AZ31镁合金管材挤压成形数值模拟研究

根据等温压缩实验所得AZ31镁合金应力一应变数据,拟合出材料温成形应力一应变曲线,应用有限元法模拟AZ31镁合金管材的挤压成形,着重探讨了AZ31镁合金挤压成形过程中,温度、速度、润滑等因素对金属流动的影响,为管类零件挤压成形工艺提供了科学依据。     

铝合金组织特性在挤压成形过程中的响应行为

以铝合金7A04为研究对象,采用638T卧式挤压机对其在不同挤压工艺下的成形性能进行研究,并对挤压后材料的显微组织及力学性能进行表征,探讨了铝合金组织特性在不同的挤压温度和不同挤压速度下成形过程的响应行为。研究发现,铝合金的组织特性对挤压速度响应比温度显著。     

58SiMn钢双杯形件等温挤压成形金属流动规律研究

根据等温压缩实验所得的58SiMn钢应力一应变数据,应用刚塑性有限元法模拟58SiMn钢双杯形件等温挤压成形.着重探讨58SiMn钢等温挤压成形过程中变形力及金属流动规律,从而为该类零件等温挤压成形工艺提供科学的依据.     

某铝合金圆锥形壳体的温挤压成型工艺

针对7A04铝合金圆锥形壳体零件的结构特点及材料特性,绘制该零件的挤压件毛坯图,确定该零件的加工方案,并对该壳体毛坯的温挤压成形工艺进行研究.结果表明:采用温挤压成形的该壳体工件满足使用要求,可为此类零件生产工艺的设计提供参考.     

循环扩挤平面变形对7A04铝合金组织与性能的影响

多次循环扩挤成形技术是一种新型的大塑性变形技术,是制备亚微米或纳米级块体材料的有效方法之一。通过7A04铝合金经过一次循环扩挤平面变形的有限元模拟分析和挤压成形实验,并借助于ZEISS Image Alm金相显微镜、ZMT5105电子万能拉伸材料试验机、维氏硬度测试计等仪器设备,研究了不同变形道次下的循环扩挤平面变形对7A04铝合金的力学性能与显微组织的影响。研究结果表明:二道次挤压后试样的抗拉强度、屈服强度、硬度与伸长率均比一道次的高,晶粒细化效果更明显。     

7A04超硬铝合金壳体的精密成形工艺研究

采用镦挤与等温挤压相结合的精密成形工艺对某武器装备上7A04超硬铝合金壳体进行加工。通过分析确定了最佳的工艺方案,设计了热镦挤模具和等温挤压模具。在生产中应用该工艺可提高产品生产效率和材料利用率。     

7A04铝合金车轮半成品热变形行为研究

采用GLEEBLE-1500热模拟试验机研究了7A04铝合金车轮半成品的热变形及最佳热成形参数,使用金相显微镜分析微观组织。结果表明,在变形温度一定时,该铝合金的流变应力随应变速率的增加而逐渐增大;在应变速率一定时,其流变应力随变形温度的升高而降低。当变形温度为320℃时,晶粒仅发生形状的变化,其变形机制以动态回复为主;当变形温度为480℃时,出现了动态再结晶现象,从而使晶粒细化。铝合金车轮半成品热加工图中仅有一个功率耗散较大的区域(370℃~480℃,0.1 s~(-1)~0.003 s~(-1)),且其峰值功率耗散可达37%,失稳区的范围是:380℃~420℃,0.1 s~(-1)~1 s~(-1)。其优化的热加工参数与挤压态棒材及铸态7A04铝合金的优化热加工参数不同,表明多道次变形时,7A04铝合金热加工不宜选择单一的热变形参数。     

超高强铝合金7A04高温流变行为的研究

通过在Gleeble-1500热模拟实验机上对7A04铝合金进行高温压缩实验,研究了该合金变形温度在300～450℃,应变速率在0.01～10 s-1范围内的高温流变变形行为。结果表明:流变应力随变形温度的升高而降低,随着应变速率的增加而升高。建立了一个综合考虑应变、温度、应变速率三者影响的流变应力方程,预测值与拟合实验值非常接近,结果表明:该流变应力方程用来预测7A04铝合金材料一般加载情况下的热成形过程是比较可靠的。     

7A04铝合金热顶铸造圆锭裂纹问题的探讨

裂纹是铝合金铸锭或加工制品成为废品的重要原因之一,铸造时形成的微裂纹会导致挤压制品失效。7A04铝合金的有效结晶范围宽,线收缩率大,因此热顶铸造时易产生热裂纹,而且,随着铸锭直径的增大,裂纹的倾向性更高。以热应力理论为基础,分析了影响7A04铝合金热顶铸造圆锭裂纹的因素,结合生产实际进行探索,掌握了7A04铝合金产生裂纹的一般规律,通过控制化学成分、设计结构合理的结晶器等措施,减少了7A04铝合金热顶铸造圆锭裂纹废品。     

