热挤压工艺对AZ31镁合金组织性能的影响

为满足更多的结构件的应用需求，采用热挤压T艺对AZ31镁合金进行变形，研究了挤压比和挤压温度对AZ31合金显微组织和力学性能的影响．结果表明：挤压可以显著细化AZ31合金显微组织．且挤压比越大，晶粒尺寸越细小．力学性能得到较大提高；挤压温度也影响AZ31镁合金组织性能，在实验中发现，在350℃时AZ31镁合金组织均匀，力学性能较为良好。     

热挤压工艺对AZ31镁合金组织与力学性能的影响

在不同挤压条件下对AZ31镁合金进行了热挤压试验,并对挤压前后材料组织与力学性能的变化进行了分析.研究结果表明,AZ31镁合金热挤压时发生了动态再结晶,材料组织比铸态时细化,力学性能大幅度提高;AZ31镁合金挤压后的组织及力学性能受挤压温度及冷却方式影响,在本试验范围内,AZ31镁合金在623 K挤压后空冷得到的组织均匀细小,力学性能良好.     

轧制和退火对AZ31合金组织与性能的影响

以普通轧制和等径角轧制态AZ31合金为实验对象,研究了退火温度和退火时间对AZ31合金组织与成形性能的影响,并分析了其作用机理。结果表明,普通轧制态AZ31合金组织中可见大小不均的等轴晶粒,同时部分尺寸较大的晶粒内还有少量挛晶组织存在,而等径角轧制AZ31合金中晶粒尺寸与普通轧制态AZ31合金相当,但是挛晶数量明显增多;随着退火温度的升高和退火时间的延长,普通轧制和等径角轧制AZ31合金发生了初次再结晶和二次再结晶,晶粒趋于均匀、等轴化,并有逐渐粗化的趋势;退火温度为200℃和退火时间15 min以上的AZ31合金中的挛晶基本消失;退火处理后普通轧制和横向等径角轧制AZ31合金的断后伸长率和应变硬化指数增大,而纵向等径角轧制AZ31合金的应变硬化指数变化不大。     

机械研磨处理对AZ31合金组织与性能的影响

采用表面机械研磨的方法对变形AZ31合金板材进行了表面改性处理,对比分析了原始AZ31合金与经过机械研磨的AZ31合金的显微组织、硬度、力学性能、耐磨性能和摩擦磨损形貌。结果表明,经过表面机械研磨处理后,AZ31合金的抗拉强度和屈服强度都得到明显提高,而断后伸长率却略有降低;随着载荷的增加,原始AZ31合金和经过表面机械研磨处理后的AZ31合金的摩擦系数都呈现逐渐降低的趋势;在相同的载荷作用下,经过表面机械研磨的AZ31合金的摩擦系数都要小于原始AZ31合金;在载荷小于30 N时,经过表面机械研磨的AZ31合金的磨损率都要小于原始AZ31合金,而在载荷为50 N时经过表面机械研磨的AZ31合金的磨损率要高于原始AZ31合金。     

挤压工艺对AZ31镁合金组织和性能的影响

研究了挤压温度和挤压速率对AZ31镁合金显微组织、耐腐蚀性能和力学性能的影响。结果表明,通过300℃下的热挤压变形,AZ31合金发生动态再结晶,合金组织比铸态时细化,耐腐蚀性能和力学性能明显提高;AZ31镁合金挤压后的组织及力学性能受挤压温度及挤压速率的影响,在本试验范围内,AZ31镁合金经过挤压温度为300℃、挤压速率为6.0 mm/s的挤压变形后得到的组织均匀细小,耐腐蚀性能和力学性能良好。     

轧后深冷处理工艺对AZ31镁合金板材组织和力学性能的影响

为了改善传统热轧AZ31镁合金板材的微观组织,提升其综合力学性能,将AZ31镁合金板材经360℃热轧后,采用不同时间液氮浸泡进行深冷处理,研究不同深冷时间处理对热轧AZ31镁合金显微组织和力学性能的影响.结果表明:经深冷处理后,热轧AZ31镁合金中析出第二相,同时合金内部晶粒尺寸得到细化,导致孪晶产生.AZ31镁合金热...     

