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1.
含两种尺度微裂纹的高强铝合金的断裂韧性模型   总被引:1,自引:1,他引:0  
基于高强铝合金在断裂过程中萌生不同尺度微裂纹的机制,用断裂力学建立两种尺度微裂纹影响应力应变场的规律,导出高强铝合金拉伸延性与两种尺度微裂纹的关系,由断裂韧性与拉伸延性的关系建立了高强铝合金断裂韧性与双级微裂纹的非线性关系模型。通过模型解析,分析两种尺度微裂纹体积分数对高强铝合金断裂韧性的影响规律。结果表明:随着一级微裂纹体积分数的增加,材料的断裂韧性开始迅速下降,然后缓慢降低;在较大尺度微裂纹之间萌生小尺度微裂纹,将显著降低合金的断裂韧性。将高强铝合金的结晶相作为一级微裂纹,将弥散相和粗大析出相作为二级微裂纹,预测高强铝合金断裂韧性随两种尺度相(微裂纹)的变化,其规律与实验结果较为吻合。利用模型解析与实验验证结果,提出了改善高强铝合金断裂韧性的组织控制方向。  相似文献   

2.
含有第二相的高强铝合金疲劳模型   总被引:3,自引:0,他引:3  
基于疲劳裂纹尖端的应力和应变以及高强铝合金中不同尺度第二相性态对其延性的影响,建立了高强铝合金中粗大第二相、中间尺度第二相以及细小时效强化相性态与其疲劳裂纹扩展速率之间的多元非线性关系模型。结果表明:对于2024铝合金的疲劳扩展速率,该模型的预测趋势与他人的实验研究结果吻合良好。同时借助于对该模型的理论分析,提出了在确保高强铝合金强度不降低的前提下降低其疲劳裂纹扩展速率的优化方案。  相似文献   

3.
Al-Cu-Mg合金的断裂韧性与拉伸延性模拟   总被引:2,自引:2,他引:0  
基于铝合金中的脆性结晶相在外力作用下发生断裂而形成微裂纹的过程服从Weibun分布,建立了Al-Cu-Mg合金断裂韧性与拉伸延性的细观力学模型。模型的解析表明,在外力作用下由结晶相断裂而形成的微裂纹的体积分数随着外加应力的增加而增加:在相同的外加应力作用下,结晶相含量较高时微裂纹的体积分数也较高。同时模型的计算表明,Al-Cu-Mg合金的拉伸延性及断裂韧性与结晶相的含量及尺寸有很大关系;拉伸延性与断裂韧性随着结晶相体积分数与尺寸的增加而减小;因此通过对铝基体的纯化,减少Fe与Si元素的含量或者通过强化固溶处理可以降低结晶相的体积分数与尺寸,从而提高Al-Cu-Mg合金的拉伸延性与断裂韧性。  相似文献   

4.
含有不同尺度量级第二相的高强铝合金断裂韧性模型   总被引:10,自引:3,他引:7  
基于合金中不同尺度第二相对其塑性的影响以及塑性与韧性指标之间的人在联系,建立了高强铝合金中粗大第二相颗粒,中间尺寸第二相颗粒以及时效强化第二相颗粒形态与其断裂韧性间的多元非线性关系解析模型。借助于该模型的理论分析,可以得出不同尺度第二相颗粒尺寸,体积分数改变对高强铝合金断裂韧性的定量影响,并且可以解释铝合金板材断裂韧性的取向效应以及加工变形对断裂韧性的弱化作用,更进一步地能够给出在确保铝合金高强度的前提下改善其断裂韧性的优化方案。  相似文献   

5.
雾化沉积高强铝合金材料的组织与性能   总被引:2,自引:0,他引:2  
研究了雾化沉积快速凝固高强铝合金材料的显微组织与拉伸性能。结果表明:采用雾化沉积技术可显著提高高强铝合金的强度指标,同时拉伸塑性保持与铸锭冶金材料相当的水平。过饱和固溶体、时效析出相以及变形和热处理过程形成的弥散相构成材料的主要强化相。  相似文献   

6.
通过实验和理论计算研究Al-Cu-Mg-(Ag)合金的拉伸延性.研究表明:Al-Cu-Mg-(Ag)合金的拉伸延性与析出相的体积分数和尺寸有重要关系:析出相体积分数的增加将减小位错的有效滑移距离,从而降低合金的拉伸延性;在时效过程中,合金的拉伸延性首先随着时效时间的延长而降低,达到时效峰值后,拉伸延性随着时效时间的进一步延长而增大;Ag的加入可以提高Al-Cu-Mg合金中析出相的体积分数和强度,但降低合金的拉伸延性:通过控制时效时间虽然可以提高合金的拉伸延性,但同时将降低合金的屈服强度.  相似文献   