高强超高精度7A04超硬铝合金导轨型材的研制

概述了高档电子机柜用超高精度高强7A04超硬铝合金导轨型材的研制过程，并对导轨的材质、结构、成形方案、挤压模具以及挤压、拉矫工艺的选择进行了深入探讨。结果表明，与机加不锈钢导轨相比，此新轨重量轻、加工成本低、装配性能优良、载荷能力也毫不逊色，完全可取代机加不锈钢导舅，实现以铝代钢、以压加取代机加不锈钢导轨的预定目标。     

Effects of Multiple Plastic Deformations on Microstruc-ture and Mechanical Properties of 7A04-T6

The influences of multiple plastic deformations on microstructure and mechanical properties of 7A04-T6 alloy by isothermal compression experiments in different passes deformation on the 6300 kN extrusion press. The experimental results showed that the strength and elongation of 7A04-T6 alloy were increased firstly and then decreased as the deformation pass increases at above 400 ℃. The grains of 7A04-T6 alloy was refined firstly and then grow, the grain was become refinement after four deformations under this experimental conditions. The second phase η (MgZn2) in the matrix would precipitate after solution, precipitation strengthening taking place. It is obvious that the number of second phase which dissolve into the matrix will increase as the deformation pass increasing. So the tensile strength reached the highest after four deformations, is 590.9 MPa, yield strength is 532.5 MPa, and elongation is 12.4%. After four deformations of 7A04-T6 alloy, tensile fracture surface of samples was composed of the deep and uniform dimples, belonging to ductile fracture. Therefore, 7A04-T6 alloy has better comprehensive mechanical properties after four deformations.     

玄武岩颗粒增强7A04铝基复合材料的界面结构及力学行为

采用喷射成形技术制备7A04铝合金及玄武岩颗粒增强7A04铝合金复合材料,利用金相显微镜(OM)、透射电镜(TEM)、扫描电镜(SEM)和能谱(EDS)分析复合材料微观组织和界面结构,对比研究复合材料的力学性能。结果表明:玄武岩颗粒在铝基体中弥散分布,并与铝基体形成强力结合界面,玄武岩颗粒边缘的SiO2不断被反应生成的Al2O3取代,形成一层几十纳米厚度的高温反应层,反应生成的Al2O3强化玄武岩颗粒与铝基体的结合界面;弥散分布的玄武岩颗粒促进基体中位错增殖、空位形成和析出相的析出,析出相主要以板状的η(MgZn2)相和亮白色条状或椭球状的T(Al2Mg3Zn3)相为主,结合界面、高位错密度及弥散分布的第二相显著提高复合材料的力学性能,添加玄武岩颗粒的7A04铝合金复合材料的屈服强度和极限拉伸强度分别达667 MPa和696 MPa,与未添加玄武岩颗粒的7A04铝合金相比分别提高10.4%和10.1%。     

7A04铝合金热变形过程微观组织演变

以热模拟压缩实验和金相实验为基础,探讨7A04铝合金热压缩变形过程中应变速率和变形温度对流变应力和微观组织的影响规律。通过对实验数据进行回归分析,构建了该合金热压缩变形过程的微观组织演化模型。将建立的材料模型导入有限元软件DEFORM-3D中,对热压缩过程进行数值模拟。结果表明,所建立的微观组织演化模型可以很好的预测7A04合金在热变形过程中晶粒尺寸的演化规律。     

Microstructures and mechanical properties of BP/7A04 Al matrix composites

The microstructures and interface structures of basalt particle reinforced 7A04 Al matrix composites (BP/7A04 Al) were analyzed by using OM, TEM, SEM and EDS, and the mechanical properties of 7A04 Al alloy were compared with those of BP/7A04 Al matrix composites. The results show that the basalt particles are dispersed in the Al matrix and form a strong bonding interface with the Al matrix. SiO₂ at the edge of the basalt particles is continuously replaced by Al₂O₃ formed in the reaction, forming a high-temperature reaction layer with a thickness of several tens of nanometers, and Al₂O₃ strengthens the bonding interface between basalt particles and Al matrix. The dispersed basalt particles promote the dislocation multiplication, vacancy formation and precipitation of the matrix, and the precipitated phases mainly consist of plate-like η (MgZn₂) phase and bright white band-shaped or ellipsoidal T (Al₂Mg₃Zn₃) phase. The bonding interface, high dislocation density and dispersion strengthening phase significantly improve the mechanical properties of the composites. The yield strength and ultimate tensile strength of BP/7A04 Al matrix composites are up to 665 and 699 MPa, which increase by 11.4% and 10.9% respectively compared with 7A04 Al alloy without basalt particles.     

