摘要：主要研究了挤压前的时效处理工艺对AZ80镁合金显微组织和力学性能的影响,同时利用扫描电子显微镜对试样断口进行分析。结果表明:挤压前时效处理可以明显细化晶粒;时效过程中析出的Mg_(17)Al_(12)粒子弥散分布在晶界处,在动态再结晶过程中起到阻碍晶界移动、阻止晶粒长大、细化组织的作用;随着时效时间的延长或者时效温度的升高,晶粒细化效果减弱;对时效后合金进行挤压,试样的屈服强度、抗拉强度和延伸率均提高。通过对断口形貌的分析发现,早期裂纹产生于晶界处粗大的第二相周围,导致了拉伸过程中延伸率的下降。挤压前时效处理对AZ80的强化效果为高性能镁合金的设计和开发提供了一种全新的思路。

摘要：针对镁合金的棒材的工业化制备和加工,提出了一种新型的镁合金复合挤压方法,将正挤压(Extrusion)和剪切(Shear)结合(简称ES),建立了ES挤压的三维有限元热力耦合模型及条件,模拟了ES挤压的流动网格、累积应变演化,设计并制造了适合于卧式挤压机上的ES挤压模具,进行了ES工艺实验。数值模拟结果表明,ES挤压可以显著提高镁合金变形过程的累积应变;试验结果表明,ES挤压可以得到尺寸很小的动态再结晶晶粒,并改善了组织均匀性;理论分析表明,ES挤压过程镁合金具有多级动态再结晶的特性,可以逐步有效的细化微观组织。ES挤压在模具结构、工艺参数合理的条件下可以大大细化镁合金微观组织,并具有工业生产的实用性。

摘要：介绍了以UG/KF(Unigraphics/Knowledge Fusion)为开发平台的镁合金压铸模KBE系统,并以压铸模浇注系统设计为例对建立的系统知识库、功能模块及其程序实现流程进行了详细分析;充分利用UG软件现有的CAD/CAM/CAE功能,将KBE技术紧密结合压铸模设计理论与实践的经验,确定了系统的体系结构。

摘要：A new severe plastic deformation （SPD） method that is extrusion-shearing （ES）, which includes initial forward extrusion and shearing process subsequently, was developed to fabricate the fine grained AZ31 Mg alloys. The components of ES die were manufactured and installed to gleeble1500D thermo-mechanical simulator. Microstructure observations were carried out in different positions of ES formed rods. The results show that homogeneous microstructures with mean grain size of 2 μm are obtained at lower temperature as the accumulated true strain is 2.44. Occurring of continuous dynamic recrystallization （DRX） is the main reason for grain refinement during ES process. The experimental results show that the ES process effectively refines the grains of AZ31 magnesium. The production results of ES extrusion with industrial extruder under different extrusion conditions show that the ES extrusion can be applied in large-scale industry.

摘要：通过设计制作一套可获得不同凝固冷却速度的镁合金熔炼与浇注装置,采用多通道连续温度记录仪,获得了对应不同凝固冷却速度下的AZ91镁合金试样。用定量金相分析之截线法测定了各个试样的二次枝晶间距,并对不同凝固冷却速度下的组织特征做了简要分析。用数学回归的方法得到了AZ91镁合金的凝固冷却速度与二次枝晶间距的定量关系式。

摘要：本文分析了镁合金管材普通挤压成形应用发展的技术瓶颈和内在根源,总结了各种塑性变形工艺和稀土元素对镁合金管材组织性能的影响及基本原理、特点。分析了多道次等通道挤压、平行管道等通道挤压-反向挤压等多道次大塑性成形工艺及管材组织特征,发现多道次大塑性变形可改进组织,但成本高、工艺复杂;综述了单道次复合大塑性成形如管状等通道挤压、循环膨胀-挤压、旋转-反向挤压、挤压剪切塑性成形工艺等工艺原理及管材的组织特点,表明单道次复合大塑性成形工艺简单;通过在镁合金中添加微量稀土元素,能够弱化或随机化变形织构,强度和塑性都能得到较大提升。论文对镁合金管材塑性变形工艺的原理进行了分析及总结,指出了采用单道次新型复合大塑性成形工艺及低稀土镁合金作为管材材料,进行有效的晶界与织构设计是提高镁合金管材质量的有效途径,论文对相关研究进行了展望,总结了目前亟待解决的问题。

摘要：设计制作了一套可获得不同凝固冷却速率的镁合金熔炼与浇注装置,采用多通道连续温度记录仪,获得了对应不同凝固冷却速率下的AZ31镁合金试样。用定量金相截线法测定了试样的二次枝晶间距,并对不同凝固冷却速率下的组织特征做了简要分析,用数学回归的方法得到了AZ31镁合金的凝固冷却速率与二次枝晶间距的定量关系式。该关系式完全符合以金属凝固理论推导出的凝固速度与枝晶间距的经典关系式。

摘要：A new severe plastic deformation method for manufacturing tubes made of AZ31 magnesium alloy with a large diameter was developed,which is called the TCESE(tube continuous extrusion−shear−expanding)*** process combines direct extrusion with a two-step shear−expanding *** influences of expanding ratios,extrusion temperatures on the deformation of finite element meshes,strain evolution and flow velocity of tube blanks during the TCESE process were researched based on numerical simulations by using DEFORM-3D *** results show that the maximum expanding ratio is 3.0 in the TCESE *** deformation of finite element meshes of tube blanks is inhomogeneous in the shear−expanding zone,and the equivalent strains increase significantly during the TCESE process of the AZ31 magnesium alloy.A extrusion temperature of 380°C and expanding ratio of 2.0 were selected as the optimized process parameters from the numerical simulation *** average grain size of tubes fabricated by the TCESE process is approximately 10μ*** TCESE process can refine grains of magnesium alloy tubes with the occurrence of dynamic ***(0001)basal texture intensities of the magnesium alloy tube blanks decrease due to continuous plastic deformation during the TCESE *** average hardness of the extruded tubes is approximately HV 75,which is obviously improved.

摘要：根据实际生产工艺,借助***有限元分析软件,建立宽带钢多道次热连轧有限元模型,对宽带钢的轧制过程的温度场、轧制力特性等进行了仿真研究。仿真结果与实测值误差非常小,终轧温度与实测温度误差在±13°C以内,各道次轧制力与实测值误差在±10%以内。在此基础上,讨论不同工艺参数对带钢温度场,轧制力的影响,为优化轧制工艺提供理论依据。

摘要：介绍了常见Mg-Gd系合金的力学性能,以是否生成长周期堆垛有序相为划分标准,重点分析了关键强化相β′、长周期堆垛有序相及二者形成的复合强化模型的强韧化机理,探讨了目前研究的不足之处,最后,提供了设计高强Mg-Gd系合金的思路。