AZ80镁合金半固态挤压铸造成形件质量控制研究

以AZ80镁合金为研究材料,针对半固态挤压成形中出现的表面皱皮、冷隔以及裂纹等铸件缺陷进行了分析,并提出了相应的改进措施.     

AZ31镁合金型材宽展挤压工艺参数研究

在某镁业有限公司的挤压车间进行了AZ31镁合金型材宽展挤压温度、挤压速度和变形程度等工艺参数的研究,在某铝业有限公司进行了AZ31镁合金型材宽展挤压。通过对挤压温度、挤压速度和变形程度进行控制,有效地提高了出品速度和成品率,对于镁合金型材宽展挤压技术具有实践意义。     

挤压铸造制备半固态AZ61镁合金的组织演变及力学性能(英文)

采用挤压铸造后直接二次重熔的方法制备半固态AZ61镁合金。首先通过挤压铸造预成形铸态AZ61镁合金,以获得细小的枝晶;然后在半固态区间进行二次重熔,细小的枝晶演变成球状晶,完全球化的晶粒被液相均匀包裹。研究结果表明:通过挤压铸造预成形的铸态AZ61镁合金与传统铸造预成形的铸态AZ61镁合金相比,在相同的二次重熔条件下,挤压铸造预成形的铸态AZ61镁合金获得更细小的半固态组织。此外,挤压铸造加上二次重熔触变成形的AZ61镁合金,力学性能优于传统铸造后二次重熔触变成形的AZ61镁合金。     

AZ81镁合金挤压铸造铸件的缺陷分析

以Mg-Al系合金AZ81为研究对象,采用挤压铸造工艺进行汽车转向控制臂铸件的生产.针对试生产过程中铸件产生的各类缺陷,从其形成机理和影响因素方面进行分析,研究挤压铸造各工艺参数对AZ81镁合金的铸造组织的影响.     

挤压比对AZ80镁合金组织及性能的影响

在温度为390℃时,对AZ80镁合金在工业用压力机上采用15、30、45、60和75五个挤压比进行正挤压,并对不同挤压试样进行研究分析.结果表明:随挤压比的增加,即变形量的增加,在变形过程中新晶粒所占体积分数越来越大,且在一定条件下动态再结晶可以重复进行,因此使晶粒得到明显细化,有效提高了合金综合性能.随挤压比升高,强度有升高趋势,其抗拉强度在挤压比为60时达390MPa,伸长率达11%.     

BP神经网络在AZ91D镁合金挤压铸造工艺中的应用

采用BP人工神经网络建立AZ91D镁合金力学性能与挤压铸造工艺参数的关系模型,研究并分析了工艺参数对合金力学性能的影响规律.结果表明:比压对合金力学性能影响最强,浇注温度次之,保压时间最弱.在浇注温度680℃、比压200 MPa、保压时间25 s、模具温度280℃条件下可使合金获得良好综合性能.BP网络模型预测的准确率最高为96％,具有良好的可靠性和推广价值,对挤压铸造AZ91D镁合金生产具有实践指导和理论借鉴意义.     

挤压铸造AZ91D合金工艺参数的研究

为了提高挤压铸造AZ91D合金制件的质最,在实验室条件下,运用多因素正交实验,采用不同工艺参数对该镁合金的成形性进行了研究.试样经力学性能测试和显微组织分析,结果表明:浇注温度为730℃、挤压压力为100MPa、保压时间为25s时所得试样晶粒细小,析出了更多的第二强化相β(Al_(12)Mg_(17)),试样的综合力学性能最好.     

汽车用AZ80合金的挤压铸造工艺及组织性能研究

对汽车用AZ80合金进行挤压铸造,研究浇注温度、挤压压力、模具预热温度和保压时间对AZ80合金组织和力学性能的影响,并分析其作用机理。结果表明,AZ80合金的适宜挤压铸造工艺为:浇注温度700℃、挤压压力90MPa、模具预热温度为250℃、保压时间为25 s,在此工艺下的AZ80合金可以取得较好的强度和塑性结合;AZ80合金力学性能的提高,主要与挤压工艺参数调控合金晶粒大小和显微缺陷有关。     

挤压铸造AZ81镁合金均匀化热处理工艺研究

为改善挤压铸造AZ81镁合金组织的不均匀性,对铸态试样进行均匀化热处理。采用金相显微镜、X射线衍射仪和扫描电镜对AZ81镁合金的组织与性能进行分析。结果表明:经400℃、8h均匀化处理后,AZ81合金有效地消除了枝晶偏析,改善了材料的组织状态;合金硬度由HRE73.72下降到HRE57.68,屈服强度由130MPa增加到138MPa,抗拉强度由226MPa增加到258MPa,伸长率则由7.6%增加到13.6%;试样的室温拉伸断口均为准解理断裂,经均匀化处理后断裂方式由沿晶界的脆性断裂转变为韧性穿晶断裂。     

ZA27挤压铸造工艺参数的优化

基于人工神经网络建立ZA27合金挤压铸造工艺参数与力学性能关系模型，采用模拟退火算法对ZA27挤压铸造工艺进行多指标优化。结果表明：当比压为40MPa、铸型温度在230～240℃、浇注温度在540～550℃、保压时间在50s左右时，ZA27合金具有较高的综合力学性能。     

Microstructure character of AZ80 magnesium alloy ingots cast under electromagnetic vibration

Microstructure evolutions of an AZ80 magnesium alloy ingot with 300 mm in diameter cast with and without the electromagnetic vibration was investigated. The microstructures of the ingot cast with the conventional DC exhibited relatively fine dendritic grains at the surface area, but coarse dendritic grains at the 1/2 radius and large equiaxed dendritic grains at the center. However, under the electromagnetic vibration casting condition, the microstructures of the ingot is significantly refined, especially those at the surface and at the center.     

