45钢渗硼工艺的正交分析研究

研究了渗硼温度、供硼剂种类、活化剂种类及其含量对渗硼层厚度和质量的影响，并对硼砂型渗硼剂中加入硅铁作为还原剂对渗硼效果的影响也进行了研究。结果表明：温度与供硼剂种类是45钢渗硼的主要影响因索；45钢渗硼的最优工艺方案为：供硼剂选用B4C 稀土，活化剂为Na3AlF6，活化剂含量为20％～30％，温度为950℃；以硼砂为供硼剂的渗硼剂中加入硅铁粉能提高渗硼层的厚度及渗硼质量。     

含稀土元素渗硼剂渗硼工艺试验

介绍一种含稀土元素廉价的固体渗硼剂，并对其进行了渗硼工艺试验。结果表明：采用该渗硼剂是可行的，且稀土可提高渗硼速率。     

LBI渗硼剂渗硼试验研究

介绍了使用一种廉价渗硼剂(LBI)在不同温度及保温时间下的渗硼试验。结果表明,采用LBI作渗硼剂是可行的,可获得连续、均匀、致密且无缺陷的渗硼层。     

固体渗硼的发展概况

1前言自Moisan发表第一篇钢铁的气体渗硼论文以来，渗硼工艺已有百余年历史，在以后的半个世纪中先后研究了气体、液体和固体法等多种渗础工艺。液体渗硼由于所用增损使用寿命短、工件表面粘盐不易清理及质量较难控制等问题，应用较少。气体渗硼和离子渗硼则因采用的BCI。、BZH。介质，有价格高、剧毒、易爆等问题，也未能用于生产。从60年代开始，人们又开始重视固体渗棚，研究内容侧重于寻找质量稳定、渗棚温度低、时间短、价格便宜的固体渗硼剂和渗硼工艺。前西德布莱梅硬化技术研究所，首先采用氟硼酸钾作为活化剂，将渗硼温度降低到…     

含稀土固体渗硼剂渗硼处理试验

本文介绍一种廉价含稀土固体渗硼剂，并进行了渗硼处理试验，通过渗层组织的观察和渗层硬度的测定以及渗硼剂重复使用性的探讨。结果表明：采用该渗硼剂可使钢件表面获得较好的渗硼层，且稀土可以提高渗层的质量。     

硼砂—石墨型粒状渗硼剂

1．前言硼砂型渗硼剂的应用结果表明，用廉价的棚砂取代B4C、B－Fe作为供硼剂是可行的[1～2]。本研究用含结晶水硼砂、石墨等廉价材料取代B4C、B－Fe、SiC和KBF4等较贵材料制作粒状渗硼剂，在大大降低成本的同时，提高渗硼速度和渗棚层质量以及渗后工件表面质量；45钢经950℃×6h的渗硼可得到大于300μm的致密渗硼层，使渗硼工艺能应用于承受强烈磨粒磨损的工件及难以渗硼的钢铁材料；由于渗速快，在较低的温度和较短时间内就能得到较厚的渗硼层，因此也能应用于变形要求严格的工件。本文同时对厚度大于300μm的渗硼层的耐磨性和耐腐…     

一种节能高效快速渗硼技术

介绍了一种以直流电场加速固体粉末渗硼的技术及其效果.采取在固体粉末渗剂中相对零件欲渗硼面放置板状电极作为电场正极,以需渗硼金属件作为负极.正负电极与渗硼剂装入渗箱中密封,置于箱式炉中加热,同时在需渗硼金属件与正极间施加一定的直流电场,即可实现快速渗硼.该法与现行固体渗硼相比,在700℃～900℃范围的不同温度,渗速至少可提高0.5～1倍.该技术提高固体粉末渗硼剂的利用率、减少处理能耗,还可降低渗硼温度.     

一种新的固体渗硼工艺

介绍一种廉价新型固体渗硼剂 ,并进行了渗硼工艺试验。结果表明 :采用该渗硼剂是可行的 ,可使钢件表面获得连续、均匀且无缺陷的渗硼层。     

中温渗硼应用

介绍了电影机上的导片片零件采用中温硼铝稀土多元共渗工艺,讨论了渗硼过程和渗剂成分、保温时间及淬、回火对渗层的影响。实践证明,中温渗硼零件变形小,成本低,工艺简单,渗硼后零件硬度和耐磨性能满足需要。     

固体气相渗硼工艺及设备

渗硼可在气体、液体及固体的供硼介质中进行。气体渗硼的优点是温度低、渗速快、工件变形小,但由于气氛有毒或易爆及价格昂贵,在实际应用中行不通。正如西德不莱梅硬化技术研究所所长泰基博士所断言:气体渗硼要用     

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。