Zn-Mg钎料钎焊镁合金AZ31B的显微组织与力学性能

为了连接变形镁合金AZ31B母材,以Zn-Mg钎料对变形镁合金AZ31B进行了高频感应钎焊,研究了Zn-Mg钎料的显微组织、钎焊接头的显微组织及力学性能.采用X射线衍射仪、扫描电镜、X射线能谱分析仪等分析了钎焊接头的界面组织及钎缝物相,测试了钎焊接头的强度及界面组织的显微硬度.结果表明,Zn-Mg钎料与母材AZ31B发...     

表面机械研磨对AZ31合金组织与性能的影响

采用机械研磨的方法对AZ31合金进行了表面纳米化处理,研究了机械研磨时间对AZ31合金显微组织、显微硬度和拉伸力学性能的影响。结果表明,随着表面机械研磨时间的延长,AZ31合金梯度纳米结构层厚度呈现先增加而后降低再上升趋势。表面机械研磨4和15 min时,梯度纳米结构层达到90μm以上;表面机械研磨处理可以在AZ31合金心部获得一定体积分数的孪晶组织;表面机械研磨处理可以使AZ31合金的抗拉强度、屈服强度均呈现出不同程度的增加,而断后伸长率有所降低;AZ31合金适宜的表面机械研磨时间为4 min。     

镁合金薄板焊接性能研究

采用钨极交流氩弧焊焊接方法制备了0.8 mm厚的AZ31和AZ80镁合金拼焊板,分析了AZ31和AZ80镁合金拼焊板的焊接性能,确定了钨极交流氩弧焊接工艺参数.研究结果表明,AZ31镁合金焊缝处的晶粒为等轴晶,热影响区组织是树枝状晶.AZ31-AZ80拼焊板的焊缝处缺陷主要是气孔和热裂纹.焊缝性能与焊接母材的性能相当.     

AZ31合金板材的显微组织、拉伸性能与冲压工艺探索

研究了AZ31合金轧制过程中的组织演变及与室温拉伸性能的对应规律,探索了AZ31合金手机壳和笔记本电脑壳的冲压工艺.结果表明,经过多道次的轧制变形后,均匀化态的AZ31合金组织发生了动态再结晶,晶粒明显细化且呈等轴态,平均尺寸小于20 μm.厚度为2 mm和0.6 mm的AZ31合金板材室温拉伸强度对变形方向较敏感,延伸率也随着取样方向有所改变.在100～350℃下,利用厚度0.6 mm AZ31合金板材冲压出手机外壳和笔记本电脑外壳.经过EBSD分析表明,基面和棱柱面织构的存在导致了AZ31合金板材力学性能的各向异性.     

Thermal Stability of Nanocrystalline AZ31 Magnesium Alloy Fabricated by Surface Mechanical Attrition Treatment

A nanocrystalline layer(NL) was fabricated on the surface of AZ31 magnesium(Mg) alloy sheet by surface mechanical attrition treatment(SMAT). The microstructure of the Mg alloy was characterized by optical microscopy,X-ray diffraction and microhardness test. The results showed that both the microstructure and microhardness of AZ31 Mg alloy sheet after SMAT revealed a gradient distribution along depth from surface to center. The thermal stability of the NL was investigated through characterizing the microstructure evolution during the post-isothermal annealing treatment within the temperature range from 150 to 250 ℃. The NL exhibits a certain degree of thermal stability below 150 ℃, while it disappears quickly when annealing at the temperature range of 200–250 ℃. The grain growth kinetics of the nanocrystalline of AZ31 Mg alloy induced by SMAT was investigated. The activation energy of nanocrystalline AZ31 Mg alloy was obtained with a value of 92.8 k J/mol.     

