等径角挤压Al-4%Mg-0.3%Ce合金的拉伸及断裂行为

对Al-4％Mg-0．3％Ce合金进行了不同道次和路径的等径角挤压（ECAP）加工,对其所加工样品在室温下进行了10^-4～10^-1s^-1不同应变速率的拉伸试验及其断口观察,探讨了ECAP合金的室温拉伸及断裂行为,并与常规热挤压进行了对比分析。结果表明,ECAP合金表现出更高的室温屈服强度,经过不同道次和路径ECAP的合金的拉伸断裂方式为切断型,而常规热挤压合金的拉伸断裂方式则为正断型。     

制样方法对铝挤压管材整管拉伸试验的影响

通过对铝合金挤压管材拉伸试验中采用圆塞头加塞拉伸试样、扁塞头加塞拉伸试样、全压扁无塞头拉伸试样测试结果对比分析，结果表明，3种制样方法对拉抗强度影响不大，但对伸长率有较大的影响，采用圆塞头试样、扁塞头试样，试验所得性能能够准确地反映铝合金挤压管材的实际力学性能。     

深孔壁锥形件冷加工工艺研究

通过对锥形件产品的研制，论证了采用复合挤压、变薄拉伸和扩锥挤压相结合的工艺方法是加工深孔薄壁锥形件的可靠工艺方法，得出了变薄拉伸加工中加工率不应处于临界加工率状态的结论。     

7050高强铝合金孔板的挤压强化与拉伸试验研究

针对航空用7050高强铝合金的孔板件拉伸性能进行试验研究与模拟分析,并对不同过盈量 (0%～11.11%) 的孔挤压强化效果进行了对比分析。研究表明:孔板的表观强度、延伸率和弹性模量均降低,但塑性失稳点应变却有很大程度的提高;孔挤压强化提高了孔壁处材料的屈服强度,改善了孔表面的受力状态,使得应力峰值得到钝化,并扩大了孔壁沿厚度方向的平面应变范围,因此拉伸断口随孔挤压量的变化呈规律性的变化;孔挤压强化后残余拉、压应力峰值随挤压量的增加而增加,且其峰值出现的部位随挤压量的增加而向远离于孔壁的深处转移。     

Pd／Ag纤维复合材料的制备工艺

用包套拉伸法和挤压法制备Ｐｄ／Ａｇ纤维复合材料，并通过金相和电子显微镜分别观察其微镜分别观察其微观结构，测试其性能，如电阻率，硬度，强度及接触电阻等。通过对比其工艺性及所得材料的微观结构和性能，认为挤压法优于包套拉伸法。此种Ｐｄ／Ａｇ纤维复合材料适合Ｐｄ／Ａｇ型复合铆钉和生产复铜铆钉。     

钛-铜复合棒的主要生产方法及其基本特点

重点介绍了拉伸法、挤压或挤压 拉伸法、爆炸或爆炸 轧制法等钛铜复合棒材的生产方法及其基本特点。并分析了生产方法对产品质量的影响。     

阶梯件拉伸挤压复合模设计

通过分析零件的工艺特点,设计了拉伸挤压复合模,不仅可提高零件质量,而且可提高生产效率。     

Dependence of Microstructure, Texture and Tensile Properties on Working Conditions in Indirect-Extruded Mg-6Sn Alloys

通过光学显微镜（OM）、扫描电子显微镜（SEM）、X射线衍射仪（XRD）和电子材料试验机研究了反向挤压Mg-6Sn合金的组织、织构和拉伸性能与挤压条件（挤压速度和初始坯料温度）间的依赖关系。研究结果表明：反向挤压 Mg-6Sn 合金的晶粒尺寸、再结晶体积分数和动态析出第二相体积分数在很大程度上取决于反向挤压参数,随着挤压速度和初始坯料温度的升高,合金的织构强度减弱。通过控制挤压速度和初始坯料温度,经高温挤压后的合金表现出最高的抗拉强度。对于商业 AZ31 镁合金而言,合金的强度随着挤压温度的升高而降低。本研究的 Mg-6Sn 合金经高温挤压后的抗拉强度和经低温挤压后的 AZ31 合金相当。上述研究结果表明 Mg-6Sn 合金是一种适合于高速度挤压的新型合金系。     

