5083铝合金半固态浆料流变成形的组织与性能

通过自制的对向式双振动头超声处理装置作用于5083合金半固态浆料并进行流变挤压铸造成形,研究了流变挤压铸造成形工艺和熔体浇注温度等对合金半固态成形制件的组织及力学性能的影响.结果表明,流变成形工艺对合金半固态组织有明显的改善作用,使晶粒更细小、致密、均匀;功率超声和流变挤压铸造能显著提高合金的力学性能;成形制件的组织和力学性能在浇注温度为645℃时最好.     

ZA27合金蜗轮毛坯的成形性与力学性能

对ZA27蜗轮毛坯进行了金属型铸造、挤压铸造和半固态挤压成形试验,研究了在不同工艺条件下,制件的宏观成形性、微观组织形貌和力学性能。结果发现,金属型铸造蜗轮毛坯组织从齿顶到分度圆,均为细密发达的树枝晶;挤压铸件齿顶无树枝状枝晶,齿根的树枝晶晶臂有碎断现象,分度圆枝晶组织破碎圆整痕迹较为明显;半固态挤压件齿顶晶粒组织细化,分布较为均匀,齿根部呈典型的玫瑰状半固态组织形貌,分度圆为细小的等轴晶粒组织。金属型铸造蜗轮齿型成形困难;挤压铸造制备的蜗轮,外观轮廓清晰,齿形饱满;半固态挤压件成形性更加优良。半固态成形件力学性能高于挤压铸造和金属型铸件。     

半固态流变挤压铸造研究现状

半固态挤压铸造是集半固态加工与挤压铸造为一体,利用半固态浆料的流变性能进行充型并在压力作用下凝固成形的一种材料加工新技术.介绍了直接挤压铸造与间接挤压铸造工艺特点,在此基础上着重介绍了铝合金炮弹壳体的半固态流变挤压铸造工艺.     

涂料在半固态钢挤压成形中的应用

在半固态钢挤压铸造成形过程中,主要由模具型腔表面涂层承受高温半固态钢浆料的热冲击,从而降低了浆料对模具的热损伤,提高了模具使用寿命。根据半固态钢挤压铸造涂料的工作环境和特点,通过大量试验对涂料配方、配比、制备工艺、涂敷工艺进行分析研究,确定了诸因素在半固态钢挤压铸造过程中的影响。     

AZ31B镁合金半固态挤压试验研究

对AZ31B镁合金半固态挤压成形管材进行了试验研究,确定了材料加热温度、搅拌时间、搅拌速率、静置时间及半固态浆料浇注温度等成形工艺参数,分析了镁合金管材挤压制件的显微组织与力学性能及其影响因素.结果表明,半固态镁合金挤压制件组织的晶粒细化,小而均匀,尖角钝化,表现出明显的塑性变形特征;制件的抗拉强度、伸长率、断面收缩率、硬度及冲击韧度均有较大幅度的提高.     

轻合金半固态流变挤压铸造的研究进展

半固态挤压铸造是集半固态加工与挤压铸造为一体,利用半固态浆料的流变性能进行浇注充型,并在压力作用下凝固成形的一种材料加工新技术。本文分别介绍了铝合金和镁合金的半固态流变成型工艺的一些方法。介绍了半固态流变挤压铸造的研究进展并对其发展前景进行展望。     

白口铸铁磨球半固态挤压铸造工艺参数设计

半固态挤压铸造是集半固态加工与挤压铸造为一体 ,利用半固态浆料的流变性能进行充型并在压力作用下凝固成形的一种材料成形新技术。作者结合大量的试验研究和理论推导 ,得到半固态挤压铸造基本工艺参数挤压时间、最小挤压力、浇道直径和浇道高度的设计计算公式 ,为半固态挤压铸造设备和铸造工艺的设计及调试提供了基本的参考依据     

半固态成形技术的研究概况与发展前景

半固态成形技术是 ７０年代才发展起来的新的金属成形技术,主要包括半固态轧制、半固态锻造、半固态挤压、流变铸造、触变铸造等工艺类型,和旧有工艺相比优点明显,应用日趋广泛,有着良好的发展前景,被称为２１世纪新兴的金属制造关键技术之一。     

等温热处理对AZ91D半固态挤压铸造成形的影响

研究了等温热处理温度和保温时间等工艺对AZ91D镁合金半固态挤压成形的影响.结果表明半固态等温热处理可以将普通金属型铸造的AZ91D镁合金锭中的枝晶组织转变为球形晶粒组织,并能进行半固态挤压成形.AZ91D镁合金半固态挤压成形所需的最佳工艺条件是加热温度570 ℃左右,保温时间25～35 min,或加热温度580 ℃左右,保温时间10～20 min.     

A356合金连杆半固态挤压铸造工艺参数的优化

基于ProCast2008软件平台,用其自带的非牛顿流体模型Power Law Cut-Off (PLCO)来建立流动模型,对A356合金连杆半固态挤压铸造铸造的充型和凝固过程进行了数值模拟.研究了浇注温度、冲头速度、模具预热温度等主要工艺参数对连杆半固态挤压铸造铸件成形品质的影响规律,获得了连杆半固态挤压铸造铸造的合理工艺参数:浇注温度为576～583℃、模具温度为200～250℃、冲头速度为0.1-0.5 m,s-1.在该工艺参数下进行成形,金属浆料填充平稳,凝固时间较短,挤压铸件缺陷少.     

