Ti14合金半固态压缩中的应力松弛现象和变形机制的研究

利用Gleeble 1500热/力模拟机对Ti14合金进行了半固态压缩变形试验,研究了该合金在应变速率为5×10-2 s-1和5×10-1 s-1,变形温度为1273～1423 K条件下的流变应力变化规律,分析了该合金半固态下应力松弛发生的条件和原因,并讨论了温度、应变速率和变形机制之间的耦合关系.结果表明:温度和应变速率对流变应力有显著的影响,流变应力随着变形温度的升高和应变速率的降低而降低,宏观应力松弛发生在固相含量区间为0.95～0.98,主要是因为液相的增加减少了晶粒间的“固相桥”作用.由于液相在变形中的渗漏,Ti14合金在1273～1423 K半固态变形的应变速率试验值远远小于Iwasaki润滑流动机制(固液混合变形机制)所需的理论值,说明在所测试的半固态区间内合金仍以固相粒子变形为主,固液混合变形为协调机制.     

Ti14合金半固态压缩中的应力松弛现象和变形机制的研究

利用Gleeble1500热/力模拟机对Ti14合金进行了半固态压缩变形试验,研究了该合金在应变速率为5×10-2s-1和5×10-1s-1,变形温度为1273~1423K条件下的流变应力变化规律,分析了该合金半固态下应力松弛发生的条件和原因,并讨论了温度、应变速率和变形机制之间的耦合关系。结果表明:温度和应变速率对流变应力有显著的影响,流变应力随着变形温度的升高和应变速率的降低而降低,宏观应力松弛发生在固相含量区间为0.95~0.98,主要是因为液相的增加减少了晶粒间的"固相桥"作用。由于液相在变形中的渗漏,Ti14合金在1273~1423K半固态变形的应变速率试验值远远小于Iwasaki润滑流动机制(固液混合变形机制)所需的理论值,说明在所测试的半固态区间内合金仍以固相粒子变形为主,固液混合变形为协调机制。     

Ti14合金半固态压缩变形量对微观组织和流变行为的影响

利用Gleeble1500热/力模拟机研究了Ti14合金在应变速率为5×10-1s-1,变形温度1050、1100℃条件下,压缩变形量对合金半固态塑性变形行为和微观组织的影响。分析了合金流变应力与变形量之间的关系,探讨了变形量对合金微观组织尤变形过程中液相分布的影响,计算了不同温度和变形量的液相流动率。结果表明:合金在半固态条件下存在明显屈服现象,变形量的增加引起了流变应力的降低,其中变形量在50%~60%时,流变应力受变形量影响较大,随变形温度增加,变形量对流变应力影响减缓。分析认为:流动率是影响合金半固态流变行为的主要原因,变形量的增加引起了液相流动率的阶段性变化,其中,大变形量使得液相流动率增加,减缓应力集中,表现为较小的流变应力。     

Ti8LC合金热变形及其微观组织

采用GLEEBLE-1500热模拟机对Ti8LC合金在温度为850～1000 ℃、变形速率为0.001～0.1 s-1、最大变形程度为60%的条件下,进行恒应变速率高温压缩模拟试验研究,分析合金高温变形时流变应力与应变速率及变形温度之间的关系以及组织变化.结果表明:Ti8LC合金流变应力随应变速率的增大而增大,在恒应变速率条件下,真应力水平随温度的升高而降低;在给定的变形条件下,通过回归计算,建立了一种Ti8LC合金的本构方程;根据试验分析,在850～950 ℃温度时变形,主要发生动态再结晶,随着温度的升高,软化机制主要是动态回复.     

