Microstructure Study on Semi-solid 60Si2Mn during Compressing

The microstructure behavior and deformation mechanism of semi-solid 60Si2Mn fabricated by electromagnetic stirring under different deformation conditions during thixoforming are studied by means of Gleeble-1500 thermal-strain-stress simulator. The micro- structure of deformed 60Si2Mn and that of the non-deformed are compared. The results show that the grain size within deformation zone decreases as the amount of deformation increases or deformation temperature decreases, but deformation fate has small effect on grain size when the rate is very low. Besides, there is a critical amount of deformation to reduce grain size. These results offer theoretical and experimental basis for further producing semi-solid material with high melting temperature and direct forming of semi-solid slurry.     

Semi-solid slurry preparation and rolling of 1Cr18Ni9Ti stainless steel

The preparation and rolling of the semi-solid slurry 1Cr18Ni9Ti stainless steel were researched. The experimental results show that when stirred for 2-3 min under the given test condition, the semi-solid slurry with about 50%-60% (volume fraction) solid and the spherical primary austenitic grains in the size of 100-200μm can be obtained, and it is easy to be discharged from the bottom little hole of the stirring chamber. The semi-solid slurry of 1Cr18Ni9Ti stainless steel can be rolled into the given plate successfully. However, the solid phase and liquid phase are easily separated in the rolling process, so that the solid primary austenitic grains are concentrated in the center and the liquid phase is near the edge of the rolled plate. The strengths of the plate rolled in the semi-solid state are higher than that of the traditionally repeated hot-rolled plate of 1Cr18Ni9Ti stainless steel.     

Microstructure evolution of Al-Si semi-solid slurry by gas bubble stirring method

A novel technique of introducing gas bubble stirring during solidification was studied to prepare Al-Si semi-solid slurry. The microstructure evolution of the slurry during slow cooling process after stirring was investigated. The effects of the solidification rate on the microstructure of the semi-solid slurry were investigated under three different solidification conditions. The results show that fine non-dendritic slurry can be obtained using the gas bubble stirring method. Ripening and coarsening of primary Al grains are observed during the slow cooling process, and at last coarsened eutectic Si appears. Primary Al grains with different sizes and eutectic Si are obtained, corresponding to three different solidification rates.     

3-D thermo-mechanical coupled FEM simulation of continuous hot rolling process of 60SiMnA spring steel bars and rods

The 3-D thermo-mechanical coupled elasto-plastic finite element method (FEM) was used for the simulation of the twopass continuous hot rolling process of 60SiMnA spring steel bars and rods using MARC/AutoForge3.1 software. The simulated resuits visualize the metal flow and the dynamic evolutions of the strain, stress and temperature during the continuous hot rolling, especially inside the work-piece. It is shown that the non-uniform distributions of the strain, stress and temperature on the longitudinal and transverse sections are a distinct characteristic of the continuous hot rolling, which can be used as basic data for improving the tool design, predicting and controlling the micro-structural evolution of a bar and rod.     

基于表观黏度模型的AZ31流变铸轧数值模拟

以AZ31半固态合金为研究对象,应用流体模拟软件Fluent对其铸轧过程进行研究。通过使用简单等温稳态黏度模型、Carreau黏度模型、简单连续冷却黏度模型、黏度不变模型,得到了相应的铸轧温度分布、流场分布以及黏度分布,并进行了比较和分析。结果表明：在特定工况下,为保证出口处的合金刚好凝固而不会造成铸轧不成形或铸轧中断的最佳浇铸温度为880 K,此时Carreau黏度模型最适合AZ31半固态合金的铸轧过程。     

空冷贝氏体钢在弹体上的应用浅探

研究了空冷贝氏体钢在榴弹弹体上的应用．结果表明：贝氏体钢作为榴弹弹体钢不仅可以简化热处理工艺,而且可获得高的破片率,与５８ＳｉＭｎ和６０Ｓｉ２Ｍｎ钢相比,其破片率有较大幅度的提高．     

