Deformation Behavior of Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo-0.35Si-0.85Nd Alloy in β/Quasi-β Forging Process

The hot deformation behavior of Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo-0.35Si-0.85 Nd alloy in β/quasi-β forging process was studied using isothermal compression tests over temperature range from 1040 ℃ to 1100 ℃ and strain rates form 0.001 s~(-1)to 70 s~(-1)The results show that the flow stress and microstructure are sensitive to thermomechanical parameters.The processing maps based on the dynamic materials model at strain of 0.3 and 0.7 were established.The optimum deformation thermomechanical parameters at a strain of 0.7 have two regions that exhibit the peak of power dissipation efficiency.One is the region of 1062-1100 ℃ and 10~(-3)-10~(-1.5)s~(-1); and another which represents dynamic recrystallization is 1040-1045 ℃ and 10~(-1.8)-10~(-0.9)s~(-1)The instable region is located where the strain rate is larger than 1 s~(-1)which corresponds to the mechanical instability.     

Effect of squeeze casting process on microstructures and flow stress behavior of Al-17.5Si-4Cu-0.5Mg alloy

The effects of squeeze casting process on microstructure and flow stress behavior of Al-17.5Si-4Cu-0.5Mg alloy were investigated and the hot-compression tests of gravity casting and squeeze casting alloy were carried out at 350-500°C and 0.001-5s-1.The results show that microstructures of Al-17.5Si-4Cu-0.5Mg alloys were obviously improved by squeeze casting.Due to the decrease of coarse primary Si particles,softα-Al dendrite as well as the fine microstructures appeared,and the mechanical properties of squeeze casting alloys were improved.However,when the strain rate rises or the deformation temperature decreases,the flow stress increases and it was proved that the alloy is a positive strain rate sensitive material.It was deduced that compared with the gravity casting alloy,squeeze casting alloy(solidified at 632 MPa)is more difficult to deform since the flow stress of squeeze casting alloy is higher than that of gravity casting alloy when the deformation temperature exceeds 400°C.Flow stress behavior of Al-17.5Si-4Cu-0.5Mg alloy can be described by a hyperbolic sine form with Zener-Hollomon parameter,and the average hot deformation activation energy Q of gravity casting alloy and squeeze casting alloy is 278.97 and 308.77kJ/mol,respectively.     

Hot workability of Mg-9Y-1MM-0.6Zr alloy

The behavior evolvement of Mg-9Y-1MM-0.6Zr (WE91) alloy during hot deformation process was discussed. The flow stress behavior of magnesium alloy over the strain rate range of 0.001 to 1 s-1 and the temperature range of 653 to 773 K was studied on a Gleeble-1500D hot simulator under the maximum deformation degree of 60%. The experimental results showed that the relationship between stress and strain was obviously affected by the strain rate and deformation temperature and the flow curves observed were typical of the occurrence of dynamic recrystallization. The flow stress of WE91 magnesium alloy during high temperature deformation could be represented by the Zener-Hollomon parameter in the hyperbolic Arrhenius-type equation. The average deformation activation energy Q and strain coefficient n were 224.11 kJ/mol and 3.08 by calculation,respectively. The processing maps were calculated and analyzed according to the dynamic materials model. The map at strain of 0.916 exhibited three domains with peak efficiency of 49%,44% and 42%,respectively. It was found that the alloy could be extruded at 693 K with mechanical properties of σ0.2=240 MPa,σb=315 MPa and δ=15.5%.     

Low-temperature superplasticity of ultra-fine-grained Ti-6Al-4V processed by equal-channel angular pressing

The low-temperature superplasticity of ultra-fine-grained (UFG) Ti-6Al-4V was established as a function of temperature and strain rate. The equiaxed-alpha grain size of the starting material was reduced from 11 to 0.3 μm (without a change in volume fraction) by imposing an effective strain of ∼4 via isothermal, equal-channel angular pressing (ECAP) at 873 K. The ultrafine microstructure so produced was relatively stable during annealing at temperatures up to 873 K. Uniaxial tension and load-relaxation tests were conducted for both the starting (coarse-grained (CG)) and UFG materials at temperatures of 873 to 973 K and strain rates of 5 × 10⁻⁵ to 10⁻² s⁻¹. The tension tests revealed that the UFG structure exhibited considerably higher elongations compared to those of the CG specimens at the same temperature and strain rate. A total elongation of 474 pct was obtained for the UFG alloy at 973 K and 10⁻⁴ s⁻¹. This fact strongly indicated that low-temperature superplasticity could be achieved using an UFG structure through an enhancement of grain-boundary sliding in addition to strain hardening. The deformation mechanisms underlying the low-temperature superplasticity of UFG Ti-6Al-4V were also elucidated by the load-relaxation tests and accompanying interpretation based on inelastic deformation theory.     