7A04-T6铝合金棒材生产工艺研究

通过优化7A04铝合金成分配比与均匀化处理工艺,采取双孔模具挤压、高温固溶处理与二段分级时效等方法,满足了用户对产品性能的要求,提高了生产效率,实现了批量化生产超高强铝合金挤压棒材的目标。     

Overheating temperature of 7B04 high strength aluminum alloy

The microstructure and overheating characteristics of the direct chill semicontinuous casting ingot of 7B04 high strength aluminum alloy, and those after industrial homogenization treatment and multi-stage homogenization treatments, were studied by differential scanning calorimetry(DSC), optical microscopy(OM) and scanning electron microscopy with energy dispersive X-ray spectroscopy(SEM-EDX). The results show that the microstructure of direct chill semicontinuous casting ingot of the 7B04 alloy contains a large number of constituents in the form of dendritic networks that consist of nonequilibrium eutectic and Fe-containing phases. The nonequilibrium eutectic contains Al, Zn, Mg and Cu, and the Fe-containing phases include two kinds of phases, one containing Al, Fe, Mn and Cu, and the other having Al, Fe, Mn, Cr, Si and Cu. The melting point of the nonequilibrium eutectic is 478 ℃ for the casting ingot of the 7B04 alloy which is usually considered as its overheating temperature. During industrial homogenization treatment processing at 470 ℃, the nonequilibrium eutectic dissolves into the matrix of this alloy partly, and the remainder transforms into Al2CuMg phase that cannot be dissolved into the matrix at that temperature completely. The melting point of the Al2CuMg phase which can dissolve into the matrix completely by slow heating is about 490 ℃. The overheating temperature of this high strength aluminum alloy can rise to 500-520 ℃. By means of special multi-stage homogenization, the temperature of the homogenization treatment of the ingot of the 7B04 high strength aluminum alloy can reach 500 ℃ without overheating.     

Effect of large cold deformation after solution treatment on precipitation characteristic and deformation strengthening of 2024 and 7A04 aluminum alloys

1Introduction Studies on thermomechanical treatment of aluminum alloy can date from the1960s[1,2].A great deal of achievements concerning this study has been obtained after near40years of development[3?7].Among them,the achievement of intermediate thermom…     

原位TiC颗粒对喷射沉积7093铝合金微观组织的影响

采用喷射沉积及原位反应喷射沉积方法制备7093铝合金及7093+TiC铝合金,研究试验合金420℃热挤压及不同固溶处理后的微观组织和力学性能。探索原位TiC颗粒对喷射沉积7093铝合金组织的影响。结果表明,原位TiC颗粒能够提高喷射沉积7093铝合金的再结晶温度10℃,当固溶温度达到490℃时,7093+TiC铝合金中的富Cu颗粒基本溶解,但并未出现过烧现象。采用450℃×3h+480℃×3h+120℃×24h的制度处理后,7093+TiC铝合金的抗拉强度达754 MPa,伸长率达7.1%。     

Microstructural evolution of high strength 7B04 ingot during homogenization treatment

The evolution of the microstructure and phases of the direct chill semicontinuous casting ingot of 7B04 super-high strength aluminum alloy during homogenization treatment was studied with metallographic analysis, scanning electron microscopy（SEM）, energy spectroscopy and differential scanning calorimetry（DSC）. The results show that a considerable amount of non-equilibrium eutectics containing AI, Zn, Cu and Mg exist in the direct chill semicontinuous casting ingot of 7B04 super-high strength aluminum alloy, and their melting point is 478℃. During homogenization treatment at 470℃, these eutectics dissolve into the matrix partly, coarsen and also transform into Al2CuMg phase whose equilibrium melting point is 490℃ in the alloy. Moreover, the homogenization treatment at 470℃ for 72 h results in the disappearance of the non-equilibrium eutectics though Al2CuMg phase can not dissolve completely.     

高温自蔓延过程中的挤压工艺对合成Ni_3Al-B-Cr合金的组织及力学性能的影响(英文)

采用高温自蔓延及挤压工艺制备Ni3Al-0.5B-5Cr合金,研究挤压工艺对合成合金的微观组织及力学性能的影响。结果表明:合成后的挤压工艺可使合成合金进一步致密并能有效地细化其组织。X射线衍射及透射电镜观察发现除了Ni3Al基体外,合金中还含有Al2O3、Ni3B及Cr3Ni2析出相。与无挤压合成的合金有所不同,合金在高温自蔓延合成及挤压过程中经历了大变形和再结晶过程,其促进了组织的细化并降低了晶粒的取向差。此外,合成后的挤压工艺促使Al2O3颗粒重新分布且减少了γ-Ni相。与无挤压合成的合金相比,高温自蔓延合成及挤压工艺制备的合金具有更好的室温力学性能。