Effect of Vanadium Nitride (VN) Particles on Microstructure and Mechanical Properties of Extruded AZ31 Mg Alloy

The effect of vanadium nitride (VN) particles additives on microstructure and mechanical properties of the extruded AZ31 Mg alloy was systematically investigated. The experimental results revealed that the addition of 0.5 wt% VN decreased the average grain size of AZ31 Mg alloy from 6.4 to 4.9 µm. With the increase in VN content, the refining effect would weaken because excessive VN particles would negatively affect the dynamic recrystallization process of the alloys. The scanning electron microscopy and energy-dispersive spectroscopy indicated that AlN, VN and Al-V-N particles with different morphologies were distributed in the streamline along the extrusion direction during the extrusion process. The mechanical properties of AZ31 Mg alloy vary with the addition of VN. The extruded AZ31 + 0.5 wt% VN Mg alloy possesses an excellent combination of high strength and ductility. The yield strength and ultimate tensile strength of the extruded AZ31 + 0.5 wt% VN Mg alloy were increased without sacrificing ductility. This is mainly due to the grain refinement caused by double-heterogeneous nucleation particles. With a further increase in VN content, the presence of excessive VN particles increases the stress concentration, and the initiation source of microcracks in the alloy during alloy deformation makes the cracks more easily propagated and results in a decrease in the ductility of the extruded alloy.     

Nd对AZ31镁合金微观组织与力学性能的影响

研究了Nd对AZ31镁合金微观组织和力学性能的影响.结果表明:Nd在AZ31合金中的吸收率达95%,Nd加入AZ31合金中形成了Al2Nd和Mg12Nd金属间化合物,Nd使合金的平均晶粒尺寸减小,力学性能提高.含Nd的AZ31合金铸态抗拉强度、屈服强度和伸长率值分别为245 Mpa、171 Mpa和9%.     

大塑性变形镁合金的晶粒细化(英文)

采用电子背散射技术(EBSD)定量研究AZ31镁合金在225~400°C往复挤压大变形过程中的晶粒细化。结果表明:在225°C往复挤压3道次即获得了超细晶AZ31镁合金。随着变形温度的降低,变形组织的平均位相差和大角度晶界的比例逐渐增加。在3道次的AZ31组织中,只发现少量的{1 012}孪晶,位错滑移是主要的变形机制。施密特因子计算表明,在225~350°C变形时,锥面滑移系{1011}1 120被大量激活。而在400°C变形时,基面滑移系{0001}1 120被大量激活。亚晶界的详细分析为连续动态再结晶在镁合金大变形过程中晶粒细化的重要作用提供了直接的证据。     

Evaluation of corrosion resistance of multipass friction stir processed AZ31 magnesium alloy

Multipass friction stir processing (FSP) is an effective method to produce a homogeneous microstructure and enhance the mechanical properties of magnesium (Mg) alloys. However, few studies have concentrated on the variation of corrosion resistance of Mg alloys during multipass FSP. Electrochemical alternating current (AC) impedance, polarization behavior, hydrogen evolution, and corrosion morphology were used to investigate the effects of subsequent passes on the corrosion resistance of FSP AZ31 plates. A quasi‐in‐situ observation of the growth of corrosion products was carried out to further study the corrosion behaviors of FSP AZ31 alloy. It is found that subsequent passes could further reduce the grain size of FSP AZ31 alloy and result in an increase in the hardness compared with the first pass. Moreover, subsequent passes are beneficial to the improvement in the corrosion resistance of AZ31 alloy. Pitting corrosion occurs in FSP AZ31 plates, which has not changed after subsequent passes.     

Characterization of the corrosion performances of as-cast Mg–Al and Mg–Zn magnesium alloys with microarc oxidation coatings

In the present study, corrosion-protective microarc oxidation (MAO) coatings were prepared on AZ31B, AZ80, and ZK60 cast magnesium alloy substrates in an alkaline silicate electrolyte. The corrosion performances of the uncoated and MAO-coated alloys were investigated using electrochemical and salt spray chamber corrosion tests. The microstructure characterization and experimental results show that among the three alloys studied, the ZK60 Mg alloy exhibited the best and AZ31B the least corrosion resistance under the salt spray conditions. The MAO coating provided robust corrosion protection of the Mg substrates and resulted in a significant decrease in the corrosion rate of the alloys by 3–4 orders of magnitude. The MAO coating on ZK60 alloy showed better corrosion protectiveness than that on the AZ series alloys due to the incorporation of different alloying elements in the coating, especially the Zn and Al elements, which are from the Mg substrate. The corrosion performances and mechanisms of the uncoated and MAO-coated Mg alloys are interpreted in terms of the microstructure and phase/chemical compositions of both the substrates and coatings.     