Corrosion properties of plastically deformed AZ80 magnesium alloy

AZ80 magnesium alloys were deformed at 200,250,300,350 and 400℃ with different deformation degree of 50%,75%, 83%,87%and 90%,respectively.The corrosion properties of different deformed AZ80 samples were studied by galvanic test in 3.5%NaCl solution.The results show that plastic deformation could improve the corrosion resistance of AZ80 alloy;and the corrosion rate of AZ80 deformed at 250℃ with the deformation degree of 83%was the lowest,which was 33%of the as-cast AZ80 alloy.Further studies of the microstructure show that the refined grain size and continuously distribution ofβphase around the grain boundary did have a positive effect on the improvement of corrosion resistance of AZ80 alloys.For AZ80 alloys,the smaller the grain size is,the more homogeneous the structure is,and the better the corrosion resistance is.     

Fracture behaviors of AZ80 magnesium alloy during multiple forging processes

1 Introduction Pure magnesium and magnesium alloys are the lowest density metals used as structural materials and have excellent specific strength and stiffness, machinability, dimensional stability, and excellent recycling capability. They are, therefor…     

Study on fluidity of squeeze cast AZ91D magnesium alloy with different wall thicknesses

Rectangular cross-section specimens with different section thicknesses were prepared to study the infl uences of pouring temperature, mould temperature and squeeze velocity on the fl uidity of squeeze cast AZ91D magnesium alloy by means of orthogonal test design method. The results show that pouring temperature, mould temperature and squeeze velocity can significantly affect the fluidity of magnesium alloy specimens with wall thickness no more than 4 mm, and the pouring temperature is the most infl uential factor on the fl uidity of specimens with wall thickness of 1, 2 and 3 mm, while mould temperature is the one for specimens with wall thickness of 4 mm. Increasing pouring temperature between 700 °C and 750 °C is benefi cial to the fl uidity of AZ91D magnesium alloy, and increasing mould temperature signifi cantly enhances the fi lling ability of thick(3 and 4 mm) section castings. The fl uidity of squeeze cast magnesium alloy increases with the increase of wall thickness. It is not recommended to produce magnesium alloy casting with wall thickness of smaller than 3 mm by squeeze cast process due to the poor fl uidity. The software DPS was used to generate the regression model, and linear regression equations of the fl uidity of squeeze cast AZ91D with different wall thicknesses are obtained using the test results.     

Corrosion fatigue behavior of the high-strength magnesium alloy AZ 80

The fatigue performance of the high-strength magnesium alloy AZ 80 is studied in air as well as in aqueous 0.5 and 3.5% NaCl solutions. The effect of mechanical surface treatments, specifically mechanical polishing, shot peening, and roller burnishing on the S-N curves, is investigated using an electropolished surface as a reference. While mechanical polishing as well as shot peening improves fatigue performance in air, no improvement is observed in NaCl solutions. However, roller burnishing, which combines a smooth surface finish with residual compressive stresses in sufficient depths, leads to outstanding fatigue performance even in 3.5% NaCl solution.     

热处理对AZ80镁合金结构及性能的影响

利用环境扫描电镜（ESEM）和透射电镜（TEM）研究了时效温度对AZ80镁合金析出相的影响,测定了析出相／基体的位向关系,分析了不同析出相的析出机理及其对合金性能的影响．实验中观察到β-Mg17Al12析出相的一种新的析出方式一颗粒状卢相沿晶界及孪晶处形核、生长．AZ80镁合金高温（310℃）时效时,析出相为连续析出,呈菱形片状或颗粒状．其中前者在晶内均匀形核生长,与基体的基面平行,对合金性能有一定强化作用;而后者分布于晶界,它的出现大大降低了合金性能．时效温度降低（〈250℃）,将出现不连续析出相,呈片层状,其片层与基体基面平行或垂直,在晶界形核并向晶内生长,随着不连续析出相的生长,将推动晶界向前移动,不连续析出相对合金的性能强化效果较大．     

AZ80镁合金的高温拉伸变形行为

采用拉伸至断裂实验,在温度为300、350、400和450℃,应变率分别为10~（-2）和10~（-3）S~（-1）条件下,研究AZ80镁合金的拉伸行为。并采用变化应变率拉伸实验在5×10弓至2×10~（-2）S~（-1）的应变率范围内进行变形机制研究。结果表明：该材料在400和450℃下具有超过100％的高伸长率,其应力指数为4．29,变形激活能为149．60kJ／mol。初始细晶粒在均匀变形区的高温变形中较为稳定,其变形机制为晶界滑移和位错攀移蠕变的竞争机制。基于该机制所建立的数学模型的模拟结果与实验数据吻合。     

基于层宽控制的AZ91镁合金TIG电弧增材工艺优化

针对镁合金电弧增材制造表面成形质量控制的难题,通过Design-Expert软件对AZ91镁合金TIG电弧增材的电流、送丝速度、增材速度等工艺参数和熔覆层层宽之间进行建模,探索了各工艺参数对增材层宽的影响规律,并利用增材主要工艺参数和尺寸的数学模型优化了增材电流,根据电流优化值来控制直壁构件层宽。结果表明,对层宽影响最大的是增材电流,其次是增材速度,影响最小的是送丝速度;采用优化后的工艺增材制备的单道多层构件自上至下的层宽波动起伏小,层宽偏差值由4.54 mm减小到0.94 mm,提高了AZ91镁合金增材成形质量。创新点： (1)采用响应面法分析了工艺参数对AZ91镁合金TIG电弧增材层宽的影响规律,建立了二者之间的关系模型。(2)通过优化电流参数实现了AZ91镁合金单道多层增材样件层宽控制,提高了增材样件的成形质量。