2024铝合金2700mm×550mm扁锭铸造工艺研究

采用Almex铸造机,试验研究大规格2024铝合金扁锭的铸造工艺。结果表明:通过控制Fe元素和Be元素的含量可以改善铸锭的表面质量,提高铸造成功率;在铸造温度680℃～690℃、铸造速度25 mm/min～45 mm/min、水流量控制在20 m3/h～80 m3/h、结晶器中的铝液位高度60 mm的工艺参数下,可以铸造出规格为2 700 mm×550 mm的2024铝合金扁锭,提高了铸锭的成品率,降低生产成本。铸造出的扁锭表面无皱褶、裂纹、锭尾塌陷等缺陷,铸锭组织、成分均匀,晶粒度细小,满足用户需求。     

不同尺寸大规格铝合金扁锭同时铸造的工艺研究

使用wagstaff铸造机,试验研究不同尺寸大规格铝合金扁锭同时铸造的工艺。结果表明,采用铸造温度690℃~710℃,铸造速度25 mm/min~50 mm/min,结晶器中的液位高度65 mm,冷却水流量控制为13 m~3/h~80 m3/h,结晶器布设方式为中心对称,可以实现一次铸造厚度550 mm、宽度变化在1 910 mm~2 570 mm范围内的两块大规格铝合金扁锭。铸造出的扁锭表面无皱褶、裂纹、锭尾塌陷、通裂等缺陷。通过直读光谱分析化学成分、高低倍组织检查,发现其扁锭的组织、成分均匀,晶粒度细小,满足用户使用要求。     

扁锭铸造方式对高压阳极铝箔生产质量的影响

采用隔热模铸造和普通铜模铸造进行试验对比,分析不同铸造方式对高纯铝铸造扁锭微观组织和外观质量控制的影响,以及对高压阳极铝箔最终成品的立方织构强度影响程度。结果表明,隔热模铸造的扁锭表面光亮,仅扁锭头部存在60 mm~80 mm长的严重冷隔、偏析等(需切除),其他部分无冷隔;而铜模铸造扁锭表面冷隔明显,头部约200 mm长的部分有明显冷隔、偏析等(需切除)。隔热模铸造扁锭表层等轴细晶区层厚度较浅,边部看不到明显柱状晶区;而普通铜模铸造扁锭边部约有10 mm~12 mm的明显柱状晶区,铣面深度更大。从切头长度和铣面深度看,隔热模铸造扁锭的成品率明显更高。与此同时,隔热模铸造扁锭晶粒立体外形更细长,晶粒边界更模糊,金属冷却方向流更明显,但经后续热处理和轧制后其内部组织与铜模铸造的差异性大幅缩小。从最终成品的立方织构含量对比看,隔热模铸造的立方织构含量相对更高,平均增幅达到1.47%,从立方织构的普遍要求和控制基数已经达到96%以上看,这个增量不可忽视。因此,隔热模铸造对生产高压阳极铝箔生产仍非常有利。     

7075铝合金2540mm×550mm规格扁锭铸造工艺研究

试验研究了大规格7075铝合金扁锭的铸造工艺。结果表明:通过控制Fe、Si元素的含量可以改善铸造裂纹;采用软起铸,当铸造速度为40 mm/min～50 mm/min、铸造温度为675℃～685℃、冷却水温度为35℃～40℃、冷却水流量为40 m~3/h～70 m~3/h、结晶器液位高度60 mm～100 mm的条件下,铸造出表面无皱褶、裂纹、锭尾塌陷和成分均匀、晶粒细小的7075铝合金扁锭。解决了用2 540 mm×550 mm规格的7075铝合金扁锭生产航空货运用成品宽度超过2 300 mm的宽幅铝板必须横轧的问题,提高了成品率的同时降低了生产成本。     

半连续铸造中脉冲水冷却技术对扁锭底部翘曲的影响

采用常规铸造法和脉冲水冷却法对比研究了不同铸造工艺对400mm×1320mm工业纯铝扁锭底部翘曲的影响规律。在铸造温度为720℃,铸造速度为35～65mm·min-1,冷却水流量为20～50m3.h-1的工艺条件下,采用常规铸造和脉冲水冷却时扁锭的底部翘曲变形量分别为52mm和5～12mm。脉冲水冷却法对铸锭底部翘曲的抑制主要是由于脉冲水对铸锭的冷却强度降低,铸锭芯部和边部的冷却差异减小,在减小翘曲驱动力的同时增加了铸锭底部凝固壳的刚度,从而抑制了底部翘曲。     