Constitutive Modeling for Flow Behaviors of Superaustenitic Stainless Steel S32654 during Hot Deformation

Hot deformation behavior of superaustenitic stainless steel S32654 was investigated with hot compression tests at temperatures of 950-1 250 ℃ and strain rates of 0.001-10s~(-1).Above 1 150 ℃,with strain rate lower than 0.1s~(-1),the flow curves exhibit nearly steady-state behavior,while at higher strain rate,continuous flow softening occurs.To provide a precise prediction of flow behavior for the alloy,the constitutive modeling considering effect of strain was derived on the basis of the obtained experimental data and constitutive relationship which incorporated Arrhenius term and hyperbolic-sine type equation.The material constantsα,n,Q and lnA are found to be functions of the strain and can be fitted employing eighth-order polynomial.The developed constitutive model can be employed to describe the deformation behavior of superaustenitic stainless steel S32654.     

Microstructural evolution and superplastic deformation behavior of fine grain 5083Al

The microstructural evolution during superplastic deformation of a fine grain Al-4.7 pct Mg alloy (5083Al) has been studied quantitatively. Starting from an average grain size of 7 μm, grain growth was monitored in this alloy both under static annealing and with concurrent superplastic deformation at a high test temperature of 550°C. Grain size was averaged from measurements taken in longitudinal, transverse, and thickness directions and was found to grow faster during concurrent superplastic deformation than for static annealing. A grain growth law based on an additive nature between time-based and strain-based growth behavior was used to quantify the dynamics of concurrent grain growth. The extent of void formation during deformation was quantified as the area fraction of voids on L-S planes. This void fraction, referred to as the cavity area percent, was recorded at several levels of strain for specimens deformed at two different strain rates. A constitutive equation incorporating this grain growth data into the stress-strain rate data, determined during the early part of deformation, was generated and utilized to model the superplastic tensile behavior. This model was used in an effort to predict the stress-strain curves in uniaxial tension under constant and variable strain rate conditions. Particular attention was paid to the effects of a rapid prestrain rate on the overall superplastic response and hardening characteristics of this alloy.     

Constitutive model and deformation microstructure of fine-grain Mg-Zn-Y alloy solidified under high pressure

Fine-grain Mg_(95.50)Zn_(3.71)Y_(0.79) alloy was prepared by high pressure solidification.By comparison with the conventional casting alloy,the true stress-strain curve characteristic and deformation microstructure of Mg_(95.50)Zn_(3.71)Y_(0.79) alloy solidified under high pressure were studied via unilateralism compress tests under the strain rate of 0.001–1 s~(–1) and deformation temperature of 523–623 K.Constitutive equations were constructed.According to the experimental results,compared to the conventional casting alloy,the true stress-strain curve of the fine-grain alloy solidified under high pressure not only had the high strain hardening characteristic but the dynamic recrystallization softening after the peak stress was more than the working hardening and would soon reach a stable flow stress- strain state.The deformation activation energy of the alloy solidified under high pressure was 151 kJ/mol,around 49 kJ/mol lower than that of the conventional casting alloy.The fine-grain Mg-Zn-Y alloy solidified under high pressure could obtain 95 percent of dynamic recrystallization grain at 573 K during hot deformation process.     

Study on the Deformation Behavior of Mg-3.6% Er Magnesium Alloy

The deformation behaviour of a casting Mg-3.6% Er magnesium alloy after T6 treatment was studied in tensile tests from room temperature to 450 ℃ under different strain rates ranging from 1.0 ×10^-4 to 6.0 × 10^-3 S^-1 Obtained local plateau in the temperature dependence of the ultimate strength （σb） and yield strength （σ0.2） under constant strain rate indicated the presence of dynamic strain ageing （DSA）. Serrated flow was observed at the temperature of 200, 250, and 300 ℃. The observed negative strain rate sensitivity suggested that the serrated flow behavior arose from DSA. The temperature and strain rate dependence of the critical strain for the onset of serrated flow was analyzed using a phenomenological DSA equation, and the apparent activation energy Q for the serrated flow was obtained by calculation.     