7.
通过将改进的X-W延性金属断裂模型结合修正的Von-Mises准则嵌入ABAQUS/explicit用户材料子程序VUMAT的方式,对一系列铝合金2A12-T4试件的渐进断裂过程进行数值模拟,该模型以连续损伤力学为基础,并考虑静水压力和Lode角对损伤变量的作用。为了预测该模型的有效性并预测金属的延性断裂,对铝合金2A12-T4光滑圆棒、带缺口的棒材和紧凑拉伸试件(CT试件)进行单向拉伸试验及数值模拟。同时对比分析几何非线性和屈服准则的影响在数值仿真计算中的差异。结果表明,该断裂模型结合修正的von-Mises屈服准则可很好地预测2A12-T4试件渐进破坏试验的载荷-位移曲线及各试件的宏观断裂形貌。其中,"隧道"效应能够很好地解释CT试件处于平面应变状态的中心层和平面应力状态的表面层的抗断裂能力的差异。  相似文献   

8.
李姚君  韩振  兰箭 《金属热处理》2021,46(3):109-112
利用X射线衍射仪和DSC差热扫描量热仪进行测试,结合铝合金的析出相强化和位错强化理论模型,研究了在固溶-拉/压冷变形-时效过程中2A14铝合金强度的变化规律。结果表明:相比于压缩冷变形,拉伸冷变形引入的位错密度较大,因而位错强化作用更强;拉伸冷变形欠时效阶段(θ相析出之前)促进合金中强化相θ′相的析出,过时效阶段(θ相析出之后)抑制θ相的析出,拉伸冷变形的析出强化效果更好。经过拉伸冷变形的2A14铝合金时效强化效果更加显著。  相似文献   

9.
通过对YL112压铸铝合金成分微调,以改变微观组织及提高YL112铝合金的力学性能。基于合金设计原理来改善YL112铝合金的强度及延展性,通过添加微量Sr与Mn来改善脆性共晶硅及富铁相的形态,并降低合金的Cu与Fe含量来减少铸件内脆性Al2Cu(Mg)及富铁相,来改善脆性;通过扫描电子显微镜观察微观结构、拉伸性能分析来分析试验效果。试验结果表明:通过七组试验的对比分析,经复合成分微调的YL112Des铝合金能有效改善YL112铝合金的延性;经过合金成分微调的YL112Des铝合金具有较高的抗拉强度及伸长率,抗拉强度和伸长率分别增加至182 N/mm~2和5. 9%。  相似文献   

10.
对6014铝合金进行了常温拉深试验,采用不同的拉深凸模速度,研究了该铝合金变形中的组织力学行为;对6016铝合金进行热拉伸试验,相同应变速率下采用不同的拉伸温度,研究了该铝合金在热拉伸过程中的组织力学行为。实验表明:随着凸模速度(10~30 mm·min~(-1))增加,6014铝合金的常温拉深深度增大;随着拉伸温度(400~550℃)升高,6016铝合金的硬度增大,且沿拉伸轴向硬度值波动越大;在应变速率为1 s~(-1)、温度为500℃下热拉伸,变形区有明显的动态再结晶过程,进一步升高温度会造成再结晶组织的晶粒粗化;6014和6016铝合金中均存在大量的Al、Fe、Si结晶相,但原始组织中6016的析出相更弥散,尺寸大小更均匀,更集中分布于晶界附近;比较6014铝合金常温拉深组织和6016铝合金热拉伸组织,冷变形后的晶粒组织更均匀,热拉伸后的晶粒尺寸差异很大,会降低材料变形后的力学性能。  相似文献   

11.
1. Introduction Titanium is one of the most effective grain refinement elements of aluminum alloys. The grain of aluminum alloys can be effectively refined if containing up to 0.2% titanium, which results in improvement of mechanical properties and performance [1-8]. Titanium is usually added into aluminum melt by melting Al-Ti or Al-Ti-B (Ti/B= 5:1) master alloy. This requires strict control in melting temperature and holding time, resulting in the complicacy to control the quality of allo…  相似文献   

12.
It is usual to observe that multi-scale structures can lead to combined strength and ductility both in aluminum alloys and steels, but related research has been seldom reported yet in magnesium alloys. In this study, applying traditional one step extrusion, we have successfully obtained a bimodal (Mg-9Gd-4Y-0.5Zr) alloy capable of ultra-high strength. The characterized sample reveal a bi-modal microstructure with two constitutions, i.e. stretched coarse-grain region with strong basal fiber texture and recrystallization fine-grain region. The bi-modal structured sample exhibit excellent mechanical properties with an ultimate strength 508 MPa and elongation 8% via 400 °C extrusion and subsequently 200 °C-60 h peak aging process. Ultra-high strength can be attributed to its strong extrusion texture in stretched coarse grains and dispersed nano-scale precipitates. This unique bimodal structure could be produced easily by one step extrusion, which is quite reliable and low costs in industrial applications of magnesium alloys with ultra-high strength as well as ideal ductility.  相似文献   