7055铝合金扁锭铸造工艺研究

利用Almex铸造机,试验研究7055铝合金扁锭的铸造工艺,并对铸锭的化学成分和显微组织进行了分析。试验结果表明:采用高效铝熔体洁净技术,保证了熔体质量;采用软起铸的铸造工艺,可促进铸锭成形,降低开裂倾向;通过多级可控温铝制结晶器进行铸造,浇注温度在700～710℃,结晶器水流量控制为15 m3/h～60 m3/h,铸造速度为30 mm/min～50 mm/min,结晶器液位高度为70 mm～105 mm,获得了外观质量良好、内部成分均匀、高倍组织细小的7055铝合金扁锭。     

AZ31B镁合金400mm×1200mm扁锭铸造流量控制的改进

铸造AZ31B镁合金400 mm×1 200 mm扁锭时,扁锭易产生冷隔。其主要原因是铸造系统的气路压力不稳,导致结晶器内镁合金液面忽高忽低。通过增加气动定值器与镁液分流器杠杆,可以保持结晶器内镁合金液面的高度稳定,从而减少扁锭的冷隔,使其成品率大大提高。     

电解铝液生产大尺寸扁锭工艺技术研究

分析了影响铝合金铸锭质量的主要因素,总结了用电解铝生产大扁锭关键熔炼、铸造工艺.通过控制合理的冷却强度、铸造温度、铸造速度、结晶器液面高度等工艺参数,生产出优质大尺寸扁锭.     

用电解铝液铸造铝合金热轧锭坯的关键技术

用电解铝液直接配料,采用低液位铸造技术生产热轧用优质扁锭,首先要针对电解铝液温度高、金属及非金属夹杂物多、空气含量高的特点,采取严格的熔体净化工艺为铸造提供洁净铝熔体;其次要针对低液位带组合结晶器全自动铸造技术特点,根据合金特性、扁锭规格和铸造条件,设定最佳的铸造工艺参数.     

低液位铸造法生产大规格铝合金扁锭的关键技术

用电解铝液配料,采用低液位铸造技术生产高精度铝板带用的优质扁锭,首先要针对电解铝液温度高、夹杂物多、气体含量高的特点,采取严格的熔体净化工艺,为铸造提供洁净的铝熔体;其次要针对低液位及组合结晶器全自动铸造技术的特点,根据合金特性、扁锭规格和铸造条件,设定最佳铸造工艺参数。     

The tilt casting process

Tilt casting is a process with the unique feature that, in principle, liquid metal can be transferred into a mould by simple mechanical means under the action of gravity, but without surface turbulence. It therefore has the potential to produce very high quality castings. Even so, the process is not often optimised in the industrial environment. This investigation represents an attempt to investigate some fundamental problems associated with the process.

A computer controlled, programmable roll-over casting wheel with a diameter of 1 m was used to produce sand castings in an Al-4.5% Cu alloy. The filling of the mould was studied using realtime X-ray radiography. Real-time X-ray radiography revealed that the molten metal could exhibit tranquil, turbulent or chaotic flow into the mould during tilt casting, depending on (i) the angle of tilt of the mould at the start of casting, and (ii) the tilting speed. Essentially horizontal transfer of the melt could achieve tranquil filling of the mould with minimum surface turbulence by a tilt starting position above the horizontal. The tensile properties of castings made using various starting conditions and rotation rates were measured and the results analysed using Weibull statistics to quantify reliability. Results are summarised on a map of the various operating regimes for tilt casting. An operational window for the production of reliable castings has been defined for the first time.     

汽车压铸及铸造铝合金

介绍了汽车铝合金中压铸、铸造合金的比例,变化趋势,在某些国家地区的产量。详细介绍了日本和美国近些年来各类汽车铝材的发货量,中国和日本压铸、铸造铝合金的化学成分、性能、特点及应用,各种铸造铝合金的热处理规范,汽车用高强度铸造铝合金的特点,典型汽车铸造铝产品的选材、生产与性能。介绍了压力铸造、金属型低压铸造、科斯沃斯法、气化模铸造工艺,列出了低压铸造工艺生产的各类铸件特征、材料和工艺。预测了汽车用铝的前景。     

Stability condition of semisolid continuous casting process

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电解铝铸造过程金属损耗的预防

对电解铝铸造过程中目前存在的主要问题和影响金属损失的因素进行了分析,认为工艺上可能存在有溜槽过长、垂直导流点多、炉温炉压失控等问题,从而导致铝液的紊流、高温并与复杂炉气的反应,以及精炼扒渣的影响,这些因素均可引起金属氧化损耗增多。为此,提出了相应的改进措施。     

