焊接接头超声检测中焊角伪缺陷回波的判别

本文针对焊接接头超声检测中焊角伪缺陷回波产生的原因、部位进行了论述并对其产生的规律性、特点以及如何判别焊角伪缺陷回波的方法进行了分析和探讨。     

Ultrasonic testing technique for small-calibre piping containing defects

An effective method of ultrasonic testing was developed for inspecting the quality of weld seams for small-calibre, thin-walled pipes. The basic technical problems encountered in measuring the height of defects in the piping by an ultrasonic testing method were analyzed and studied experimentally. To overcome these problems, two small probes with special cylindrical contact surfaces, and five types of piping contrast specimens were machined, and a corresponding quantitative scaling method was developed. Some preliminary data obtained by the proposed method and a practical measurement method were presented. These results show that the proposed method is also effective in determining the shape of defects in welded steel pipes, and has been directly used in the structural integrity assessment of pressure vessels and piping containing weld defects in a petrochemicals plant.     

International Institute of Welding work on residual stress and its application to industry

This paper gives an overview of the International Institute of Welding (IIW) activity on residual stress and distortion prediction (RSDP) in welded structures. The overall goal of the activity is to define an IIW recommendation for prediction and determination of welding residual stress and distortion. The three main collaborative activities that were launched to support this goal (a modelling round robin, a measurement technique benchmark and definition of a compendium) are described. It is concluded that significant progress has been achieved by participants to improve the modelling approaches, and to optimize experimental technologies to calculate and measure accurately the residual stress distribution and distortion in welded assemblies.     

Noise analysis of digital ultrasonic system and elimination of pulse noise

In the evaluation of a welded joint using a digital ultrasonic system, it is found that it is noise that constitutes the main difficulty in the detection of weak ultrasonic signals. In this work a physical model of a digital ultrasonic system is established and applied to analyze noises encountered in ultrasonic testing. An algorithm of extremum filtering is constructed to suppress the pulse noise. Experiment verifies that the algorithm is simple and efficient, and not only can it eliminate the pulse noise substantially, but it also retains the other components of the signal unchanged.     

超临界／超超临界锅炉新型铁素体耐热钢焊接质量控制

本文简要的介绍了在超临界／超超临界锅炉中广泛应用的新型铁素体耐热钢的发展历程、分类，对如何控制新型铁素体耐热钢焊接质量进行了分析，并对新型铁素体耐热钢焊接与传统低合金耐热钢焊接的不同点．新型铁素体耐热钢焊接的合格标准以及质量检验的相关要求进行了描述。     

Effect of the weld groove shape and pass number on residual stresses in butt-welded pipes

This study used finite element techniques to analyze the thermo-mechanical behaviour and residual stresses in butt-welded pipes. The residual stresses were also measured in some welds by using the Hole-Drilling method. The results of the finite element analysis were compared with experimentally measured data to evaluate the accuracy of the finite element modelling. Based on this study, a finite element modelling procedure with reasonable accuracy was developed. The developed FE modelling was used to study the effects of weld groove shape and weld pass number on welding residual stresses in butt-welded pipes. The hoop and axial residual stresses in pipe joints of 6 and 10 mm thickness of different groove shapes and pass number were studied. It is shown that these two parameters may have significant effects on magnitude and distribution of residual stresses in welded pipes.     

Continuum damage mechanics analyses of type IV creep failure in ferritic steel crossweld specimens

A major high temperature failure mechanism for weldments in ferritic steel steam pipework is circumferential creep cracking within the region of the heat affected zone, adjacent to the parent material, that experiences the lowest temperatures during the welding process. This is commonly known as type IV cracking. In recent years a number of experimental studies have investigated the occurrence of type IV failure in laboratory test pieces, however, there have been few attempts at theoretical modelling of type IV failure to assist in the formulation of design and assessment procedures. This report discusses the use of the creep continuum damage mechanics method for the analysis of the deformation and failure of weldments that are known to fail within the type IV region.The creep behaviour of each of the material regions of a weldment is described with a set of physically based constitutive equations, which incorporate a number of state variables. The finite element creep continuum damage mechanics method is used, with the physically based constitutive equations, to analyse the deformation and failure of the welded testpieces. The computations are shown to be in good agreement with the experimental results. The implications of the analyses are discussed with reference to the assessment of weldments that are susceptible to type IV failure.     

