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1.
镁合金塑性变形机制   总被引:29,自引:0,他引:29  
针对不同晶粒尺寸的镁合金AZ31及添加稀土Ce或Nd的AZ31Ce/AZ31Nd的轧制变形行为,探讨了滑移、孪生和晶界滑动三种变形机制在镁合金塑性变形过程中的作用.结果表明:多种变形机制共同作用可提高镁合金在热变形时的塑性变形能力;合金热变形及再结晶退火后,在平均晶粒尺寸为50 μm以上的大晶粒中,变形机制以滑移和孪生为主,位错运动和增殖会使位错在变形过程中互相缠结、钉扎以及受晶界的阻碍而终止运动;孪生容易发生在不利于滑移的晶粒中促进塑性变形;在5~20μm的小晶粒中,晶界滑动机制发挥了重要作用,它可以协调大尺寸晶粒的变形而对提高镁合金变形能力起有益的补充作用.  相似文献   

2.
沿热轧退火态AZ31镁合金轧制方向进行室温动态塑性变形,采用场发射扫描电子显微镜研究{10ī2}孪生的变体类型及结构特征。结果表明:在{10ī2}孪生机制主导塑性变形的初级阶段(ε8%),AZ31镁合金中大部分晶粒内部仅产生一种{10ī2}孪生变体或变体对,所以孪晶结构呈彼此平行状,将晶粒分割成片层组织;这种片层组织的厚度随着应变量的增加而减小,从5.55μm减小到2.49μm;少数晶粒形核产生不同的{10ī2}孪生变体,且这种晶粒的数量随着塑性变形量的增大而增加;当ε8%,孪生体积分数接近饱和,位错滑移成为镁合金主要的变形机制。  相似文献   

3.
研究了铸态AZ31镁合金在温度为250~425℃、变形量为10%~40%、应变速率为0.01 s-1的条件下的热压缩时动态再结晶的变化规律,分析了流变应力与变形程度的关系。结果表明:铸态AZ31镁合金在应变速率为0.01 s-1的条件下进行热压缩变形,变形程度达到40%时,材料会发生断裂;当应变速率和变形温度一定时,流变应力随变形程度的增大不断增加,在达到峰值后逐渐降低,表现出明显的动态再结晶的特征;且随变形程度的增大,动态再结晶晶粒越来越多。  相似文献   

4.
大晶粒AZ91镁合金的超塑变形行为   总被引:3,自引:0,他引:3  
研究了晶粒尺寸为 85 μm的大晶粒AZ91镁合金在高温下的超塑拉伸变形行为。结果表明 ,大晶粒AZ91合金能在高温下获得超塑性。在 35 0℃下 ,应变速率为 3× 10 - 4s- 1 拉伸时 ,最大伸长率达2 2 8%。 30 0℃下 4 0 %的预应变可以改善合金在更高温度下的超塑性能。在超塑拉伸变形初期 ,动态再结晶细化了合金的晶粒 ,呈现出细晶超塑的特征 ;随着应变量的增加 ,合金的晶粒长大趋势不明显。大晶粒AZ91合金的超塑性变形机制是晶界滑移控制下的孔洞连接协调机制。  相似文献   

5.
采用背散射电子衍射技术(EBSP)分析AZ91镁合金在热压缩变形过程中的流变行为及组织演变特征。研究表明,该合金在热压缩实验中通过动态再结晶过程细化基体晶粒。随应变速率降低,稳态组织的平均晶粒尺寸增大,大尺寸晶粒比例和大边数晶粒比例增加。流变曲线的峰值应力随Zener-Hollomon参数的增大而增大。  相似文献   

6.
等通道角挤压变形AZ31镁合金的变形行为   总被引:6,自引:2,他引:4  
研究挤压态和等通道角挤压(EcAE)态AZ31镁合金的变形行为与微观组织的相关性.结果表明,ECAE态AZ31镁合金的室温拉伸屈服强度与晶粒尺寸之间表现出反Hall-Petch关系,且拉压不对称性明显减弱;在室温压缩时表现出应变速率敏感性,并随变形温度升高,应变速率敏感性因子变大.挤压态合金的晶粒度为20 μm,具有典型的挤压丝织构,主要变形方式为基面位错滑移和孪生,导致了合金中明显的拉压不对称性.ECAE态合金平均品粒尺寸约为2μm,织构相对随机化,导致合金压缩时孪生比率明显下降,其他变形模式比率增加,提高了变形抗力,降低了拉压不对称性.ECAE态AZ31镁合金压缩的激活能接近其晶界扩散激活能,晶界滑移在一定程度上导致了合金的反Hall-Peteh关系的出现以及应变速率敏感性的增强.  相似文献   

