控制6A02-T6铝合金XC065型材粗晶环的工艺研究

热挤压6A02-T6铝合金型材出现粗晶环,试验研究在加热炉中加热铸锭的方式、加热温度和保温时间以及淬火加热制度对其粗晶环的影响,确定出合理的工艺参数,控制6A02-T6铝合金XC065型材不出现粗晶环或粗晶环深度在5 mm之内,以满足用户的使用要求。     

停放时间对2024铝合金挤压型材力学性能影响

在495℃固溶保温50 min和175℃时效保温10 h工艺条件下,研究了停放时间对2024铝合金挤压型材力学性能的影响。实验结果表明:在该工艺条件下,淬火后停放8 h进行时效处理,2024铝合金挤压型材的屈服强度、抗拉强度、断后伸长率均达到最大值。结合实际生产效率,2024铝合金挤压型材淬火后应在8 h内进行时效处理。     

固溶工艺对7A52铝合金型材组织与性能的影响

采用拉伸试验、组织观察等方法,探讨了固溶温度、保温时间和淬火转移时间对7A52铝合金组织与性能的影响。结果表明,7A52铝合金型材经470℃1 h固溶处理后残余相基本消除,480℃1 h固溶发生轻微过烧;随固溶温度的升高,合金强度先升高后下降,480℃时达到峰值;随着保温时间的延长,强度和伸长率均先升高后降低;随着淬火转移时间的延长,强度和塑性均降低,且转移时间60 s时的屈服强度较10 s的降低了约25 N/mm2。     

6063-T1型材屈服强度影响因素的探究试验

本文针对某6063-T1铝合金汽车用型材,试验验证致使型材屈服强度偏高的主要因素。结果表明,铸锭加热温度在450~480℃之间对6063-T1铝合金型材屈服强度影响较小,6063合金属淬火敏感性较低合金,淬火温度范围较宽,不同的淬火强度对型材屈服强度影响较小。随着停放时间的延长,屈服强度也随着增大,并且变化趋势较为明显。当拉伸率在0.8~1.0%时,保证型材在15天之内完成冲压加工,型材屈服强度符合要求,而且型材成品率较高,满足客户要求。     

2A70铝合金挤压型材生产工艺研究

介绍了2A70铝合金挤压裂型材生产工艺的研究情况。论述了2A70铝合金成分的控制范围、配料要求、熔铸工艺和挤压模具设计制造及修理技术，铸棒的均匀退火加热制度，挤压温度－速度、淬火、时效工艺参数的制定。通过对不同成分的2A70铝合金成分进行熔铸试验，在不同工艺制度下对2A70铝合金铸棒进行挤压试验，对2A70铝合金挤压型材进行不同工艺制度下的时效处理，最终研究出用于我厂生产的工艺制度。结果表明，采用此种工艺制度生产出了材料强度高、耐热性能好，用于生产现场后取得理想的效果。     

固溶时效处理对Al-4.0Cu-2.0Mg合金型材组织性能的影响

试验研究了固溶温度、保温时间、淬火转移时间、冷却水温及自然时效对Al-4.0Cu-2.0Mg铝合金型材组织和性能的影响,确定了合理的热处理工艺制度。结果表明,固溶温度为(500±5)℃、保温时间在15 min～30 min为适宜;淬火转移时间在15 s以内,冷却水温控制在20℃以内时,合金无晶间腐蚀倾向;自然时效时间大于4 d(96 h)时,该合金型材性能趋于稳定。     

2014铝合金板材热处理工艺研究

试验研究了退火温度、退火时间、淬火温度、淬火时间、时效温度和时效时间等因素对2014铝合金板材组织与性能的影响。确定了2014铝合金薄板各种热处理工艺参数:退火温度380℃,退火保温时间1 h;淬火温度500℃,淬火加热保温时间10 min;时效温度160℃,时效保温时间12 h。在工业生产条件下,采用以上确定的热处理工艺参数生产出O状态、T4状态和T6状态的薄板,其性能均完全达到标准中规定的指标。     

在线淬火工艺对6005A合金挤压型材组织与性能的影响

采用正交试验和模拟试验的方法, 研究了在线淬火方式、淬火冷却速度及淬火延迟时间对6005A铝合金空心型材组织和性能的影响. 结果表明 提高在线淬火冷却强度比提高挤压温度和挤压速度对改善型材性能的效果更明显, 型材强度随淬火冷却速度的增大明显提高, 而延伸率并无明显降低; 在线精密水雾淬火可使型材性能满足车辆型材使用要求; 缩短在线淬火前型材在室温环境下的停留时间, 可以显著提高型材强度性能.     

T2铜/2A50铝合金锻接扩散焊工艺及显微组织分析

采用锻接扩散焊法进行了T2铜／2A50铝合金异种材料的焊接。利用显微硬度、能谱分析（EDS）、扫描电镜（SEM）、X射线衍射（XRD）等测试方法对接头界面附近的显微组织进行分析。试验结果表明，T2铜／2A50铝合金，采用先锻接，后加热到515～525℃之间，保温180min，并在加热和保温过程中通过特殊的夹具提供给试样压力，能得到冶金结合的T2铜／2A50铝合金接头，接头界面处出现了明显的焊缝。     

铝合金长零件在空气循环炉内加热的特性

在工业上广泛地采用空气循环电炉加热各种铝合金零件。目前已经使用新结构的这种类型的炉子进行长铝合金半成品(型材、管材、板材等)的淬火。要遵照正确的铝合金热处理(特别是淬火)工艺规范,加热设备必须能保持一定的温度制度,精确度±2～±3℃,同时要保证加热迅速和均匀。利用空气循环炉在气流中加热     

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.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

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.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。