Semi-solid squeeze casting process of a ZL109 alloy

The structure evolution of the ZL109 alloy in the process of semi-solid squeeze casting and the mechanical properties of the components were investigated. The results show that (1) the eutectic silicon phase in original billets is refined in the low super-heat casting process; (2) the eutectic structure in billets starts to fuse and the crystals of the eutectic silicon phase are refined further and sphericized in the remelting process of billets; (3) in the semi-solid ,squeeze casting process, the sphericity of the α phase and the refining of the silicon phase occur, owing to the friction between solid and liquid; (4) in the process of heat treatment, the eutectic α phase aggregates with the primary α phase and the eutectic silicon pieces aggregate together. The elongation of the semi-solid component after heat treatment rises to 1.42%.     

半固态流变模锻工艺参数对铝合金制件质量的影响

分析半固态流变模锻技术的工艺过程及其特点,指出影响铝合金性能的工艺参数主要有：浇注温度、模锻比压、模锻速度、保压时间、模具温度。根据有关试验结果,归纳出采用半固态流变模锻工艺生产的铝合金可能出现的缺陷有：裂纹、冷隔、型腔充填不满、皮下针孔、疏松、缩孔、气孔。针对这些缺陷提出了相应的预防措施。     

挤压铸造半固态A356铝合金的组织与力学性能

采用低温铸造方法制备A356铝合金半固态坯料.在200 t立式油压机上用挤压铸造方法将A356铝合金半固态浆料挤压成件.研究挤压铸造件的微观组织、力学性能,并与液态挤压铸造件进行比较.结果表明,A356铝合金半固态挤压铸造件组织由球形及椭圆形α-Al晶粒和α+Si共晶成分组成,且制件充型完整、无宏观缩孔、组织致密.在比压48.7 MPa,浇注温度575℃,保压时间3s条件下成形的半固态挤压铸造件的抗拉强度、屈服强度、伸长率分别达到278 MPa、225 MPa、13.2％,相比于在比压48.7 MPa,保压时间3s,710℃液态挤压铸造件性能分别提高了8.6％、8.2％、24.5％.A356铝合金半固态挤压铸造成形件具有较高的综合力学性能.     

半固态A356合金微观组织特征对充型能力的影响

采用电磁搅拌法制备了具有不同微观组织特征的半固态A356合金浆料,用图像分析软件对浇注前浆料金相试样的初生相微观组织特征进行了测定,利用间接挤压铸造方法铸造阿基米德螺旋线试样,以挤压成形后的螺旋线试样长度衡量充型能力,通过多元回归,建立了半固态A356合金初生相微观组织特征与充型长度之间的数学表达式。结果表明:半固态浆料充型能力不仅与初生相微观组织特征参数有关,微观组织特征参数的交互作用对充型能力的影响也较大。利用该表达式可以对半固态浆料充型能力进行预测,进而指导半固态浆料制备参数设计、间接挤压铸造工艺设计和缺陷预测。     

Microstructure characteristics and mechanical properties of rheoformed wrought aluminum alloy 2024

The microstructure characteristics and mechanical properties of 2024 wrought aluminum alloy produced by a new rheoforming technique under as-cast and optimized heat treatment conditions were investigated. The present rheoforming combined the independently developed rheocasting process, named as LSPSF (low superheat pouring with a shear field) process, and the existing squeeze casting process. The experimental results show that LSPSF can be used to prepare sound semi-solid slurry within 25s to fully meet the production rate of squeeze casting. The primary α (Al) presents in mean equivalent diameter of 69μm and shape factor of 0.76, and features zero-entrapped eutectics. Compared with conventional squeeze casting, the present LSPSF rheoforming can improve the microstructures and mechanical properties. An optimized heat treatment results in substantial reduction of microsegregation and significant improvement of mechanical properties, such as yield strength of 321MPa, ultimate tensile strength of 428MPa and elongation of 12%.     

Effect of the gate geometry and the injection speed on the flow behaviors of a semi-solid A356 Al alloy

The effects of the viscosity, gate speed, and gate geometry on the flow behaviors of Al alloys in molten and semi-solid states were studied by direct observations of the flow patterns during die filling. Two different fluids, thixotropic fluid (semi-solid Al alloy) and Newtonian fluid (molten Al alloy), were chosen as the model fluids for monitoring the differences in flow patterns during die filling. High-speed photography was employed to record the real time flow patterns. Qualitative assessments on the critical gate speed were made based on the experimental results. The experimental results were also compared with results predicted based on the Reynolds number. Although the critical gate speed varies depending on the gate geometry, it is less than ∼2.5 m/sec in semi-solid forming, while it ranges from 0.3∼0.5 m/sec in squeeze casting.     

Research and Applications of Semi-solid Processing

Since it was pioneered by Flemings and otherresearchers [11, the semi-solid metal processingtechnique has been widely stUdied in the world.Especially in the past decade, SSM as a newproduct forming technique has been rapidly developed and put into commercial applications[2, 31. In recent years, with the development ofthe ado-industry of China, a lot of researchwork on SSM has been done, including the preparation of slumes, reheating and thixoforming[Al6]; moreover, great achievements have …     

热处理对半固态A356铝合金挤压铸件组织与性能的影响

将低温浇注制备的半固态A356铝合金坯料加热至半固态浇注、挤压成形。采用正交试验法研究了固溶、时效对半固态A356铝合金挤压铸件组织与力学性能的影响。结果表明,时效时间对抗拉强度、屈服强度、伸长率影响最大,且都是随着时效时间增长先上升后下降;试验6获得较好的综合力学性能,其抗拉强度、屈服强度、伸长率分别为340 MPa、325 MPa、9.56%。     

镁合金半固态铸造的现状及发展前景

介绍了镁合金半固态铸造的三种工艺和镁合金半固态组织制备方法的研究与应用现状.展望了镁合金半固态铸造技术在我国的发展前景.