退火温度对异步轧制铜/铝复合带材组织与性能的影响

采用异步轧制工艺进行了铜/铝薄带的复合,并对复合带材进行了退火处理。利用金相显微镜、扫描电镜和拉伸试验机进行了复合带组织的观察和性能的测定。结果表明,复合带材的退火温度与其剥离强度呈抛物线关系,复合带材剥离强度在300℃保温1 h达到最大值。退火温度升高,促进界面元素扩散,界面化合物层变厚,伸长率增加,但温度过高会导致界面开裂。     

异步轧制铜/铝复合板界面结合强度研究

对不同异步速比条件下铜/铝复合板界面结合强度和剥离形貌进行了研究,分析了轧制变形区界面正应力、剪切应力以及等效应变对复合板结合强度的影响机制。结果表明:随异步速比的增加,铜/铝复合板界面的剥离强度先增大后减小,且在异步速比为1. 15时达到最大值34. 2 N·mm-1。从剥离形貌来看,异步速比为1. 15时复合板剥离界面上黏着的铝脊数量和面积达到最大,且异步速比大于1. 15时,剥离面黏着的铝屑明显增加。模拟结果分析发现:随着异步速比的增加,界面处的等效应变和剪切应力均逐渐增大,可有效促进金属间的结合效果。当异步速比大于1. 15时,轧制变形区出口侧的剪切应力急剧上升,对结合界面造成一定的破坏作用,因此复合板的剥离强度随异步速比的增加,呈先上升后迅速下降的变化趋势。     

铜/铝/铜复合板异步轧制变形行为有限元分析

采用ANSYS/LS-DYNA软件建立了铜/铝/铜复合板异步轧制成形弹塑性有限元模型,将有限元模型仿真结果同实际轧制实验结果进行对比,证明有限元模型的准确性。通过对异步轧制变形区进行分析和研究发现,在相同条件下,与同步轧制相比,异步轧制可以有效地减小轧制正应力,并增大后滑区摩擦应力;异步轧制搓轧区可以促进复合板结合界面的金属流动,在其他轧制条件相同的情况下,压下率越大,搓轧区越小,异步速比越大,搓轧区越大;靠近快速辊一侧结合界面铜板的等效应变要大于靠近慢速辊一侧结合界面铜板的等效应变,中间铝板的等效应变大于两侧铜板。随着异步速比的增大,复合板结合界面上两种金属的等效应变的差距逐渐缩小,变形将会更加协调,有利于增强复合板的结合强度。整体研究对铜铝复合板制备工艺的优化提供了理论依据。     

冷轧铜铝复合板结合界面残余应力分析

针对冷轧铜铝双层板金属的变形特征以及各轧制工艺下界面残余应力的分布情况,采用有限元计算方法,分别将轧制速度、异径同步、异径异步各工艺产生的界面残余应力进行分析。研究结果表明,冷轧铜铝双层板的复合变形过程可分为4部分;铜板复合面的应变直接影响复合效果;异径同步轧制铜铝复合板时,随着辊径比的增大,铜板复合面的总变形量增大,当辊径比大于1．6时,总变形的增量不明显,辊径比取1．4~1．6时,残余应力较小;异径异步轧制铜铝复合板时,随着辊径比的增大,铜板复合面的总变形量增大,轧制速比取1．2~1．4时,残余应力较小。     

冷轧铜铝复合板结合界面速度场分析（英文）

通过有限(FEM)元速度场研究了冷轧铜铝双层板的复合过程,将该过程中金属的变形特征进行了分析,同时,将有限元计算结果与某工厂数据相结合,分析了轧制速度、压下率、异径同步、异径异步对铜铝双层板复合的影响。结果表明,速度场模型能够更有效地说明铜铝板的复合过程;轧制速度越大,变形区出口处复合面金属流动的同步性越差,复合强度越低;异径同步轧制铜铝复合板时,辊径比取1.4~1.6,变形区出口处复合面金属流动的同步性越好,复合强度较高;异径异步轧制铜铝复合板时,轧制速比取1.2,变形区出口处复合面金属流动的同步性越好,复合强度较高。     