自动变速箱飞轮成形工艺研究

根据零件结构、尺寸特点,对反挤压工艺和拉伸工艺进行了比较,制定了拉伸和镦粗成形复合工艺,并在同一副模具内分不同阶段实现复合成形。并用塑性成形模拟软件Deform_3D对拉伸成形和镦粗成形进行了数值模拟,证明了该工艺的可行性。该成形工艺可极大地降低能耗,提高生产效益。     

铝合金外壳反挤压工艺及模具设计

叙述了用反挤压工艺代替多道变薄拉伸工艺生产铝合金外壳的优点。对铝合金外壳进行了工艺分析、制订了挤压件图、计算了毛坯尺寸及反挤压力。介绍了毛坯制备处理、反挤压模具结构设计及主要零件的加工技术要求。     

矩形管挤压拉伸工艺及模具设计

针对我厂矩形管（90mm×60mm×2.0mm）生产中存在的尺寸精度及表面质量低的问题,从理论分析其产生原因,并对原生产工艺及模具设计进行改进,提出了合理的改进方案,经生产后产品各项技术指标均满足用户的使用要求。     

Formulas of Tension of Continuous Rolling Process

The development of computer controlled continuous rolling process calls for a mathematical expression that can express the inequality condition of "constant flow". Tension is the link of the continuous rolling process. From the condition of dynamic equilibrium, a differential equation of tension is given out. On the basis of the physical rules established from the industrial practice and experimental studies, the law of volume constancy, the linear relation of forward slip and tension, the state equation of continuous rolling, the formula of dynamic tension, and the formula of static tension have been obtained. These formulae reflect the functional relations between tensions, thickness, roll velocity, and time in the continuous rolling process. It is implied that the continuous rolling process is a gradually steady, controllable, and measurable dynamic system. An assumption of predicting the thickness of a steel plate using these tension formulae is also put forward.     

桥壳钢边部裂纹缺陷原因分析

桥壳钢边部出现线状裂纹缺陷,钢板开裂发生在距离边部 20mm范围之内。通过金相显微检验对裂纹产生的原因进行分析,检验结果表明：钢板传动侧与操作侧边部表层均观察到厚度约 150μm的贝氏体组织,钢板板宽方向的其他部位表层组织与试样正常组织相同,均为铁素体＋珠光体。由此可知,钢板边部冷速过快导致贝氏体组织出现,贝氏体塑性较铁素体＋珠光体差,在钢板卷取过程中导致开裂的发生。     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

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.     

Coupled Influence of Temperature and Strain Rate on Tensile Deformation Characteristics of Hot-Extruded AZ31 Magnesium Alloy

To explore the coupled effect of temperature T and strain rate_e on the deformation features of AZ31 Mg alloy,mechanical behaviors and microstructural evolutions as well as surface deformation and damage features were systematically examined under uniaxial tension at T spanning from 298 to 523 K and_e from 10-4to 10-2s-1. The increase in T or the decrease in_e leads to the marked decrease in flow stress, the appearance of a stress quasi-plateau after an initially rapid strain hardening, and even to the occurrence of successive strain softening. Correspondingly, the plastic deformation modes of AZ31 Mg alloy transform from the predominant twinning and a limited amount of dislocation slip into the enhanced non-basal slip and the dynamic recrystallization(DRX) together with the weakened twinning. Meanwhile, the cracking modes also change from along grain boundaries(GBs) and at twin boundaries(TBs) or the end of twins into nearby GBs where the DRX has occurred. The appearance of a stress quasi-plateau, the formation of large-sized cracks nearby GBs, and the occurrence of continuous strain softening, are intimately related to the enhancement of the non-basal slip and the DRX.     