The behavior of welded joint in steel pipe members under monotonic and cyclic loading

Most steel pipe members are joined by welding. The residual stress and weld metal in a welded joint have the influence on the behavior of steel pipes. Therefore, to accurately predict the behavior of steel pipes with a welded joint, the influence of welding residual stress and weld metal on the behavior of steel pipe must be investigated.In this paper, the residual stress of steel pipes with a welded joint was investigated by using a three-dimensional non-steady heat conduction analysis and a three-dimensional thermal elastic–plastic analysis. Based on the results of monotonic and cyclic loading tests, a hysteresis model for weld metal was formulated. The hysteresis model was proposed by the authors and applied to a three-dimensional finite elements analysis. To investigate the influence of a welded joint in steel pipes under monotonic and cyclic loading, three-dimensional finite elements analysis considering the proposed model and residual stress was carried out. The influence of a welded joint on the behavior of steel pipe members was investigated by comparing the analytical result both steel pipe with a welded joint and that without a welded joint.     

Elastic-plastic FE calculations for a fracture mechanics analysis of a weld in the ligament of a CT specimen

Results of elastic-plastic FE calculations on four plane strain models of a CT-100 specimen, (a) with a weld in the ligament, (b) of base material only, (c) of welding simulated material only and (d) of weld material only, are compared and discussed in the light of fracture mechanics aspects. Regarding the cleavage fracture regime, considerably higher crack opening stresses are obtained in the welded specimen than in the base material specimen, as soon as small-scale yielding occurs. Conservative evaluation of the crack opening stresses of the welded joint can be achieved by using the welding simulated material properties. The J-integrals determined by the energy release rate using the method of virtual crack extension are equal for the four material models up to about 200 N mm⁻¹. Above this level, the behaviour of the welded specimen and that of the base material model are still similar, while a higher force is necessary for the welding simulated material model and the weld material model to reach the same J-value as for the two others. The crack opening profile of the welded specimen is asymmetric to the fusion line which lies in the ligament. The half profile of the heat-affected zone side is comparable to that of the welding simulated material model and the half profile of the weld material side to that of the base material model. A higher maximum of the equivalent strain on the heat-affected zone side than on the weld material side may explain why cracks tend to run into the base material region of the weld under conditions of stable crack growth. General yield of the welded specimen occurs on the base material side, whereas on the weld material side only a small plastic zone is visible, comparable to that in welding simulated material at the same load.     

Optimization of girth welded joint in a high-pressure hydrogen storage tank based on residual stress considerations

The cylinder sections in a high-pressure hydrogen storage tank are usually connected by girth welded joints. However, due to the ultra-thick wall of the cylinder, the weld geometry has a significant influence on the residual stress distributions, which are very difficult to be fully determined by experimental methods. Therefore, in this paper, four sequential coupling two-dimensional (2D) axisymmetric finite element (FE) models with different weld geometries have been developed to study the effects of weld groove shape on the residual stresses. In addition, the effects of working pressure (75 MPa) on the welding residual stress distributions have been investigated. The results demonstrate that different weld groove shapes bring different residual stress distributions, leading to different influences on structural integrity. Among the four types of welded joints, V and U types have similar residual stress distributions, and X and d-U types have similar distributions, but the latter two types have large tensile residual stresses at their inner surfaces, which have a greater risk of generating hydrogen induced cracking (HIC). After introducing a working pressure of 75 MPa, the welding residual stresses are redistributed, and the weld regions of the four types of welded joints are all fully yielded and plasticized. Based on the residual stress considerations, using V-shape groove can obtain the best residual stress distributions in an ultra-thick girth welded joint, which provides a reference for the welding and fabrication of a high-pressure hydrogen storage tank.     

Code characterisation of weld residual stress levels and the problem of innate scatter

Economic and safe management of operating nuclear power plant is increasingly dependent upon structural integrity assessments for pressure vessels and piping. The residual stress distribution assumed in defect assessments for welded joints often have a deciding influence on the analysis outcome. Guidance on characterising conservative levels of weld residual stress can be found in structural integrity codes and procedures such as R6, API 579 and BS7910. There is an increasing need to develop more realistic and reliable residual stress distributions that will deliver more accurate integrity assessments. However, future development of such distributions will have to deal convincingly with what is often termed the “innate scatter” of weld residual stresses. This paper first identifies and illustrates some of the origins of apparent innate scatter. The stability of the welding process is examined. The importance of transient weld bead starts/stops and the lay-up of passes in multi-pass welds are demonstrated. Uncertainties associated with two commonly used residual stress measurement techniques are reviewed and simple quantitative studies used to reveal the role of measurement gauge length and, more significantly, errors in spatial location on the level of measured residual stress. The final part of this paper surveys how structural integrity codes and procedures currently characterise welding residual stresses for defect-assessment purposes and discusses the development of more realistic residual stress profiles based on statistical treatment of scatter and uncertainties.     