Early movable metal types produced by lost-wax casting

The oldest extant movable metal print book is Buljojikjisimcheyojeol (Jikji) [1–9], printed in Korea in 1377. The prevailing assertion has been that the movable metal type used in its printing was made through lost-wax casting [3–6]. Unfortunately, however, there is no record of movable metal type being made from lost-wax casting, and to this day no relics have been found supporting this claim. We report that the first known movable metal types having the features of lost-wax casting are found in the Wibuinja, the movable metal type of the Joseon Dynasty Period that is preserved by the National Museum of Korea. The tapered shape of the body of the movable type and the unevenness of the stripe before casting defects broke out both suggest use of the lost-wax casting method. Although our findings do not conclusively prove that the movable metal type used for Jikji was made through lost-wax casting, the possibility of its production from lost-wax casting cannot be excluded because movable metal types made from lost-wax casting exist.     

Investment casting of AZ91HP magnesium alloy

This paper describes AZ91HP magnesium alloy investment casting. The aim of this study is to optimize the process for magnesium investment casting. Special attention was given to evaluating the thermal stability of oxides against molten AZ91HP magnesium alloy. The oxides examined included CaO, CaZr0₃, and silica bonded A1₂0₃ and ZrSi0₄. Also, the microstructural features of the as-cast alloy were investigated, and the effect of the processing parameters on the microstructure and mechanical properties were evaluated describing the grain size, hardness and ultimate tensile strength of the as-cast alloy.     

Performance of stainless steel foams produced by infiltration casting techniques

Ferritic (AISI 430) and austenitic (AISI 304) stainless steel foams were produced exploiting a process based on molten metal infiltration on ceramic model. In particular, SiC foundry filter was used as space holder and, after the solidification, it has been removed by hydrofluoric acid. The produced foams are featured by three different porosity grades (10, 20 and 30 PPI) and by constant relative density (0.60). The morphology, the mechanical properties and the corrosion resistance were studied and the results were correlated to the material, the porosity, the size and the distribution of the voids. Morphologically, the structure is arboreous open-cell foam featured by interconnected cavities. This aspect, combined with the high relative density, assures high compressive plateau stress, structural integrity and good deformability. The corrosive tests, according to the ASTM A262-Met.B and NACE TM-0284, permitted to identify possible application fields for these products.     

Interfacial heat transfer behavior at metal/die in finger-plated casting during high pressure die casting process

Heat transfer at the metal-die interface has a great influence on the solidification process and casting structure. As thin-wall components are extensively produced by high pressure die casting process(HPDC), the B390 alloy finger-plate casting was cast against an H13 steel die on a cold-chamber HPDC machine. The interfacial heat transfer behavior at different positions of the die was carefully studied using an inverse approach based on the temperature measurements inside the die. Furthermore, the filling process and the solidification rate in different finger-plates were also given to explain the distribution of interfacial heat flux(q) and interfacial heat transfer coefficient(h). Measurement results at the side of sprue indicates that qmax and hmax could reach 9.2 MW·m~(-2) and 64.3 kW ·m~(-2)·K~(-1), respectively. The simulation of melt flow in the die reveals that the thinnest(T_1) finger plate could accelerate the melt flow from 50 m·s~(-1) to 110 m·s~(-1). Due to this high velocity, the interfacial heat flux at the end of T_1 could firstly reach a highest value 7.92 MW·m~(-2) among the ends of T_n(n=2,3,4,5). In addition, the q_(max) and h_(max) values of T_2, T_4 and T_5 finger-plates increase with the increasing thickness of the finger plate. Finally, at the rapid decreasing stage of interfacial heat transfer coefficient(h), the decreasing rate of h has an exponential relationship with the increasing rate of solid fraction(f).     

离心铸造WC颗粒增强钢基复合材料辊环的研制

介绍了WCp/钢基复合材料轧辊的材料选择和制备工艺 ,并对其显微组织及力学性能进行了分析。工业实验结果表明 :复合材料轧辊的寿命比普通Cr12轧辊高 3倍以上     

半固态复合熔铸过程中SiC与2A11合金的润湿性

研究了SiC增强铝基复合材料的半固态法制备, 分析了SiC颗粒与基体金属之间的润湿性, 提出了解决SiC颗粒与基体金属之间润湿的措施. 结果表明 将SiC颗粒进行高温处理, 在其表面涂覆K2ZrF6, 在2A11合金熔体中添Mg元素, 可改变SiC与铝基体的浸润性.