Research on horizontal electromagnetic continuous casting of copper tube blanks

1. IntroductionCopper tubes are widely used in refrigerating andair-conditioning units. In recent years, traditional barecopper tubes have been gradually replaced byinner-grooved ones to improve the efficiency ofthermal-exchange for energy saving and environmental-protection [1].Based on the statistics of the Chineserefrigerating industry union, the demand for household airconditioners will be 30.5 million in 2005, which meansthat 91.6 thousand tons inner-grooved copper tubes willbe needed[1].…     

Microstructure and properties of ductile iron bars for plunger pump prepared by horizontal continuous casting process

Ductile iron bars(DIBs) with a diameter of 145 mm, used for plunger pump production, were made by the horizontal continuous casting(HCC). The microstructure of the samples cut at three locations with different distances away from the surface(~20 mm from the surface, half of the radius and the center of the HCCDIBs)were investigated. The mechanical properties were measured by tensile and torsion tests. Results show that after the spheroidization of graphite, the iron matrix incorporates the nodules of Format I, Size 8 close to the surface, Format I, Size 7 at the half of the radius from the surface, and Format II, Size 6 in the centre of the bar,according to the ASTM A247 standard. The content of pearlite in the matrix changes from 55%(~20 mm from the surface) to 70%(half of the radius) and 80%(the center of the HCCDIBs). The strengths in tension are 552, 607 and 486 MPa with the elongations of 12.5%, 10.5% and 5.8% in samples cut at these three locations from the surface to the centre, respectively. The strength in torsion is equal to 558, 551 and 471 MPa at corresponding torsion angles of 418°, 384° and 144° respectively to the same distance from the bar surface. Fracture in tension is manifested via crack propagation through the interface between graphite nodules and matrix(Mode I), while in torsion the fracture is caused by the shear of graphite nodules(Mode II). It is shown that the transition between two fracture modes is also dependent on the size of graphite nodule. Typically, fracture Mode I was observed for nodules of smaller diameter(less than 22.7 μm) and fracture Mode II was seen for nodules of greater diameter(more than 24.8 μm).     

Numerical simulation of temperature field of copper and copper alloy in horizontal continuous casting

１ＩｎｔｒｏｄｕｃｔｉｏｎＢｅｃａｕｓｅｏｆｔｈｅｈｉｇｈｅｆｆｉｃｉｅｎｃｙａｎｄｅｎｅｒｇｙｓａｖｉｎｇｓ，ｔｈｅｃｏｎｔｉｎｕｏｕｓｃａｓｔｉｎｇｔｅｃｈｎｏｌｏｇｙｉｓｗｉｄｅｌｙａｐｐｌｉｅｄ．Ｃｏｎｔｉｎｕｏｕｓｃａｓｔｉｎｇｉｓｄｉｆｆｅｒｅｎｔｆｒｏｍｏｒｄｉｎａｒｙｃａｓｔｉｎｇｉｎｗｈｉｃｈｔｈｅｍｅｔａｌｌｉｑｕｉｄｉｓｎｏｔｃａｓｔｉｎｔｏａｓｉｎｇｌｅｍｏｌｄ，ｂｕｔｓｔｅａｄｉｌｙｉｎｔｏａｍｏｌｄｃｏｏｌｅｄｂｙｗａｔｅｒ，ａｎｄｔｈｅｓｏｌｉｄｉｆｉｅｄｍｅ…     

结晶器陶瓷内衬复合铜管的研究和应用

自蔓延高温合成是一种新的材料合成技术，具有能耗低、合成时间短、产量高、产品高纯度、合成物无污染等优点。将自蔓延高温合成技术与离心铸造技术结合，开发了陶瓷内衬复合铜管技术，可在钢管内表面涂敷耐磨性和耐蚀性优良的陶瓷涂层。为提高陶瓷涂层致密度、韧性和结合强度，研究了添加剂的影响。陶瓷内衬复合铜管应用于管式结晶器，可提高使用寿命，降低成本。     

连续铸造铜单晶的力学性能和电阻率

采用自制水平单晶连铸设备制备铜单晶, 并对铜单晶的力学性能和电阻率进行了测试分析。结果表明,铜单晶与多晶铸棒比,抗拉强度降低２０ ．８５ ％ ,屈服强度降低８６ ．５４ ％ ,延伸率增加８０ ．２４ ％ , 断面收缩率增加３９４ ．５０ ％ ; 与轧制棒比, 抗拉强度降低６５ ．９７ ％ , 屈服强度降低９８ ．２７ ％ , 延伸率增加２７０ ．００ ％ , 断面收缩率增加４ ．００ ％ ; 与多晶铸棒比电阻率降低１５ ．５７ ％ , 与定向凝固铸棒比电阻率降低４ ．２４ ％ 。因此, 连铸铜单晶具有非常优异的塑性加工性能和低电阻率     