镁铝轻质复合板多层挤压复合工艺

采用挤压工艺对AZ31镁合金板和6061铝合金板进行多层挤压复合,结合扫描电镜、能谱分析仪、金相显微镜、EBSD以及万能拉伸试验机等分析手段,研究了不同坯料层数对AZ31/6061复合板的微观组织及力学性能的影响。实验结果表明:复合板镁合金侧中存在大量的细小再结晶晶粒和少量变形组织,复合板铝合金侧的晶粒呈现典型的带状结构,且周围有大量细小再结晶晶粒生成;此外,复合板中Mg/Al界面具有良好的冶金结合,且有不同厚度的界面反应层生成,其中P1板的界面反应层以Mg_2Al_3为主,P2板靠近镁合金侧有Mg_(17)Al_(12)生成,靠近铝合金层有Mg_2Al_3生成。     

Environmentally friendly anodization on AZ31 magnesium alloy

A novel anodization which is environmentally friendly,low voltage and low energy consumption was developed to improve corrosion resistance of AZ31 magnesium alloy.The corrosion resistance of the anodic films was studied by electrochemical impcdance spectroscopy(EIS) and potentiodynamic polarization techniques.The microstructure and compositions of films were examined by SEM,XPS and XRD.A new kind of organic additive used in the electrolyte is friendly to the environment.The compact, intact and uniform co...     

Mg3Sb2含量对Al-Mg3Sb2复相涂层耐磨性的影响

目的研究Mg_3Sb_2含量对Al-Mg_3Sb_2复相涂层的组织、硬度和摩擦学性能的影响,对比分析AZ31B镁合金基体、纯Al涂层和添加不同含量的Mg_3Sb_2之后涂层性能的差异。方法通过火焰喷涂技术在AZ31B镁合金表面制备了Al-Mg_3Sb_2复相涂层。利用扫描电镜(SEM)观察了涂层的截面形貌,利用X射线衍射仪(XRD)分析了涂层的物相组成。通过显微硬度计测试了AZ31B和涂层的硬度,通过摩擦磨损试验仪测试了AZ31B和涂层的摩擦学性能,并通过超景深三维显微镜测试了试样的磨痕宽度、深度及磨损体积。结果经火焰喷涂后可得到组织致密的复相涂层,涂层中的物相主要为Mg_3Sb_2和Al。涂层的平均硬度随Mg_3Sb_2含量的增加而增加,最高可达334.2HV0.025,是AZ31B的4.14倍。摩擦磨损试验中,涂层的摩擦系数随着Mg_3Sb_2含量的增加而减小,但都大于AZ31B的摩擦系数;涂层的磨损率随着Mg_3Sb_2含量的增加而减小,60%Mg_3Sb_2和80%Mg_3Sb_2涂层的磨损率小于AZ31B的磨损率,其他涂层的磨损率大于AZ31B的磨损率,80%Mg_3Sb_2涂层的耐磨性最好,比AZ31B下降了63.26%。随着Mg_3Sb_2含量的增加,Al-Mg_3Sb_2复相涂层的磨痕表面犁沟逐渐变浅并消失。结论 Mg_3Sb_2的加入可以提高涂层的硬度,随着其含量的增加,涂层的耐磨性逐渐提高。     

等通道角轧制对汽车车身用轻质镁合金板微观组织与力学性能的影响

采用等通道角轧制工艺(ECAR)对AZ31镁合金板进行轧制变形,结合光学显微镜、EBSD、杯突实验机和拉伸实验机等检测方法,研究了不同ECAR工艺对镁合金板微观组织及力学性能的影响。实验结果表明,AZ31镁合金板经ECAR工艺处理后,板材的平均晶粒尺寸出现下降,且板材的基面织构出现了明显地降低,由母材的8.187降低为4.537。此外,镁合金板材的综合性能得到显著提高,板材的杯突值由母材的2.72 mm增加到4.22 mm,n值由母材的0.27增加到0.46,抗拉强度由母材的275 MPa增加到294 MPa。综上所述,等通道角轧制工艺可以有效细化镁合金板材的微观组织,提高镁合金板材的综合力学性能。