冷轧铜铝复合板结合界面速度场分析

文章通过有限元速度场研究了冷轧铜铝双层板的复合过程,将该过程中金属的变形特征进行了分析,同时,将有限元计算结果与某工厂数据相结合,分析了轧制速度、压下率、异径同步、异径异步对铜铝双层板复合的影响。研究表明,速度场模型能够更有效地说明铜铝板的复合过程;轧制速度越大,变形区出口处复合面金属流动的同步性越差,复合强度越低;压下率越大, 变形区出口处复合面金属流动的同步性越强,复合强度越高;异径同步轧制铜铝复合板时,辊径比取1.4~1.6,变形区出口处复合面金属流动的同步性越较好,复合强度较高;异径异步轧制铜铝复合板时,轧制速比取1.2,变形区出口处复合面金属流动的同步性越较好,复合强度较高。     

Al/Al板复合轧制中界面焊合与分离

对退火态Al/Al板在室温下进行同步和异步复合轧制实验,发现同步轧制后的Al/Al板界面发生焊合,而异步轧制使已焊合的Al/Al板界面又出现分离。为了进一步验证Al/Al板界面焊合与分离现象,分别对同步和异步轧制后的试样进行拉伸实验,并观察拉伸断口的SEM像。分析认为:同步轧制时轧件表面受到的纵向剪应力最大,而轧件厚度二分之一处(对称面)的纵向剪切应力为0,这种剪应力分布有利于复合界面在强大压应力下实现焊合;相比之下,异步轧制存在搓轧区,搓轧区中的纵向剪应力沿轧件厚度方向分布均匀,即Al/Al结合界面受到的纵向剪应力与轧件表面处几乎相等,此剪应力对已经焊合的界面产生破坏作用,导致焊合面发生剪切分离。为了深入探究同步轧制焊合与异步轧制分离的机制,采用有限元方法进行模拟,得到异步轧制下Al/Al界面处纵向剪应力为57.8 MPa,达到工业纯铝复合界面的剪切强度,足以引起焊合面的剪切分离。这为诠释异步轧制下的界面分离现象提供了佐证,这些研究结果对层状金属复合轧制方式的选择具有较大的参考价值。     

退火温度对异步轧制铜/铝复合板界面组织及力学性能的影响

研究退火温度对异步轧制法制备的铜/铝复合板界面组织及力学性能的影响,采用SEM观察界面组织形貌,结合EDX、XRD分析界面物相成分,采用显微硬度和室温拉伸实验表征复合板的力学性能。结果表明,异步轧制法制备的铜/铝复合板界面形变储能较高,退火温度为400℃时界面扩散明显;随着退火温度的升高,复合界面先后生成金属间化合物CuAl2、Cu9Al4、CuAl相,界面撕裂位置位于金属间化合物之间;界面层的显微硬度比基体的高,这是因为受到硬脆性化合物和高温软化的共同影响;退火温度越高,复合板抗拉强度越低,断裂伸长率越大。研究表明,异步轧制法制备的铜/铝复合板最佳退火温度为400℃。     

铜/铝冷轧复合薄带热处理工艺及界面组织和性能研究

利用万能材料试验机、金相显微镜、X射线衍射仪和电子探针等仪器,研究了铜/铝/铜冷轧三层复合薄带的热处理工艺对薄带的界面组织和性能的影响。结果表明,随退火温度升高或保温时间的延长,复合带强度降低,塑性增强;退火后复合带界面宽度为1.5~6.5μm,410℃/10 min退火时复合带有最佳的力学性能;界面共有3层结构,有5种脆性化合物相生成,分别是Cu9Al4、Cu4Al3、Cu3Al2、CuAl、CuAl2等,其尺寸数量级为10-4~10-8mm2;在形态上,Cu9Al4、Cu4Al3、Cu3Al2呈多边形块状,内有许多平行板条,CuAl2相呈椭圆状,CuAl呈弥散颗粒状。     