20钢水平连铸圆管坯轧制的钢管内部发纹研究

介绍了用水平连铸圆管坯轧制钢管的内部发纹及显微组织情况 ,得出内部发纹是一种由 (Mn、Fe)S和疏松点、α -Fe构成的偏析带 ,是由管坯带来的 ;轻微内部发纹的存在对钢管的使用性能不会造成较大影响。     

热冷组合铸型水平连铸Cu-0.36Be-0.46Co合金带材冷轧过程中显微组织和力学性能变化（英文）

采用热冷组合铸型(HCCM)水平连铸工艺制备300 mm(宽)×10 mm(厚) Cu-0.36%Be-0.46%Co(质量分数)合金带材,对连铸带材进行冷轧,研究轧制过程中合金显微组织和力学性能的变化规律与变形机理。结果表明:连铸带材具有沿长度方向的柱状晶组织,表面质量好,断后伸长率达到35%,无需表面处理可直接进行大变形冷轧加工,无中间退火的累积冷轧变形量达98%。当变形量较小时(20%),变形机理为位错滑移,形成大量弥散分布的位错和位错胞;当变形量为40%时,合金中出现形变孪晶,且孪晶与位错胞相互作用形成长条状位错胞;当变形量超过60%时,形成切变带,发生明显的微区晶体转动;随着变形量的进一步增大,切变带数量增多且相互作用,使晶粒明显细化。抗拉强度和硬度由铸态的353 MPa和HV 119分别升高至冷轧变形量95%时的625 MPa和HV 208,断后伸长率则由35%降低至7.6%。该结果可为发展铍铜合金带材HCCM水平连铸-冷轧短流程高效加工方法提供实验依据。     

Microstructure and properties of Cu-0.6Cr alloy after vacuum continuous casting

To promote the solution of chromium in copper and the purity of copper-chromium （Cu-Cr） alloy, vacuum continuous casting （VCC） process was employed to fabricate the Cu-Cr alloy required for electrode material. Cu-0.6Cr （containing 0.6%（mass fraction） chromium） alloy bar with a diameter of 12 mm was cast with a constant rate of 250 mm/min. The microstructure, mechanical properties, and physical properties were discussed. After solid solution strengthening and aging treatments, Cu-0.6Cr alloy fabricated by VCC process has higher tensile strength （σ≥314 MPa）, elongation rate （δ≥34%）, conductivity （≥80.5% IACS）, and hardness （80 HRB） compared to the as-cast alloy.     

连铸AZ31镁合金的热挤压变形组织与性能(英文)

文章研究了电磁连铸AZ31镁合金经热挤压变形后的微观组织和力学性能。结果表明,挤压过程中的动态再结晶能够显著细化晶粒,局部细晶区的平均晶粒为2μm。与铸态合金相比,挤压后的AZ31镁合金具有更细小的晶粒和更均匀的微观组织。挤压变形后产生强烈的基面织构;挤压后材料的力学性能显著提高。屈服强度、抗拉强度和断面收缩率随着挤压比的增大而增大。挤压比为25时,屈服强度、抗拉强度和断面收缩率分别为259MPa,357MPa和30.5%,比铸态合金分别提高了86.33%,64.52%和67.40%。随着挤压比的增大,晶粒细化效果更为明显,微观组织更均匀。断口形貌分析表明,挤压变形后材料由韧脆混合型断裂,转变为韧性断裂。     

Characteristics of copper-clad aluminum rods prepared by horizontal continuous casting

An innovative horizontal continuous casting method was developed and successfully used to prepare copper-clad aluminum (CCA) rods with a diameter of 85 mm and a sheath thickness of 16 mm. The solidification structure and element distribution near the interface of the CCA ingots were investigated by means of a scanning electron microscope, an energy dispersive spectrometer, and an electron probe X-ray microanalyzer. The results showed that the proposed process can lead to a good metallurgical bond between Cu and Al. The interface between Cu and Al was a multilayered structure with a thickness of 200 μm, consisting of Cu₉Al₄, CuAl₂, α-Al/CuAl₂ eutectic, and α-Al + α-Al/CuAl₂ eutectic layers from the Cu side to the Al side. The mean tensile-shear strength of the CCA sample was 45 MPa, which fulfills the requirements for the further extrusion process. The bonding and diffusion mechanisms are also discussed in this paper.     

