Solidification process and microstructure of transition layer of Cu-Al composite cast prepared by method of pouring molten aluminum

The Cu?Al composite casts were prepared by the method of pouring molten aluminum. The solidification process and themicrostructure of the transition layer were investigated during the recombination process of the liquid Al and the solid Cu. The results reveal that the microstructure of the transition layer in the Cu?Al composite cast consists of α(Al)+α(Al)?CuAl2 eutectic,α(Al)?CuAl2 eutectic, CuAl2+α(Al)?CuAl2 eutectic and Cu9Al4. Additionally, the pouring temperature, cooling mode of the Cu platesurface and start time of the forced cooling after pouring have no effect on the microstructure species. But the proportion of thevarious microstructures in the transition layer changes with the process parameters. The pure Al at the top of the transition layer startsto solidify first and then the α(Al) phase grows in a dendritic way, while the CuAl2 phase exhibits plane or cellular crystal growth from the two sides of the transition layer towards its interior. The stronger the cooling intensity of the Cu plate outer surface, the more developed the dendrite, and the easier it is for the CuAl2 phase to grow into a plane crystal.

Refinement of primary Si grains in Al–20%Si alloy slurry through serpentine channel pouring process

In this study, a serpentine channel pouring process was used to prepare the semi-solid A1-20%Si alloy slurry and refine primary Si grains in the alloy. The effects of the pouring temperature, number of curves in the serpentine channel, and material of the serpentine channel on the size of primary Si grains in the semi-solid A1-20%Si alloy slurry were investigated. The results showed that the pouting temperature, number of the curves, and material of the channel strongly affected the size and distribution of the primary Si grains. The pouring tempera- ture exerted the strongest effect, followed by the number of the curves and then the material of the channel. Under experimental conditions of a four-curve copper channel and a pouring temperature of 701℃, primary Si grains in the semi-solid A1-20%Si alloy slurry were refined to the greatest extent, and the lath-like grains were changed into granular grains. Moreover, the equivalent grain diameter and the average shape coefficient of primary Si grains in the satisfactory semi-solid A1-20%Si alloy slurry were 24.4 μm and 0.89, respectively. Finally, the re- finement mechanism and distribution rule of primary Si grains in the slurry prepared through the serpentine channel pouring process were analyzed and discussed.

Influence of rheo-diecasting processing parameters on microstructure and mechanical properties of hypereutectic Al-30%Si alloy

The effects of pouring temperature,vibration frequency,and the number of curves in a serpentine channel,on themicrostructure and mechanical properties of Al-30%Si alloy processed by rheo-diecasting(RDC)were investigated.The semisolidAl-30%Si alloy slurry was prepared by vibration serpentine channel pouring(VSCP)process in the RDC process.The results showthat the pouring temperature,the vibration frequency,and the number of the curves strongly affect the microstructure and mechanicalproperties of Al-30%Si alloy.Under experimental conditions of a pouring temperature of850°C,a twelve-curve copper channel anda vibration frequency of80Hz,the primary Si grains are refined into fine compact grains with average grain size of about24.6μm inthe RDC samples assisted with VSCP.Moreover,the ultimate tensile strength(UTS),elongation and hardness of the RDC sample are296MPa,0.87%and HB155,respectively.It is concluded that the VSCP process can effectively refine the primary Si grains.Therefinement of primary Si grains is the major cause for the improvement of the mechanical properties of the RDC sample.

Refinement of primary Si grains of A390 alloy slurry through serpentine channel pouring process

In this paper, the serpentine channel pouring process for preparing a semi-solid A390 alloy slurry and refining the primary Si grains of the A390 alloy, was used. The effects of the pouring temperature, the cooling water flow and the number of the curves on the size of the primary Si grains in the semi-solid A390 alloy slurry were investigated. The results show that the pouring temperature, the cooling water flow and the number of the curves have a major effect on the size and the distribution of primary Si grains. Under the experimental condition of the four-curve copper channel whose cooling water flow was 500 L·h-1 and the pouring temperature was 690 oC, the primary Si grains of the semi-solid A390 alloy slurry were refined to the greatest extent and the lath-like grains were changed into granular ones. Additionally, the equivalent grain diameter and the average shape factor of the primary Si grains of the satisfactory semi-solid A390 alloy slurry are 18.6 μm and 0.8, respectively. Further, the refinement mechanism of the primary Si grains through the serpentine channel pouring process was analyzed and discussed. In summary, the primary Si nuclei could be easily precipitated due to the chilling effect of the channel inner wall, thus the primary Si grains were greatly refined. Meanwhile, the subsequent alloy melt fluid also promoted the separation of primary Si grains from the inner wall, further refining the primary Si grains.

