大直径ERW直缝焊管排辊成型的有限元模拟

采用大型非线性有限元软件Marc对ERW直缝焊管的排辊成型过程进行模拟．获得了成型管坯形状以及各机架截面处和沿板带纵向的等效应力与应变场分布;分析了排辊成型面与管坯的接触状态。为排辊成型焊管机组的孔型设计以及排辊调整提供了理论依据。     

螺旋焊管机组辊式预弯边装置的孔型设计——螺旋焊管成型用带钢纵向边缘预弯曲率的近似计算

在螺旋焊管生产过程中,带钢纵向边缘预弯对预防和控制焊管成型缝产生"桃形尖"缺欠非常重要。介绍了一种辊式预弯边装置的孔型设计方法,给出了带钢弯曲成型时的边部翘曲曲率的计算公式,建立了带钢边部在辊式预弯边装置中的预弯曲率(指中性层)1/ρ预的数学模型,为二辊式预弯边装置的预弯辊辊型设计和三辊式预弯边装置的预弯调整指明了方向,对改善螺旋焊管成型缝质量和实际生产都具有一定的指导意义。     

螺旋缝埋弧焊管外观质量缺欠的产生原因及应对措施

螺旋缝埋弧焊管的外观质量与其内在质量一样,是影响焊管整体质量的重要因素.分析了螺旋缝埋弧焊管外观质量缺欠的产生原因,包括成型缝“噘嘴”,管体凹槽、压痕、压坑、划伤,焊缝外观质量欠佳等,提出了有效的预防、改善措施.     

ERW直缝焊管成型装置的发展

简要介绍了ERW直缝焊管成型装置的产生和发展历程。详细阐述了ERW直缝焊管排辊成型的特点、主要生产工艺布置和设备组成、排辊成型的换辊与调整等。     

国内外直缝焊管机组的发展趋势

探讨了国内外直缝焊管机组的发展趋势。重点讨论了辊式成型与排辊成型两种成型方式的特点．分析了国内引进的10余套ERW直缝电阻焊管机组的生产情况及工艺设备问题。指出除高（中）频热处理、超声波探伤、剪切对焊及排辊成型等设备可以引进外,飞切机、水平螺旋活套、水压机和平头倒棱机等都可以实现国产化。     

小直径高厚径比螺旋缝焊管的制造难点与解决措施

分析Φ219 mm×8 mm(Q235B)小直径高厚径比螺旋缝焊管在生产过程中出现的成型、焊接难点——错边、成型缝"噘嘴"、裂纹和内焊工装安装空间小及焊缝外观形貌控制难等问题,并提出改进措施。分析认为:缩短机臂前端第一个小辊与递送边的距离至60~110 mm,增加1号与3号梁的中心距,合理设置2号梁压下量等,可减少错边;优选成型角在46°~60°,立辊辊面锥角在2°~3°,增加单个轴承辊单侧高度等,可减少成型缝"噘嘴";降低残余应力,减少钢管成型过程中的前进阻力及带钢边缘挤厚量等,可减少裂纹。     

螺旋缝埋弧焊管成型工艺参数的优化控制

详细阐述螺旋缝埋弧焊管成型工艺参数的确定,分析1～3号成型辊位置调整的原因及调整的依据及计算方法,并将计算值与实际测量值进行比较。分析认为:螺旋缝埋弧焊管成型工艺参数调整的计算方法合理,理论计算值与实际测量值相差不大,计算准确,能在实际生产中应用。     

直缝焊管的W弯曲成型方法

<正> 在直缝焊管的生产工艺中,成型方法对焊管质量有重要影响。为了不断提高焊接速度及市场对焊管品种规格的需求,焊管生产厂对成型方法和孔型设计的要求越来越高了。中小直缝焊管的辊式成型分类,按成型过程中带钢边缘的横向运动轨迹分,有圆周弯曲法、边缘弯曲法、中心弯曲法、组合弯曲法等;按成型辊的排列方式分,有一般连     

直缝电焊钢管双半径成型孔型设计

根据某厂要求,我们在φ101～173焊管机组上采用了双半径成型法,设计了φ101～1.7毫米焊管成型机孔型,经过正式试车生产,成型效果较单半径的好。本文介绍了这种成型方法的特点;管坯成型孔型的设计方法;成型辊辊型设计;立辊孔型半径与辊型计算。文后给出了成型孔型设计实例。     

大中口径直缝焊管的排辊成型工艺

简要介绍了我国管道运输概况,大中口径焊管的市场需求及其制造业现状。较详细地比较分析了当今几种大中口径直缝焊管成型工艺,提出在我国建设大中口径直缝埋弧焊管机组时排辊成型工艺是可以推荐的机型方案之一。     

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。