具有自动标定功能的激光焊缝跟踪系统研究

针对实际焊接过程中存在的纠偏量问题和焊枪振荡现象,在现有焊缝自动跟踪技术的基础上,通过采用激光视觉传感器、十字滑架和两个垂直布置的纠偏步进电机,对激光头与焊枪之间偏移角实现了自动检测和标定,由此提出了具有自动标定功能的激光焊缝跟踪系统,并开展了相应的试验研究。结果表明:所提出的激光焊缝跟踪技术除有效解决上述焊接过程中的问题外,焊缝的跟踪精度及焊接质量也得到了明显提高。同时,具有自动标定功能的激光焊缝跟踪系统,能使焊缝的跟踪误差控制在一个较小范围内,理想情况下跟踪精度可达0.13 mm,拓展了其在精密焊接领域中的应用。     

埋弧焊钢管焊缝相控阵超声自动检测方法探讨

为了解决埋弧焊管焊缝缺陷检测问题，针对埋弧焊管焊缝产生缺陷的特点进行探讨，分析缺陷成因及各类无损检测方法特点，采用相控阵超声自动检测方法，通过计算机仿真软件建立埋弧焊管焊缝截面模型并模拟声束全覆盖检测，设计模拟试块应用虚拟探头排列方式对各种缺陷(纵向、横向及热影响区)进行检测。结果表明：相控阵超声自动检测技术对埋弧焊管焊缝缺陷检测结果稳定可靠，能够有效指导埋弧焊管焊缝相控阵超声自动检测工艺设计，直观显示超声波束在焊缝中的覆盖状态，克服相控阵超声检测参数设置的盲目性，为埋弧管焊缝缺陷相控阵自动检测提供借鉴。     

液压支架缸体环焊缝缺陷超声自动检测技术研究

针对企业生产实际中液压支架缸体环焊缝质量检验这一技术难题,为了克服目前手动超声检测方式的缺点和不足,保证焊接质量,文章提出一种以数字超声探伤仪为基础,以计算机为核心,以现有自动焊接装置为工件装夹平台的液压支架缸体环焊缝超声自动检测系统,对该系统的总体设计、硬件组成、软件结构以及关键技术进行了详细地阐述,并对含有人工反射孔的缸体试样进行了超声检测实验研究.实验结果表明,该系统较好地实现了缸体环焊缝缺陷的自动化和图像化检测,为缺陷的自动定量检测和智能识别奠定了良好的基础.液压支架缸体环焊缝超声检测关键技术的研究和系统的进一步完善,将实现环焊缝检测的自动化、数字化、图像化、智能化,大大提高超声检测的效率和可靠性,从而有效控制液压支架缸体的焊接质量.     

焊缝缺陷X射线实时自动检测系统的图像处理

针对焊缝缺陷X射线实时自动检测技术普遍存在误检率与漏检率高的问题,研制了钢管焊缝缺陷X射线实时自动检测系统。研究了采用波形分析法与背景消除法信息融合进行焊缝缺陷检测的方法,从而有效降低了误检率与漏检率。该系统已用于西气东输钢管焊缝缺陷X射线实时自动检测。     

X射线焊缝图像的缺陷检测与识别技术

针对目前无损检测主要采用人工方式存在的主观不一致、检测效率低、操作复杂等问题,设计了一套焊缝缺陷自动检测系统。提出基于Otsu双阈值分割的缺陷区域自动提取、图像的降噪和灰度增强的图像预处理方法;通过SUSAN算法检测焊缝缺陷目标,并结合形态学孔洞填充算法修正缺陷目标;计算焊缝缺陷目标特征参数,并结合所设计的深度为4的二叉树分类识别逻辑流程,实现了较好的焊缝缺陷的检测结果。     

T型激光焊接接头近表面微小缺陷的自动超声波检测

给出了超声波自动检测过程中影响C扫描图像成像质量的各种参数,如探头的种类、水程、扫查灵敏度和闸门,并对设计和加工的模拟试件进行了超声水浸检测,获得焊缝中的模拟缺陷图像。与X射线照相图片对比结果表明,应用此方案检测T型钛合金激光焊缝时,可以发现在焊缝表面粗糙度较小的试件表面以下1.0~2.5 mm深处、直径>0.3 mm的缺陷。     

油气管道环焊缝自动超声检测与射线检测方法对比

针对AUT(自动超声检测)与RT(射线检测)检测管道环焊缝结果不一致的问题,结合AUT与RT检测原理,制作了校准试块及含人工缺陷焊缝,制定了AUT与RT检测管道焊缝试验方案,根据试验方案对人工缺陷焊缝进行了对比检测,在此基础上分析AUT与RT对管道环焊缝缺陷的检出率。结果表明:AUT对全自动焊产生的未熔合缺陷具有很高的检出率;RT检测自动焊环焊缝坡口时,若射线方向与未熔合缺陷方向一致,则检出率最高,但随着射线方向与未熔合缺陷角度的增大,检出率降低,容易漏检。     

管道环焊缝的相控阵超声检测

针对半自动焊及手工焊管道环焊缝相控阵超声检测(PAUT)提出了可靠性试验方法,设计制作了人工模拟自然缺陷,进行了PAUT、自动超声检测(AUT)等大量对比试验。通过宏观切片制作及样本统计学分析,建立了PAUT环焊缝缺陷检测的POD(Probability of Detection)曲线,以及定量能力评估的POS(Probability of Sizing)曲线,用实际数据分析了PAUT环焊缝检测的可靠性。数据结果表明,PAUT具有较高的检出率,95%置信度下达到90%检出率的缺陷尺寸为0.92mm。采用-6dB测高法得出的定量分析结果误差较大,误差平均值为2.94mm,误差标准差为1.37mm,定尺普遍偏大,离散性较大,定量方法仍需改进。     

焊缝磁粉检测图像自动分拣系统的设计与应用

定期对球罐等承压设备的焊缝进行磁粉检测是保障其安全的重要措施,发展基于爬壁机器人的磁粉检测系统是球罐自动检测作业的重要方向。爬壁检测机器人携带有视觉传感器,可实时采集磁粉检测结果。故,磁粉检测图像的快速自动缺陷分析是实现爬壁检测机器人的重要研究基础。通过图像像素分析法,对视觉传感器收集的实时图像进行自动识别,并将图像快速自动分拣归类到无缺陷、有缺陷及可疑图像等3个文件夹,以协助磁粉检测人员快速识别焊缝缺陷。     

具有遥控监视功能的焊缝自动跟踪图像处理系统

实现焊接过程自动化和机器人化，焊缝自动跟踪必不可少。本文对埋弧焊中焊缝自动跟踪系统的传感器、图像处理系统及遥控监视功能进行了研究，得到一种造价低廉且功能齐全的焊缝跟踪系统。     

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。