Stress Analysis of the Aperture in Compound Pipeline by FEM

There is a cyclical aperture at a certain part of the fiberglass reinforced plastic compound pipeline with a stainless steel pipe as a liner, which becomes the weakness of the conduit. The field of stress and strain of the aperture was investigated using the nonliner finite element code Marc. The results of the finite element analysis showed that there were concentrations of stress and strain in the layer of stainless steel at the part of the pipeline where the aperture existed. The method to solve these problems was also discussed.     

在线液体颗粒计数器的校准对滤纸多次通过试验结果的影响

分析了颗粒计数器校准前、后5种尺寸的颗粒数变化情况,并用实验验证了颗粒计数器的校准对滤纸多通试验结果的影响,校准前平均过滤比值均低于校准后的值。此外,分析说明了用颗粒数补偿法来替代颗粒计数器校准会降低试验结果的准确性,明确了定期对颗粒计数器进行校准的重要性。     

The influence of the microstructure of three Al–Si alloys on the cutting-force amplitude during fine turning

When cutting metallic materials, the magnitude and the variation of the amplitude of the cutting force and the quality of the treated surface are of major importance. During the fine turning of alloys that have similar mechanical properties, differences will show both in the roughness of the machined surface and in the magnitude of the cutting forces measured, which can be attributed to the influence of the microstructure of the workpiece material.This paper deals with the influence of the microstructure of Al alloys containing different amounts of silicon on the variation of the amplitude of the signal of the dynamic component of the main cutting force during fine turning. An analysis of the energy spectra and the auto-correlation functions of the amplitude of the dynamic component of the cutting force confirmed the relationship between the latter and the size of the phases in the microstructure of the workpiece material. It was confirmed that the microstructural changes were directly related to the amplitude of the cutting-force variation in the cutting zone. The microstructural changes and the cutting force can be considered as random phenomena; therefore, they may be described by statistical parameters such as the mean value, the standard deviation, and the coefficient of variation. The values calculated for the individual alloys differed considerably and confirmed a close relationship between the statistical values of the intercept lengths of the phases in the microstructure and the dynamic component of the cutting force.     

Control of mechanized surfacing of stamping tools with modulation of conditions

The results of investigations of the effect of the regulated parameters of low-frequency modulation on the characteristics of deposited beads in reconditioning of the working surfaces of dies of stamping tools are presented. The effect of the frequency and duty ratio of the modulated conditions on the mechanical properties of the deposited layer and the structure of its metal is described. Recommendations are issued for the effective application of technology with the controlled modulated conditions in the reconditioning of the working edges of the dies of the stamping tools.     

Properties of Mechanically Milled Nanocrystalline and Amorphous Mg–Y–Ni Electrode Alloys for Ni–MH Batteries

Nanocrystalline and amorphous Mg2Ni-type Mg20-xYxNi10(x = 0,1,2,3 and 4) electrode alloys were fabricated using mechanical milling.The effects of the Y content and milling time on the microstructures and electrochemical performances of the alloys were investigated in detail.X-ray diffraction and transmission electron microscopy analyses revealed that the substitution of Y for Mg yields an obvious change in the phase composition and micro morphology of the alloys.When the Y content x B 1,the substitution of Y for Mg does not change the major phase Mg2 Ni,but with a further increase in the Y content,the major phase of the alloys transforms into the YMg Ni4 YMg3 phase.A nanocrystalline and amorphous structure can be obtained by mechanical milling,and the amorphisation degree of the alloy visibly increases with increased milling time.Electrochemical measurements indicate that the discharge capacity of the alloys first increases and then decreases with increasing Y content and milling time.The substitution of Y for Mg dramatically ameliorates the cycle stability of the as-milled alloys,and the mechanical milling more or less impairs the cycle stability of the alloys.Furthermore,the high rate discharge ability,electrochemical impedance spectrum,Tafel polarisation curves and potential step measurements indicate that the electrochemical kinetic properties of the as-milled alloys first increase and then decrease with increasing Y content and milling time.