7.
在Gleeble-1500D热模拟机上进行热压缩试验,研究了变形温度为320~440℃、应变速率为0.001~1 s<'-1>,最大变形程度为60%的条件下挤压态AZ81镁合金的高温流变行为.结果表明,采用加工理论分析材料的高温变形行为能准确反映出材料在不同变形条件下的组织演变规律.根据材料动态模型计算了挤压态AZ81合金的热加工图,结合显微组织观察结果分析了挤压态AZ81镁合金的热加工塑性变形性能,在变形温度320~440℃、应变速率0.001~1 s<'-1>,最大变形程度为60%的条件下,失稳判据ξ(ε)>0,说明AZ81镁合金在该条件下的塑性变形性能良好.热加工温度380~400℃、应变速率0.01~0.1 s<'-1>为最佳热加工工艺参数区.  相似文献   

8.
AZ80合金高温变形行为及加工图   总被引:6,自引:0,他引:6  
为实现AZ80合金塑性成形的数值模拟和制定其合理的热加工工艺,利用热模拟机对AZ80合金进行不同变形温度和应变速率的高温压缩变形行为研究.结果表明:AZ80合金的高温流动应力-应变曲线主要以动态回复和动态再结晶软化机制为特征,峰值应力随变形温度的降低或应变速率的升高而增加;在真应力-应变曲线基础上,建立的AZ80合金高温变形的本构模型较好地表征其高温流变特性,模型计算精度高;同时,利用建立的AZ80合金的DMM加工图分析其变形机制和失稳机制,从提高零件力学性能角度考虑,可以优先选择变形温度为300~350 ℃、应变速率为0.001~0.01 s-1的工艺参数.  相似文献   

9.
铸态AZ61镁合金热压缩变形组织变化   总被引:2,自引:1,他引:1  
利用Gleeble-1500对铸态AZ61镁合金在变形温度200~500℃,应变速率0.001~1s-1的条件下进行压缩变形;利用显微结构分析和硬度测试等研究不同变形条件下AZ61镁合金的组织和性能,引用Z值(Zener-Hollomon系数)研究温度和应变速率对AZ61镁合金组织的影响,建立再结晶晶粒尺寸与Z值之间的关系。结果表明:铸态AZ61镁合金在热变形时表现出动态再结晶特征,随温度上升,再结晶容易发生且峰值应力降低,再结晶晶粒尺寸随温度升高而增大;随应变速率上升,峰值应力增大且峰值应力对应的应变量增大,再结晶晶粒尺寸减小;硬度大小的变化也与动态再结晶密切相关。  相似文献   

10.
工业态AZ31镁合金的超塑性变形行为   总被引:35,自引:2,他引:33  
研究了工业态AZ31镁合金在温度 6 2 3~ 72 3K和应变速率 1× 10 -5~ 1× 10 -3 s-1范围内的超塑性变形行为。结果表明 ,工业态AZ31镁合金表现出良好的超塑性 ,其最高断裂延伸率达到 314%,应变速率敏感指数达 0 .4。显微组织观察和断口分析表明 ,工业态AZ31镁合金超塑变形主要由晶界滑动机制所控制 ,同时 ,动态再结晶也是合金超塑变形的一种协同机制。  相似文献   

11.
The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.  相似文献   

12.
Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.  相似文献   

13.
In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.  相似文献   

14.
After nearly two years' tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry (SRIF), located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.  相似文献   

15.
韩磊 《腐蚀与防护》2015,36(1):84-90,94
综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。  相似文献   

16.
The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.  相似文献   

17.
On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes' collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.  相似文献   

18.
Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.  相似文献   

19.
正Harbin General Hydraulic Machinery Works Co.,Ltd.of Yilin Hydraulic Group is the most professional production base of large-scale metallurgy oil cylinder and oil machinery cylinder in the Northeast of China.The main products include metallurgy cylinder,swell-shrink cylinder,rotating injection device,lifting cylinder,main lifting jack,front lifting jack,engineering oil cyl-  相似文献   

20.
<正>Copyright Information For Authors As soon as an article is accepted for publication,authors will be requested to assign copyright of the article(or to grant exclusive publication and dissemination rights)to the publisher(respective the owner if other than Springer).This will ensure the widest possible protection and dissemination of information under copyright laws.More information about copyright regulations for this journal is available at  相似文献   

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