Ti60合金的流变应力行为及人工神经网络本构模型

采用Thermecmaster-Z型热加工模拟试验机对Ti60合金试样进行等温恒应变速率压缩试验,研究该合金在变形温度为600～950℃,应变速率为0.001～10s~(-1)条件下的流变应力行为,并构建人工神经网络(ANN)本构模型。结果表明,Ti60合金的流变应力随变形温度的升高和应变速率的下降而减小。在不同的变形条件下,Ti60合金的流变应力-应变曲线分别呈现流动稳态型和流动软化型两种特征。基于ANN所建立的本构模型预测精度高,流变应力试验值与预测值之间的相对误差在±5%以内,平均相对误差为1.82%,且相关系数趋近于1,能准确地描述并预测Ti60合金的流变应力行为。     

变形参数对含有少量液相Ti14合金压缩行为的影响(英文)

采用热模拟系统研究了半固态变形温度,应变速率和变形量对Ti14合金压缩行为和组织演变的影响。结果表明:温度和应变对Ti14合金半固态峰值应力影响较大,峰值应力随着温度的增加和应变速率的减小而降低。分析认为:半固态变形中,应变速率的变化会影响产生压缩变形所需的响应时间,而液相的含量受控于变形温度,随着变形温度的升高,组织中出现了网状晶界结构,使得变形机制由固相粒子的塑性变形转变为固液混合流动。此外,变形量对合金半固态变形的应力-应变影响较小,可以认为是液相的润滑作用和协调变形机制缓解了晶粒间的压缩应力和摩擦力,使得应力-应变变化不明显。     

Influence of Processing Parameters on the Deformation Behavior of Ti14 Alloy Containing a Small Volume of Liquid

采用热模拟系统研究了半固态变形温度,应变速率和变形量对Ti14合金压缩行为和组织演变的影响。结果表明:温度和应变对Ti14合金半固态峰值应力影响较大,峰值应力随着温度的增加和应变速率的减小而降低。分析认为:半固态变形中,应变速率的变化会影响产生压缩变形所需的响应时间,而液相的含量受控于变形温度,随着变形温度的升高,组织中出现了网状晶界结构,使得变形机制由固相粒子的塑性变形转变为固液混合流动。此外,变形量对合金半固态变形的应力-应变影响较小,可以认为是液相的润滑作用和协调变形机制缓解了晶粒间的压缩应力和摩擦力,使得应力-应变变化不明显。     

Cu-Ni-Si-Cr合金高温热压缩变形行为

采用Gleeble-1500D热模拟试验机,对Cu-Ni-Si-Cr合金在变形温度为600～800℃、应变速率为0.01～5 s-1条件下的动态再结晶行为以及组织转变进行了研究,分析了实验合金在高温变形时的流变应力和应变速率及变形温度之间的关系,并研究了在热压缩过程中组织的变化.结果表明:应变速率和变形温度的变化强烈地影响合金流变应力的大小,流变应力随变形温度升高而降低,随应变速率提高而增大,材料显微组织强烈受到变形温度的影响.     

Cu-Ni-Si-Ag合金动态再结晶及组织演变

在Gleeble-1500D热模拟试验机上,采用高温等温压缩试验,对Cu-2.0Ni-0.5Si-0.15Ag合金在应变速率为0.01～5s-1、变形温度为600～800℃、最大变形程度为60%条件下的流变应力行为进行了研究.分析了实验合金在高温变形时的流变应力和应变速率及变形温度之间的关系.并研究了在热压缩过程中组织的变化.结果表明:热模拟实验中,应变速率和变形温度的变化强烈地影响合金流变应力的大小,流变应力随变形温度升高而降低,随应变速率提高而增大.从流变应力、应变速率和温度的相关性,得出了该合金高温热压缩变形时的应力指数n,应力参数α,结构因子A,热变形激活能Q和流变应力方程.合金动态再结晶的显微组织强烈受到变形温度的影响.     

Cu-Ni-Si-P合金的动态再结晶

在Gleeble-1500D热模拟实验机上,在应变速率为0.01～5 /s、变形温度为600～800 ℃条件下,采用高温等温压缩实验对Cu-2.0Ni-0.5Si-0.03P合金的流变应力行为进行研究。结果表明：热模拟实验中,应变速率和变形温度的变化强烈地影响合金流变应力的大小,流变应力随变形温度升高而降低,随应变速率提高而增大;在应变温度为750和800 ℃时,合金热压缩变形流变应力出现明显的峰值应力,表现为连续动态再结晶特征。从流变应力、应变速率和温度的相关性,得出该合金热压缩变形时的热变形激活能和本构方程。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.