Effect of Pouring Process on the Microstructures of Semi-Solid AlSi_7Mg Alloy

The effect of different pouring temperatures and different pouring heights, the distance between the mouth of the pouring ladle and the top of the mold, on the microstructure of AlSi7Mg alloy have been researched in the paper. When the pouring temperature is close to the liquidus temperature, the primary alpha -Al in 'the billets of AlSi7Mg alloy solidified into spherical and nodular fine grains distributed homogeneously. The optimum pouring temperature for semi-solid AlSi7Mg billet with spherical or nodular primary alpha -Al is 615 degreesC. At the same pouring temperature, the higher the pouring ladle, the more easily the spherical and nodular primary alpha -Al obtained in the semi-solid AlSi7Mg billet. When the pouring temperature is close to the liquidus temperature and the pouring ladle is relatively high, it is the great cooling rate, the flow of the molten allay caused by pouring and the large simultaneous solidification region induced by the near liquidus temperature, that promote the formation of spherical or nodular primary cr-Al.

Study on Image- denoising of Liquid Column in Investment Casting Auto- pouring System

The application of investment casting auto-pouring system can improve the efficiency of manual-pouring system to a certain extent.The judgment of start-stop time depends on the preprocessing of original image collected by the CCD camera.Several methods are presented to denoise the liquid column image.The method of morphological image processing is feasible in theory,and it is important whether to choose the structural element or not.The method of pouring image projection is less affected the image of spure cup.The complexity of image window algorithm is minimal.

寒区某超长隔震结构建造全过程温缩变形分析

针对严寒地区某超长隔震结构建造周期长、平面形状复杂、结构跨度大、季节温差显著及分阶段施工的特点,建立了超长隔震结构建造全过程隔震层温缩变形的计算方法,结合现场的施工进度、方案和步序,采用有限元软件对建造全过程进行了详细的模拟,分析了结构建造全过程隔震层的温缩变形大小及演化规律,并与现场实测结果进行对比验证,最后探讨了结构分阶段施工、施工路径及后浇带设置方式对隔震层温缩变形的影响规律.结果表明:建造全过程温缩变形的模拟结果与实测结果吻合较好,隔震层的温缩变形随着施工进度推移大体呈周期性变化,且与环境温度变化有很大的相关性;超长隔震结构分阶段施工时,各阶段结构之间存在相互约束作用,结构最终的温缩变形是各阶段结构协调变形的结果;合理的施工路径和结构单元划分,能有效减小隔震层的温缩变形;相较于不设置后浇带的情形,当结构后浇带处附加钢筋连通时,隔震层最大温缩变形仅降低了6.3%,而当后浇带处钢筋全部搭接时,隔震层最大温缩变形降低36.3%.

铁水倾倒过程建模和CFD仿真

建立了冶炼铁水倾倒过程数学模型,对铁水倾倒过程进行CFD仿真,探究了钢包内壁倾角θq和初始铁水量V c对铁水倾倒过程中流场、温度场、相界面的影响。仿真结果表明:铁水的温度逐渐降低,铁水的流速先增加后减小。θq的增加使铁水倾倒路径更倾斜,铁水流速增加;V c的增加使铁水流出钢包时间提前、铁水流速增加、流动路径复杂,出现涡流和湍流,转炉内高温区域增大,增加了高温气体从转炉口溢出的量。为了既提高生产效率又保证生产安全,以θq为7°和V c为80%V Q进行铁水倾倒为佳。

作业受限区深基坑溜管法施工技术实践研究

分析了场地情况、基坑深度等工程特点,并根据现场实际需求与经典工程案例相结合,综合考虑浇筑工艺,如机械站位、浇筑速度、浇筑时间、过程成本等影响因素,采用溜管工艺进行大体积混凝土浇筑,在80 h内一次性完成15900 m3的大底板混凝土浇筑。通过科学的温度监控和合理的施工部署,有效把控混凝土浇筑的全过程,确保了大体积混凝土浇筑的顺利进行,在保障混凝土浇筑质量的同时节约成本。

前轴承座上半铸件铸造工艺方案设计与模拟优化

前轴承座上半属于壳体类构件,两侧对称,但壁厚不均匀,材质为HT250。分析铸件结构特点,制定了分别从轴承座底面和顶面浇入的两种底注式浇注方案,分型面皆在轴承座底面。通过数值模拟对两种方案的温度场、速度场、缺陷等进行分析可知,从轴承座顶面浇入的缺陷较大且不利于消除,故选择从轴承座底面浇入的方案,并对此方案进行优化处理。针对铸造过程中产生的缩凹、缩松、缩孔等缺陷,分别增设了冒口、冷铁并进行优化。最终使铸件中的缺陷几乎全部消除,较大的缺陷均集中在浇注系统中,对铸件无影响。

基于华铸CAE的静叶持环砂型铸造工艺参数与缺陷关系的研究

静叶持环砂型铸件中的缩孔、缩松、卷气、变形等缺陷对铸件性能影响很大,采用传统方法对其进行工艺优化难度较高。采用数值模拟和正交试验方法,研究了不同工艺参数对于合金充型凝固后缩孔缩松等缺陷的影响。结果表明,选取合适的浇注温度,适当缩短充型时间,适当提高铸型初始温度,可以有效降低铸件中的缩孔缩松率,选取较高的浇注温度可以降低铸件的变形量。充型时间15 s,浇注温度1590℃,铸型初始温度30℃时,该静叶持环砂型铸件质量最好。分析结果可为静叶持环砂型铸造的设计和制造提供理论和技术支持。

