictability of Charpy impact toughness in thermomechanically control rolled (TMCR) microalloyed steels

Abstract

A 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.     

Texture Evolution of Columnar Grains in Electrical Steel During Hot Rolling

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.     

低温轧制提高65Mn盘条塑韧性能机理分析

 通过常规工艺、低温开轧、低温精轧3种试验工艺研究了低温轧制对提高65Mn塑韧性能的影响,利用金相显微镜OM、扫描电镜SEM、EBSD等分析了3种试验工艺的组织、大小角度晶界、晶粒尺寸以及片层间距,研究结果表明,低温工艺显著提高弹簧钢的面缩率,降低同圈波动;大小角度晶界、细化的原始奥氏体晶粒与珠光体球团、片层间距是弹簧钢塑韧性能提高的关键所在。     

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.     

Structure and Texture Formation During Single and Double Cold Rolling and Annealing Processes for Nb+Ti Added Interstitial-Free Steels

 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.     

MnS在固态低硫钢中析出的实验室研究

采用高温激光共聚焦显微镜对低硫钢试样抛光表面的MnS夹杂物析出进行了观察,利用高温激光共聚焦观察结果进行了控温轧制M nS析出试验,用SEM-EDS和ASPEX分析了析出物的成分.结果表明,MnS在表面的首次析出发生在1067℃并伴随有表面变形,在859.7℃当界面能随表面变形释放后停止,MnS的第二次析出发生在790...     

高线轧机特高轧制速度下轧件变形行为研究

用纯铁作为试验原料,进行了特高轧速的生产试验,结果表明原料某部位晶粒大,轧后对应部位晶粒也大, 某部位晶粒小,则轧后对应部位晶粒也小,在精轧机出口速度为100 m/s、变形速率相当于2 880 s -1 的条件下,轧件 并未仅产生表面变形,轧件的变形也已渗透到轧件的中心。坯料晶粒均匀,轧后轧件的晶粒也均匀。但从轧件纵 截面的晶粒形状看,轧件中心晶粒沿纵向稍有伸长,表面晶粒沿纵向稍有压缩,这是由于孔型轧制的特殊性造 成的。     

Role of dynamic precipitation on the strengthening mechanism of cryorolled 6063 Al alloy

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 1^st 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.