冷轧铜-铝复合带翘曲变形研究

铜-铝复合带是将铜带复合在铝带上随后冷轧而成,但冷轧过程中复合带会发生翘曲。借助于MSC. MARC有限元软件建立了冷轧铜-铝复合带的二维模型,研究了道次压下率、铜带与铝带的厚度比和轧制速率对冷轧铜-铝复合带翘曲程度的影响。采用二辊冷轧机进行了铜-铝复合带的冷轧试验,并与有限元模拟结果进行了对比。结果表明:采用厚度比为1∶4的铜带和铝带,以175 mm/s的速率冷轧的铜-铝复合带,随着道次压下率从55%增大至70%,其曲率先减小后增大,以57.5%的道次压下率冷轧的复合带平直度最好。以60%的道次压下率和175 mm/s的速率冷轧的复合带,其曲率随着铜带与铝带厚度比的增加而减小。采用厚度比为1∶6的铜带和铝带,以70%的道次压下率和125～225 mm/s的速率冷轧的复合带,其曲率先减小后增大,以180 mm/s的速率冷轧的复合带平直度最好。     

Effects of processing parameters on the bond strength of Cu/Cu roll-bonded strips

Roll bonding, widely used in manufacturing large layered composite sheets, is a solid phase method for bonding similar or dissimilar metals by rolling. In this study, the effects of process parameters such as rolling reduction, rolling temperature, rolling speed, initial thickness of strip, and surface roughness on the bond strength between two-layer strips of Cu/Cu were investigated. The strips were subjected to chemical and mechanical cleaning prior to rolling, and after rolling, bond strengths were measured using the peeling test. It was observed that increased reduction, rolling temperature, strip width, and surface roughness led to an increase in peeling strength while increased rolling speed and initial thickness of strips caused peeling strength to decrease. Results also showed that increasing the initial thickness of strips would increase threshold deformation.     

异步热轧对钛合金Ti-6Al-4V微观组织及力学性能的影响

通过异步/同步热轧实验研究了异步热轧工艺对钛合金显微组织和力学性能的影响。实验表征了试样的显微组织、力学性能、断口形貌和微观取向。实验结果表明,复杂应变路径较之简单应变路径能更好的细化晶粒及同时提高强度和塑性,并且表层晶粒小于中心晶粒。异步轧制工艺相比同步轧制能更好获得细小晶粒。异步轧制试样的强度及塑性值高于同步轧制试样相应值,提高异步速比可提高强度及塑性值。异步轧制试样的塑性变形机制可能是滑移,而同步轧制试样塑性变形机制为滑移或孪晶。     

Shear deformation and grain refinement in pure Al by asymmetric rolling

Asymmetric rolling（ASR）, as one of severe plastic deformation（SPD） methods, was widely used to make ultra-fined materials with enhanced performance. Internal marks were used to show the shear deformation during asymmetric rolling with pure aluminium as a model material. Effects of reduction ratio and mismatch ratio on the shear deformation were studied. With the observed shear deformation results, equivalent strain was calculated. For lager shear deformation, rolling equipment was modified to increase friction between specimen and the rollers. Consequently, extremely fine grains with size of 500 nm are obtained in pure aluminium. With improved asymmetric rolling, the ability of grain refinement of ASR is greatly improved.     

异速异步轧制翼缘板钢晶粒的变化特征

采用异速异步轧制技术,对翼缘板钢分别进行累计九道次冷轧,用光学显微镜、电子扫描显微镜观察轧件的显微组织。结果表明:在相同的压下量下,随着异速比增大,晶粒长度和高度的比值也增大,用晶粒长高比值可以在一定程度上反映异步轧制对轧件所受附加剪切变形影响关系。对冷轧后的轧件进行了拉伸和退火实验,结果表明:随着异速比增大,抗拉强度增加,晶粒平均直径变小,异步轧制与同步轧制相比应变储能更高,可以产生更多的位错和亚晶。     

The bonding properties and interfacial morphologies of clad plate prepared by multiple passes hot rolling in a protective atmosphere

