45钢的瞬时液相扩散焊

采用自制的Fe-Si-B非晶合金箔作中间层，自制的保护层进行保护，对45钢进行瞬时液相扩散连接。分析了不同工艺参数下焊接接头的组织特征及显微硬度。研究表明：在合适的工艺参数下，研制的Fe-Si-B中间层可以实现45钢的瞬时液相扩散连接，接头组织和母材接近。     

45钢的瞬时液相扩散焊

采用自制的Fe-Si-B非晶合金箔作中间层,自制的保护层进行保护,对45钢进行瞬时液相扩散连接。分析了不同工艺参数下焊接接头的组织特征及显微硬度。研究表明:在合适的工艺参数下,研制的Fe-Si-B中间层可以实现45钢的瞬时液相扩散连接,接头组织和母材接近。     

T91/12Cr1MoV异种钢管TLP焊接工艺

采用BNi2非晶合金箔作为中间层,氩气保护,对T91/12Cr1MoV异种钢管进行瞬时液相扩散焊。通过正交试验的方法研究了工艺参数对接头组织和性能的影响,分析了T91/12Cr1MoV异种钢管接头的显微组织和力学性能,确定出最佳工艺参数。研究表明,在合适的工艺参数下,接头的抗拉强度均高于母材12Cr1MoV的。     

12Cr2MOV／TP304H异种钢管瞬时液相扩散焊工艺研究

采用氩气保护,用Fe基和BNi2合金箔作为中间层,进行了12Cr2MoV贝氏体耐热钢和TP304H奥氏体不锈钢管的瞬时液相扩散连接,分析了接头的力学性能、显微组织和断口特征,确定出了合适的连接工艺参数。研究表明,在合适的工艺参数下,用Fe基-BNi2-Fe基三层中间层连接的接头室温下的拉伸强度和弯曲强度等于或超过基体。     

12Cr2MoV/TP304H异种钢管瞬时液相扩散焊

采用氩气保护.用Fe基和BNi2合金箔作为中间层,进行了12Cr2MoV贝氏体耐热钢和TP304H奥氏体不锈钢管的瞬时液相扩散连接,分析了接头的力学性能、显微组织和断121特征,确定出了合适的连接工艺参数.研究表明,在合适的工艺参数下,用Fe基-BNirFe基三层中间层连接的接头室温下的拉伸强度和弯曲强度等于或超过基体.     

压力和保护气对开放环境下TLP连接接头的影响

用铁镍非晶合金箔作中间层,在大气环境下对T91耐热钢进行瞬时液相扩散连接,通过接头室温力学性能的测试以及弯曲断口形貌的扫描电镜观察分析,研究了连接压力、保护气对接头组织性能的影响.研究表明,连接压力有助于排除多余的中间层,施加保护气有助于液态中间层的净化;在双温工艺条件下,保护气压力0.3MPa,连接压力为6MPa获得的接头质量很好.     

耐热钢管的瞬时液相扩散焊工艺研究

用BNi2,Fe78Si9B13和FeNiCrSiB合金箔作中间层,氢气保护,分别对TP304和T91钢管进行了瞬时液相扩散(TLP)连接。分析了TLP连接接头的显微组织、力学性能和元素分布;确定出了合适的连接工艺参数。研究表明,TP304用BNi2和FeNiCrSiB作中间层,T91用FeNiCrSiB作中间层连接的接头室温下的抗拉强度和抗弯强度等于或超过基体。     

TP304钢管的瞬时液相扩散焊工艺研究

用BNi2、Fe78Si9B13和FeNiCrSiB合金箔作中间层．氩气保护，对TP304钢管进行了瞬时液相扩散焊。分析了其接头的显微组织、力学性能和元素分布，确定出了合适的连接工艺参数。研究表明，用BNi2和FeNiCrSiB中间层连接的接头室温下的拉伸强度和弯曲强度等于或超过基体。     

不同保温时间对T91/102异种钢管TLP连接接头组织和性能的影响

在开放式管道瞬时液相扩散焊机上对T91/102异种钢管进行TLP连接,采用氩气保护,在焊接温度1250℃、压力2/MPa、中间层选用LJ2(FeNiCrSiB)非晶合金箔固定不变的条件下,探讨保温时间对其TLP连接接头组织和性能的影响.结果表明,T91/102异种钢管TLP连接在其它工艺参数确定的条件下,最适宜的保温时间为3min.     

焊接温度对SIMP钢TLP连接接头组织与性能的影响

在氩气保护下,以BNi_2非晶合金箔作为中间层,对SIMP钢进行瞬时液相扩散连接,探究焊接温度对接头组织及性能的影响。结果表明,在焊接压力为8 MPa,焊接时间为3 min时,最佳焊接温度为1240℃。     

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。