Evolution of microstructures in Al-Mn-Mg alloys during homogenization

0　ＩＮＴＲＯＤＵＣＴＩＯＮＡｌ Ｍｎｓｅｒｉｅｓａｌｌｏｙｓａｓｃｏｍｍｅｒｃｉａｌｏｎｅｓｈａｖｅｌｏｎｇｈｉｓ ｔｏｒｙ .Ｔｈｅｆｉｒｓｔｃｏｍｍｅｒｃｉａｌ 3ＸＸＸａｌｌｏｙｗａｓｄｅｖｅｌｏｐｅｄｉｎ190 6ａｎｄｔｈｅｍａｉｎａｌｌｏｙｉｎｇｅｌｅｍｅｎｔｓｏｆｔｈｉｓａｌｌｏｙａｒｅ 1.2 5ｗ (Ｂ) %Ｍｎａｎｄ 0 .13ｗ (Ｂ) %Ｃｕ .Ｉｎ 192 9,30 0 4ａｌｌｏｙｗｉｔｈ 1ｗ (Ｂ) %Ｍｇｅｌｅｍｅｎｔｃａｍｅｉｎｔｏｉｎｄｕｓｔｒｉａｌｕｓｅ .Ｏｖｅｒｐａｓｔｔｗｅｎｔｙ ｙｅａｒｓ ,3ＸＸＸｓｅｒ…     

稀土磁致冷Gd5Ge2(Si2-xMnx)化合物的结构及微观机制

利用X射线衍射和扫描电镜对Gd5Ge2(Si2-xMnx)结构及表面形貌进行了研究.并利用差示量热法对Gd5Ge2(Si2-xMnx)的磁热性能进行了研究.x射线衍射(XRD)测量分析表明Mn的替代不会影响母体Gd5Si2Ge2的晶体结构,样品中的主相仍然具有单斜结构(P1121/a),其晶体对称性不会随Mn含量的增加而改变.随着Mn含量的增加,晶粒逐渐变大,晶常数增大,体积膨胀,同时Mn和杂质相的析出量也在增加.少量的Mn元素替代Si可以提高Gd5Si2Ge2化合物的居里温度.     

铝合金的半固态成形技术

金属材料的半固态成形是一种能够获得致密组织及高性能零部件的近净成形技术,被认为是一项绿色成形新技术。在简要介绍半固态成形技术研究现状的基础上,着重叙述了作者进行高能超声波制备铝合金半固态浆料、半固态浆料流变压铸成形的试验研究。研究表明,超声制浆及半固态压铸成形工艺适合于铝合金零件的成形制造。含20％Si 的高硅铝合金Al-20Si-2Cu-1Ni经过半固态压铸成形,T6热处理后抗拉强度可达到310MPa,比传统液态压铸提高34％。     

Numerical simulation of the preparation of semi-solid metal slurry with damper cooling tube method

In semi-solid forming process, preparing the slurry with rosette or globular microstructure is very important. A new ap- proach named the damper cooling tube method (DCT), to produce the semi-solid metal slurry, has been introduced. To optimize the technical parameters in designing the apparatus, the finite volume method was adopted to simulate the flow process. The temperature effects on the rheological properties of the slurries were also considered. The effects of the technical parameters on the slurry proper- ties were studied in detail.     

Forging process modeling of cone-shaped posts

Using the rigid visco-plastic Finite Element Method (FEM), the process of forging for long cone-shaped posts made of aluminum alloys was modeled and the corresponding distributions of the field variables were obtained based on considering aberrance of grids, dynamic boundary conditions, non-stable process, coupled thermo-mechanical behavior and other special problems. The difficulties in equipment selection and die analysis caused by the long cone shape of post, as well as by pressure calculation were solved.     

铝热连轧温度场模拟在Marc中的实现

通过Gleeble-1500热模拟机等温压缩试验研究了1235铝合金流变本构模型．在此基础上,建立铝板带热轧二维MSC．Marc有限元模型,对热连轧过程温度场进行了模拟仿真,并分析了热连轧过程中的温度场变化规律．     

ZK60镁合金棒材挤压过程有限元分析

采用刚粘塑性有限元理论,分别用2mm/s、3mm/s、4mm/s、5mm/s的挤压速度,对ZK60镁合金棒材的挤压过程进行了数值模拟,观察棒材挤压过程中金属流动情况,并分析了挤压变形时工件内部的温度变化情况,以及应力、应变分布规律.以模拟出的挤压件流出模孔时等效应力应变的分布规律,确定该棒材挤压的最佳工艺参数.     