13.
Novel alloys with high aluminum addition, so-called δ-transformation-induced plasticity (TRIP), have been developed recently for the third generation of advanced high strength steels for automotive applications, which are promising owing to the potential weldability as well as the combination of strength and ductility. In addition, the high aluminum addition results in a density reduction of approximately 5% in these δ-TRIP alloys without sacrificing the Young’s modulus in uniaxial tensile tests. The origin of δ-TRIP concept is introduced first with a review of the published work on δ-TRIP alloys. This review will include methodology for retention of δ-ferrite in casting, rolling and welding conditions, microstructure evolution by austempering, as well as microstructures–properties relationship involving the roles of blocky and lath retained austenite. In addition, currently unresolved problems will be discussed regarding the fundamentals of materials design, automotive application, and industrial manufacturing.  相似文献   

14.
The weldability of aluminum bronze alloys lends it to fabrication of items such as pipes and pressure vessels. Thus, obtaining high strength along with good ductility is necessary. Gas tungsten arc welding of Cu–7Al–3Fe aluminum bronze alloy was performed by variation of some parameters such as shielding gas flow rate, preheat and post weld heat treatment. Optical and scanning electron microscopy along with EDX analysis was applied for different samples. Microhardness measurements and tensile tests were performed to see the effect of these parameters on ultimate tensile strength and ductility of samples.  相似文献   

15.
Development on research of advanced rare-earth aluminum alloy   总被引:9,自引:0,他引:9  
1 INTRODUCTIONTheeffectofrareearthandtransitionelementsonthealuminumalloyisevidentfortheirspecialelec tronicstructures ,andthishasattractedattentionsofmanyscientists .Inthepast ,theresearchontherareearthaluminumalloyswascarriedoutmainlyonthebasisofassignmentofthespecifictypeandstrategy ,especiallyinChina ,andexplorationsoftheapplica tionoftherareearths (richresourceinChina)inalu minumalloysweremostlyconcentratedontheeffectofmischmetalonsomecommercialaluminumalloys ,whichwasthecertainoffs…  相似文献   

16.
A comparative study of the mechanical properties of 20 experimental alloys has been carried out. The effect of different contents of Si, Cu, Mg, Fe and Mn, as well as solidification rate, has been assessed using a strength-ductility chart and a quality index-strength chart developed for the alloys.

The charts show that the strength generally increases and the ductility decreases with an increasing content of Cu and Mg. Increased Fe (at Fe/Mn ratio 0.5) dramatically lowers the ductility and strength of low Si alloys. Increased Si content generally increases the strength and the ductility. The increase in ductility with increased Si is particularly significant when the Fe content is high. The charts are used to show that the cracking of second phase particles imposes a limit to the maximum achievable strength by limiting the ductility of strong alloys. The (Cu + Mg) content (at.%), which determines the precipitation strengthening and the volume fraction of Cu-rich and Mg-rich intermetallics, can be used to select the alloys for given strength and ductility, provided the Fe content stays below the Si-dependent critical level for the formation of pre-eutectic α-phase particles or β-phase plates.  相似文献   

17.
汽车轻量化先进铸造技术   总被引:1,自引:0,他引:1  
全面评述了用于汽车轻量化的铸造铝和镁合金及铸造工艺的发展.已开发的汽车用新型合金有耐磨铝合金、抗蠕变镁合金及高强度/韧性镁合金.在工艺前沿方面,开发了真空辅助压铸和高真空压铸技术,用于生产高整体性的车体和底盘零件.用低压金属型铸造工艺生产结构用薄壁空心铸件.包覆铸造技术不断得到发展,使用混合材料设计汽车的子系统,例如发动机支架、仪表板梁成为可能.开发的模拟工具用来预测,不同组分之间的界面相互反应和包覆铸造系统的结构完整性,并且已被铸造实验证实.  相似文献   

18.
SiC particulate or whisker-reinforced aluminum alloys are very attractive for applications requiring high stiffness coupled with a comparatively light weight. The dispersion strengthened Al alloys produced through the rapid solidification processing/powder metallurgy route demonstrate superior elevated temperature strength and microstructural stability, extending the useful service temperature of Al alloys to 350°C. However, low ductility and poor fracture toughness levels dictate that stringent controls regarding reinforcement quality and the purity of the matrix alloy, powders and processing are implemented to maximize the alloys’ increased stiffness and strength. This paper compares mechanical behavior through structure-property relationships currently being established for many new aluminum alloys.  相似文献   

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