Comparison of phosphor bronze metal sheet produced by twin roll casting and horizontal continuous casting

Much effort recently has been expended to study the strip casting process used to produce thin metal strip with a near final thickness. This process eliminates the need for hot rolling, consumes less energy, and offers a feasible method of producing various hard-to-shape alloys. The finer microstructure that results from the high cooling rate used during the casting process enhances mechanical properties. In this study, strips of phosphor bronzes (Cu-Sn-P) metal were produced using a twin roll strip casting process as well as a conventional horizontal continuous casting (HCC) process. The microstructures, macrosegregations, textures, and mechanical properties of the as-cast and as-rolled metal sheet produced by these two methods were examined carefully for comparative purposes. The results indicate that cast strip produced by a twin roll caster exhibit significantly less inverse segregation of tin compared to that produced by the HCC process. The mechanical properties including tensile strength, elongation, and microhardness of the products produced by the twin roll strip casting process are comparable to those of the HCC processed sheet. These properties meet specifications JIS H3110 and ASTM B 103M for commercial phosphor bronze sheet. The texture of the as-rolled sheet from these two processes, as measured from XRD pole figures, were found to be virtually the same, even though a significant difference exists between them in the as-cast condition.     

电磁场作用下铜板带水平连铸熔体的流动和凝固特征

为了消除铜板带水平连铸中的微气孔、夹杂和柱状晶对接等凝固问题,提出一种基于正交磁场和直流电流相互作用的结晶器内水平电磁搅拌,并在实验室物理模拟实验的基础上,进行现场工业实验。在模拟实验中,用超声波多普勒测速仪测量该电磁搅拌下水平连铸结晶器内金属液的流动规律,并与生产实验中锌白铜板带的凝固特征相互印证,发现搅拌电流达到400A时,板带内部气孔消失,电流达到500A时板带出现等轴晶带,电流达到800A时板带坯偏析率趋于零。     

上引-连续挤压法制备Cu-Cr-Ag合金组织性能的研究

本文采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)等分析测试手段系统研究不同热处理工艺制度对上引-连续挤压法制备Cu-Cr-Ag合金微观组织性能的影响规律。试验结果表明,上引连铸Cu-Cr-Ag合金棒坯经连续挤压过程中合金发生了强烈的剪切变形,晶粒破粹明显,其晶粒平均尺寸为4～5μm。挤压后合金经60%变形,875℃×1h固溶处理,60%变形,450℃不同时效处理后,其维氏硬度与时效时间的关系呈先下降后上升再下降的趋势,而导电率与时效时间的关系呈先快速上升后缓慢增加最后趋于稳定的趋势。析出相的析出序列为过饱和固溶体→G.P 区→f.c.c Cr相→有序化→b.c.c Cr相,且b.c.c Cr相与基体的取向关系呈N-W关系。     

Microstructure and properties of continuous casting Ag-28Cu-8Sn alloy fabricated by dieless drawing

Ag-28Cu-8Sn(wt%) alloy is a widely used brittle silver-based brazing filler metal.The wire of brazing filler metal was prepared by continuous casting process and dieless drawing technology.The phase structure was measured by X-ray diffraction(XRD),and the microstructure of wetting interface,cast states,processing states and fracture morphologies were characterized by the optical microscopy(OM) and scanning electron microscopy(SEM),respectively.The electrical conductivity,hardness,tensile strengt...     

薄壁白铜管坯电磁连铸

为获得高质量的薄壁白铜管坯,提出了在水平连铸过程中施加旋转电磁场的管坯连铸新方法,并采用BFe10-1-1合金进行实验,考察了电磁场对白铜管坯表面质量、凝固组织和力学性能的影响。结果表明：在连铸过程中施加旋转电磁场能够提高金属液的流动性和充型能力,消除表面裂纹缺陷,从而制备出表面光滑的薄壁白铜管坯;在电磁力的作用下管坯凝固组织显著细化,富镍相由针状转化为团块状,同时铸造应力由未施加电磁场时的7．2MPa下降至0．32MPa：随着凝固组织的改善,施加磁场的管坯抗拉强度和伸长率与未施加磁场管坯的相比分别提高5％和36％。     