浇注工艺对双金属行星轮轴承复合质量的影响

采用不同铸造工艺参数对某行星轮轴承表面进行ZSnSb11Cu6锡基合金的复合浇注,通过磁粉探伤、超声波探伤及结合强度检测,研究了不同浇注模具、不同合金浇注温度对双金属行星轮轴承复合质量的影响。结果表明:采用金属型模具、合金浇注温度为430℃时可获得比砂型模具、420℃及450℃浇注时更好的合金表面质量和结合强度。经后续工艺验证及小批量生产试制,证实了工艺的稳定性。

转运过程对铁液浇注温度影响的试验研究

通过采用不同的铁液转运工艺方案,随着出铁后时间的改变,研究了转运过程对铁液最终浇注温度的影响;同时,采用不同的出铁重量方案,随着出铁后过程的改变,研究了出铁、出铁时孕育、球化、除渣和倒入浇包等铁液处理过程对铁液温度的影响。结果表明,浇注温度均随转运工艺和转运时间的变化而改变,也会随着转运各过程温度损失的不同而变化。通过试验研究,为最终确定和选用铁液转运工艺和明确转运各过程铁液温度变化提供了指导依据。

连续浇铸复合铸造法制备铝包钢双金属导线

针对包覆焊接法制备铝包钢线工艺复杂、能耗大的缺点,采用连续浇铸复合铸造法制备了铝包钢线,并系统性地研究了浇铸温度对铝包钢线两相结合面的显微组织演变及复合材料性能(硬度、导电率、密度)的影响.结果表明:当浇铸温度为820℃时,在铝和铁两相的界面结合处形成的扩散带中,Fe的质量分数为40.3%,Al的质量分数为59.7%,两相结合生成Fe_(2)Al_(5),此时铝包钢线的性能达到最佳,两相界面结合处的显微硬度(HV)为204,样品电导率为53.23%IACS(国际退火铜标准),密度为4.36 g/cm^(3).

大型ZL205A铝合金舱体铸件铸造工艺研究

以ZL205A厚大舱体铸件为研究对象,针对舱体铸件的特点,开展了铸造工艺方案设计、铸造工艺方案数值仿真计算及熔体处理等技术的研究。研究结果表明:铸件采用差压浇注方法,低热量浇注系统,配合低热量浇注系统使用的冷铁,铸件实现了顺序凝固;铸件经检测,内部质量优良,切取试样力学性能远超过了指标值,各项指标均满足设计要求。

钛合金薄壁弯管熔模铸造工艺研究

通过对钛合金薄壁弯管的结构进行分析,利用三维软件UG对其进行几何建模,采用ProCAST软件对顶注式、雨淋式和底注式三种浇注方案熔模铸造工艺进行了数值模拟,研究对比其在三种浇注方案下铸件的充型及可能出现缺陷的情况。得出在底注式浇注工艺方案下铸件的整体质量最优的结论,并对其进行了试验验证,获得无疏松和夹杂等缺陷的优质铸件。

大型复杂薄壁异形铸件铸造工艺研究

以大型复杂薄壁异形铸件采用ZL101A铝合金为原料,经差压浇注方法、缝隙式浇注系统和合理设置冷铁等工艺生产而成。利用数值模拟仿真、三维激光扫描等先进技术手段完成了铸件的熔炼浇注工艺,获得了尺寸精度高、内部质量好的铸件,并得到了适合异形圆柱铸件浇注成型的优质工艺设计方案。

汽车减速器箱座的铸造工艺与故障诊断研究

本文介绍了一种减速器箱座铸件的铸造工艺方法及常见故障诊断分析。针对此种铸件具有外部结构复杂、壁厚较薄的特点,与几种常用的箱座工艺方法进行了对比,采用了两箱开口朝上的造型工艺。同时为了浇注过程的平稳性,采用底注式浇注系统。便于放置、调节型芯,使铸件质量得到一定保证。此外还对减速器箱座铸造工艺常见故障进行了分析。

一种箱式床身铸件的工艺改进

简述公司生产的一种箱式床身铸件,在生产过程中,铸件上箱面容易出现夹渣、呛气泡、芯撑融合不良等铸造缺陷,导致铸件不良率居高不下。针对这些质量问题,从铸件工艺改进、熔炼浇注系统、参数等方面进行了优化,成功解决了薄壁油箱部位缺陷,保证了产品交付。

铸余渣处理技术研究及应用

分析铸余渣特性及铸余渣处理难点;介绍国内几种铸余渣处理技术及优、缺点。介绍改进转炉渣处理技术用于处理铸余渣提高处理效率。针对一重炼钢厂铸余渣特点提出适用铸余渣处理方案。