SUS304 stainless steel and plain carbon steel were first bonded by hot rolling in an argon atmosphere and were subsequently hot-rolled by multiple passes in air. Shearing and peeling tests were performed according to appropriate standards to evaluate the bonding results. The interfacial microstructures, composition diffusion and peeling fractographies of the clad plate samples were used to examine the bond quality. The effects of bond parameters on the bond properties of clad plate were studied. The experimental results indicate that the shear strength reaches 266 MPa, and the peel strength is up to 322 N/mm at 1323 K in the first pass, representing a reduction of 24.3%. Both the shear strength and the peel strength increase with increases in bonding temperature and total reduction ratio. The maximum shear strength reaches 361 MPa, and the peel strength is up to 510 N/mm at 1323 K after six passes with a total reduction ratio of 74.8%. Both the dimension and number of interfacial pores decrease rapidly with increasing rolling passes. Multipass hot rolling generates a number of local embedments at the interface and improves the interfacial bonding strength.     

界面对铜/铝异步轧制层状复合材料组织与性能的影响

利用异步轧制复合技术和退火工业制备铜/铝层状复合材料,利用扫描电子显微镜观察界面微观组织和拉伸断口形貌,进行剥离和拉伸实验研究界面的力学性能。结果表明,热处理过程促进了界面层的形成,而较高的退火温度破坏了界面结合。层状复合材料的拉伸性能介于两组元金属之间。经340℃退火后,铜基体的延伸性能与铝基体接近,并且界面开裂程度较低。在拉伸过程中,两金属基体延伸率不同,导致界面发生内部断裂。界面作为铜、铝之间的过渡层,在强化复合材料方面起到重要作用。     

工艺参数对高强度钢强度及韧性的影响

通过两阶段控制轧制加快速冷却,综合利用细晶强化、相变强化和析出强化等强化机制获得了满足了国标GB/T 16270-1996中Q550和Q620要求的高强度钢板。通过光学显微镜、扫描电镜和背散射衍射手段研究了终冷温度及终轧温度对力学性能的影响。结果表明,随终冷温度降低,屈服强度、抗拉强度和屈强比升高;终轧温度高不利于组织的细化,导致强度和韧性降低;随终冷温度升高,M-A岛的尺寸增大,体积分数增多,不利于韧性和塑性的提高。     

异步轧制对3004铝合金变形织构及制耳率的影响

以３００４铝合金为实验材料，研究了异步轧制对该合金的变形织构以及相应的制耳率的影响。实验表明：异步轧制和同步轧制板的主要变形织构是相同的，均为纯铜型织构｛１１２｝＜１１１＞＋｛２１３｝＜３６４＞＋｛１１０｝＜１１２＞，但异步轧制产生的变形织构较同步轧制的强度高，且随异步轧制速比的提高而增强。同时，异步轧制的板材中还出现｛００１｝＜１１０＞织构。另外，在相同压下率的情况下，异步轧制板材的深冲制耳率均大于同步轧制的制耳率     

Special features of the winding bend test

Summary

This paper deals with the resistance spot weldability of steel to aluminium alloy using an intermediate layer of aluminium clad steel. Five types of clad sheet with various steel/aluminium thickness ratios were produced by hot rolling. The mechanical properties of the clad sheet changed with the thickness ratio and ranged between those of steel and:those of aluminium sheet. The peel strength of the steel/aluminium interfaces was greater than 25 N/mm.

Materials used in spot welding were 0.8 mm thick EDDQ steel sheet, three types of 1.0 mm thick aluminium alloy sheet and the clad sheet mentioned above. Spot‐weldability, including suitable welding current, nugget diameter, tensile shear strength and thickness of the intermetallic compound layer formed at the interface of the clad sheets, changed with the thickness ratio of the clad sheet. From these results, it was concluded that spot‐weldability was affected by the thickness ratio of the clad sheets.

Spot‐weldability was also affected by the alloying elements in the aluminium alloy sheet. Tensile shear strength and nugget diameter varied in various types of aluminium alloy sheet.