Effect of Initial Microstructure on Warm Deformation Behavior of 45 Steel

 In order to investigate the effect of initial microstructure on warm deformation behavior, some specimens of 45 steel were annealed and some quenched. Then the specimens were isothermally compressed on a Gleeble 3500 machine. The deformation temperature range was 550 to 700 ℃ and the strain rate range was 0.001 to 0.1 s-1. An optical microscope (OM) and a transmission electron microscope (TEM) were used to study the microstructures. The results show that the microstructure of annealed specimens is ferrite and pearlite and that of quenched specimens is martensite. The flow stress of quenched specimens is higher than that of annealed ones at 550 ℃ when strain rates are greater than 0.001 s-1. However, at 600 to 700 ℃ and strain rate of 0.001 s-1, the whole flow curves of quenched specimens are below that of annealed ones. Under the rest conditions, the flow stress of quenched specimens is higher at the beginning of compression and then the opposite is true after the strain is greater than a critical value. The microstructure examination proves that the tempering and dynamic recrystallization easily occur in the specimens with martensite during warm compression, which results in the above phenomena.     

Design for Isothermal Forging of Ti-46.5Al-2.5V-1.0Cr-0.3Ni Alloy

 Abstract: The three-dimensional finite element code was utilized to investigate the isothermal forging of Ti-46.5Al-2.5V-1.0Cr-0.3Ni (at.%). The partition of height reduction, effective strain and damage during the forging were analyzed. And the experiment was employed to verify the simulation results. The results show that severe plastic deformation can improve the homogeneity of the deformed microstructure and the higher accumulative height reduction can be achieved through two-step forging. With the isothermal forging of 60%+62.5% (total 85%), the entire forged pancake can acquire refined microstructure and expand the uniform flow zone to almost the entire volume without generating strain-induced defects or cracking.     

Acceleration of Electricity Reform Brings Benefit to Big Electricity Users,Aluminum Manufacturers Can Save Costs Up to Several Hundred Million

<正>Recently the National Commission of Development and Reform again assembled experts to solicit opinions,and discussed new electricity reform program.According to information disclosed by experts attending the meeting,in the future electricity reform will undergo top-down design,possibly a     

Qinghai's Aluminum Processing Capacity to Rise at the End of the Year

正Since the release of Implementation Opinions on Carrying out‘Guiding Opinions of the State Council on Resolving Serious Production Overcapacity Conflicts’,according to the actual situation of industry,Qinghai has focused on electrolytic aluminum,cement,ironsteel(including iron alloy and silicon carbide),     

Recent Trends in China's Copper Scrap Market-Part Ⅱ

<正>2.Tianjin Scrap Metal Market In Tianjin,we mainly visited Jinghai Ziy Town scrap market and Binhai New Area’some copper scrap enterprises and enterprise using copper scrap.In Ziya we felt the coppe scrap market was particularly deserted,mos copper scrap enterprises in the town wer closed,industry insiders said in 2012 the plac here was bustling with activity.According to     

Shanghai Clearing House to Roll out Renminbi-denominated Copper Clearing Operations in Free Trade Zone

正Clearing House Financial Markets Co.,Ltd.(Shanghai Clearing House)General Manager Xie Zhong told the media recently at the briefing of the international symposium of"Reform Deepening and Mechanism Innovation of the Post-crisis Kerb Market",Shanghai Clearing House will explore the feasibility of carrying out bond business in     

Development and Application of New Materials for Copper Processing in China

正After over 60 years of developmnt,a system for RD and production of copper processing materials has already taken shape in China.After the reform and opening-up,the application of copper processing materials has gradually expanded from the military industry to civil field.The annual output of copper     

China’s Mineral Exploration Market Downturn Causes Decline of Investment in Bauxite

<正>According to a survey report conducted recently by China Geological Survey Development Research Center,in the first half of 2014,China’s mineral exploration market continued to decline,with the investment in exploration of non-fuel minerals dropping by13.7%and drilling workload dropping by21.7%.According to statistical analysis of the Center,     

Chinalco and China National Administration of Coal Geology Jointly Built Guangxi Rare Earth Industrial Base

正On June 3,Chinalco and China National Administration of Coal Geology signed cooperation agreement for strategic cooperationcooperation agreement between Chinalco Guangxi Nonferrous Rare Earth Development Company and Xuzhou Jin Shi Pengyuan Rare Earth Material Factory.According to the agreement,both sides would jointly support Chinalco Guangxi Nonferrous Rare Earth Development Company and Xuzhou Jin Shi Pengyuan Rare Earth Material Factory to carry out comprehensive cooperation covering rare     

Aluminium Production by Province or City in 2014

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Fabricated Copper Production by Province or City in 2014

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Zinc Production by Province in 2014

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