连铸直接成形矩形断面铜包铝复合材料界面及其在轧制中的变化

采用水平连铸直接复合成形工艺,制备断面尺寸为50 mm×30 mm、铜包覆层厚度为3 mm的铜包铝复合棒材,并分别采用拉剪试验、XRD、SEM、EDS和EPMA等对铸棒界面的结合强度、形貌和组成进行表征。结果表明:铜包铝复合铸棒界面层的主要组成为CuAl2和Cu9Al4,在近铜侧由平面状Cu9Al4(Ⅰ区)和CuAl2胞晶(Ⅱ区)两区组成;在近铝侧为α(Al)+CuAl2共晶组织(Ⅲ区)。在铸棒横断面上不同位置的界面层结构相同,但界面总厚度不均匀,上部厚度最大,达到220μm,且CuAl2胞晶组织较发达;侧部厚度最小,约为110μm;下部厚度为150μm。界面层总厚度,特别是Ⅱ区CuAl2胞晶层厚度对界面剪切强度有显著影响,因而横断面上部的界面剪切强度较低,为24.7 MPa;侧部和下部的界面剪切强度接近,分别为35.6和33.4 MPa。XRD和断口分析表明,界面分离发生在界面层的Ⅰ区和Ⅱ区内。在后续轧制加工过程中,界面层发生断裂而破碎,其破碎程度随变形程度的增加而增加;当压下率达到67.7%以上时,形成大量纯铜和纯铝直接接触无明显扩散的结合界面,原界面化合物层破碎为尺寸较小的碎片沿界面不连续分布。     

三辊行星轧制过程中ACR紫铜管的组织和性能演变

采用金相显微镜、布氏硬度仪以及激光热导仪对三辊行星轧制过程中紫铜管的组织和性能进行研究。结果表明:在三辊行星轧制过程中,先后存在着加工硬化和动态再结晶软化两个过程,急剧大变形使粗大的铜晶粒破碎、滑移并产生大量热量,致使变形区温度急剧上升,最终获得了动态再结晶组织;与组织转变相对应,硬度值表现为随变形量的增大而增加,因加工硬化和动态再结晶的共同作用保持稳定,再结晶完成时硬度值下降;由于空洞等缺陷在变形过程中被抵消,材料的热导率增大,再结晶开始后,晶粒变得细小,热导率下降。     

Characteristics of clad aluminum hollow billet prepared by horizontal continuous casting

The 3003/4045 clad hollow billets are prepared in the present study. Microstructures, solute distribution and bonding strength of the interfacial regions were investigated. The effects of plastic deformation on the evolution of microstructure and microhardness of the interfaces were also studied. The results show that metallurgical bonding between the solid and liquid Al alloys can be obtained with optimal parameters. Si and Mn atoms diffuse across the interface to form a diffusion layer with the thickness about 30 μm on average. The mean tensile-shear strength of as-cast clad hollow billet is 85.3 ± 9.2 MPa, and the strength of the interface is higher than that of 3003 alloy. Incompatible deformation between 3003 and 4045 layers occurs during rolling processes, and the needle-like Si phase transforms to the dispersive particles. The gradient distribution of microhardness across the interface is retained after the deformation.     

Microstructure and material properties of an Al–Cu alloy provided by the Ohno continuous casting technique

The specific objective in this work is an exploration of the material properties produced by a recently developed continuous casting technique. The study focuses on an Al–Cu alloy provided by the Ohno continuous casting process. The experimental approaches give rise to unusual microstructural characteristic in the cast samples, namely a fine lamellar eutectic structure with unidirectional growth along its axial direction together with a regularly oriented lattice structure. Such microstructural characteristics significantly increase the tensile and fatigue properties.     

矩形断面铜包铝复合材料的水平连铸直接复合成形

制备断面尺寸为50 mm×30 mm、铜包覆层厚度为3 mm的矩形断面铜包铝复合材料,研究结晶器长度、拉坯速度、芯管长度和一次冷却水流量对矩形断面铜包铝复合材料水平连铸直接复合成形过程的影响。结果表明:当连铸结晶器长度为150 mm、芯管长度为125 mm时,较为合理的拉坯速度范围为75~90 mm/min;当拉坯速度过慢时,铝液的填充不连续,导致芯部铝的收缩或冷隔等缺陷;当拉坯速度过快时,铜铝界面反应严重;当拉坯速度为75 mm/min时,合理的一次冷却水流量为700 L/h,一次冷却水流量大于1 000 L/h导致铝液填充不连续,一次冷却水流量小于400 L/h则导致铜铝界面反应加剧。通过检测芯管出口位置处的石墨内衬温度变化可有效监控铝液的填充行为以及连铸过程的稳定性。