合金元素对Fe-Mn合金层错几率和阻尼性能的影响

对Fe-19Mn、Fe-17Mn-2Cr和Fe-19Mn-1.5Si这3种合金的层错几率和阻尼性能进行研究。采用倒扭摆测试合金的阻尼性能,XRD测试合金的层错几率和ε马氏体体积分数。结果表明,3种合金的阻尼性能都随着应变振幅的增加呈现近似线形增加,这可以通过Shockley不全位错的脱钉运动来解释;Si元素增加了Fe-Mn合金的层错几率和Shockley不全位错数量,但是由于原子半径的差异,其引起的晶格畸变很大,产生的空位等缺陷钉扎了Shockley不全位错的运动,因此显著降低了Fe-Mn合金的阻尼性能;     

基于ANSYS的地铁弹条强度模拟分析

针对地铁弹条的实际工况,采用UG建模,利用ANSYS-10．0仿真手段,对实际工作载荷下弹条中的应力和应变情况进行了计算机模拟．模拟结果显示：在压紧位移值和扣压量分别一定的情况下,改变对应的扣压量和压紧位移等边界条件后获得了弹条内部模拟应力分布和模拟最大应力值,模拟显示最大应力位置出现在地铁弹条的跟端弯曲圆弧位置;在两个影响因素中,压紧位移对弹条中的应力分布和最大应力值的影响更为显著．     

皮尔格冷轧无缝钢管成形过程组织演变过程研究

皮尔格冷轧技术作为冷轧无缝金属管材最主要的技术手段,具有材料利用率高、截面累积变形量大及加工精度高等特点,以LG-60皮尔格冷轧管机轧制304不锈钢为研究对象建立数值仿真模型,分析不同轧制工艺参数对皮尔格冷轧成形的影响规律。结合轧制实验,截取管材不同的变形段利用金相显微镜、扫描电镜以及X射线衍射仪分析研究了皮尔格冷轧过程中钢管组织演变规律,结果表明：本文所使用工艺参数条件均可以满足管材的塑性变形要求,但在轧制过程中极有可能形成裂纹或其他缺陷。因此通过对皮尔格冷轧仿真过程中轧制力、管材等效应力、残余应力以及外径回弹量等关键参数分析,获得基于送进量、回转角和Q值最优工艺参数,同时,发现轧制过程中随着变形量的增大,试样内部产生了大量位错,晶粒发生了碎化,晶粒尺寸减小,轧制过程中有奥氏体γ相转变为α''-马氏体相。     

二氧化硫液相浸取低品位软锰矿的动力学

研究了液相中二氧化硫对低品位软锰矿的浸出行为。考察了液相搅拌转速、温度、二氧化硫浓度及pH对锰浸出率的影响,研究了软锰矿粒径及表面元素相对含量随锰浸出率的变化,并对其浸出的动力学模型进行了分析。实验结果表明,搅拌转速为400r/min时可消除外扩散对锰浸出率的影响。锰浸出率随温度、二氧化硫浓度的升高而增大,随pH的增大而减小。当锰浸出率为80%时,软锰矿粒径减小约20%,表面锰含量减小73%,硅元素含量增大18%。动力学研究结果表明,软锰矿的浸出过程为扩散-化学反应混合控制过程,反应的活化能为36.85KJ/mol,二氧化硫浓度、氢离子反应级数分别为1.5595和0.5884。     

锰含量对15MnV钢组织性能的影响

采用热膨胀试验、热模拟试险和热轧空冷试验,研究了不同含锰量对15MnV钢相变点、组织和性能的影响,测试了不同锰含量的临界点、等温转变开始时间,观察了显微组织,确定了化学成分与15MnV钢临界点的回归公式,找出了锰含量及控轧后的终冷温度与组织细化的关系,并在此基础上进行了控轧控冷试验。试验表明,通过合适的控轧控冷,降锰后的15MnV钢性能可达原15MnV钢的水平。     

Modeling and Optimizing of Deformed Steel Bars Hot Rolling

Deformedsteelbarsarewidelyusedinconstructionengineering.Thetensilestfengthisthemainparameterthatdetermineswhetherdeformedsteelbarsaregoodornot.Intheprocessofhotrolling,therearemanyfactorsinfluencingthetensilestrengthofdeformedsteelbars,suchasMnandStc...     

Microstructure Characteristics and Apparent Viscosity of Hypereutectic Al-24%Si Alloy Melt During Semi-solid State Stirring

The microstructural evolution and apparent viscosity of hypereutectic Al-24%Si alloy during semi-solid state shearing were studied with a Searte type viscometer. When the alloy melt was continuously stirred from 720℃ to eutectic temperature, the primary Si crystals were gradually changed from elongated platelets to near-spherical shapes. It was found that some nondendritic a-phase formed when the melt was stirred below 585℃. The experiment showed that the semi-solid stirring had strong effect on inhibiting the anisotropic growth of Si crystals during solidification. The apparent viscosity of the alloy melt increased slowly with the decreasing of temperature before the formation of nondendritic α-phase, which caused the dramatic increase of apparent viscosity.