The NeT bead-on-plate benchmark for weld residual stress simulation

Fracture mechanics based structural integrity assessments of pressure vessels and piping are widely used to support the economic and safe management of operating engineering plant. Assessments of defects at weldments can be highly sensitive to the through-thickness distribution of residual stress assumed in the fracture calculations. Increasingly, finite element modelling approaches are applied to predict residual stress in engineering structures arising from the welding process. However, such methods are complex and require analysts to make many assumptions and approximations. Guidelines covering the calculation of residual stresses in weldments are being prepared for inclusion in the R6 defect assessment procedure and will be accompanied by a series of validation benchmarks. The benchmarks will allow analysts to evaluate and improve the accuracy of weld modelling approaches and assess their suitability for use in fracture assessments. The first part of this paper presents an austenitic stainless steel bead-on-plate weldment validation benchmark based on the extensive round robin measurements performed by members of the European NeT project. The benchmark defines thermal and residual stress performance targets against which a weld simulation approach can be evaluated. Guidance is also provided on how to validate predicted residual stress profiles for use in a high integrity fracture assessment. The second part of this paper provides a commentary on how the weld simulation accuracy and performance targets have been established.     

0Cr18Ni10Ti与（SA387Gr11c12＋堆焊层）异种钢的焊接工艺

针对产品加强管（0Ci118Ni10Ti）与筒体（SA387Gr11C12＋堆焊层）角焊缝异种钢焊接接头焊接问题，提出了先在筒体开孔厚度上焊接隔离层，然后再焊接角焊缝实践证明，采用这种焊接工艺进行焊接，可以获得优良的焊缝，能够保证设备的正常运行、     

Creep deformation,rupture and ductility of Esshete 1250 weld metal

Abstract

Esshete 1250 is an austenitic steel with high creep strength and is well established as a superheater boiler tube material in UK power stations. In addition, Esshete 1250 is readily welded with either inert gas welding or metal arc welding and has been used for piping and headers in super critical power stations. The latter thick section components are either solution heat treated after welding or enter service in the as-welded condition. Components that enter service in the as-welded condition contain high residual stresses, which pose a threat to the structural integrity of these welds. In order to perform life assessments of as-welded Esshete 1250 welds, it is necessary to have data on the creep deformation, stress relaxation, rupture and ductility of the weld metal, which are described in this paper.     

对于厚度70mm〜140mm焊缝超声检测的讨论

超声检测作为一种面积型缺陷的有效检测方法,被广泛应用在气化炉、除氧器、汽包等的焊缝检测上。随着近年来电厂、化工厂对质量的要求提升,确保焊缝质量就成了生产制造厂的重点。对于这些重型容器,焊缝厚度普遍在70mm~140mm,在这个厚度区间,采取的多道焊接,工艺控制不严很容易产生缺陷。无损检测标准的制定只是简单的对此厚度划分两个区间,并未给出划定此区间的依据。本文通过实际检测气化炉、除氧器、汽包等焊缝来讨论超声检测在厚度70mm?140mm区间的划定依据。     

Automatic welding of pipeline in Japan: Part 2—The development of a method for the branch pipe joint in ship pipeline

The pipelines used in a ship amount to tens of thousands of metres per ship, and so automatic welding of the pipelines has been widely applied from the viewpoint of saving labour. In most cases the automatic welding process has been used for the welding of butt-joints which can be applied to the pipes in rotary motion, and it has also been used for fillet-welding of the connection between flange and piping. In the butt-welding of fixed pipings, automatic welding processes are now being partly used for position welding but up to the present time automatic welding has seldom been applied to the various types of branch pipe joints in which the welded lines form three-dimensional curves.In recent years, great progress has been made in the technique of constructing steel pipe structures and in the development of practical gas cutting processes to prepare the curves needed for the various welded joints used in piping. This paper deals with various conditions and performance requirements needed for automatic welding, such as the selection of shapes of prepared edges of pipings to be welded, the control of welding positions, the control of welding torches in operation, and the solution and control of other production variables.     

D151焊接型高中压外缸的焊接工艺研发

介绍了制造D151高中压汽缸采用焊接的背景,并详细阐述了针对焊接型汽缸所进行的焊接工艺的研发,如:为装配和防变形需要而设计制造的平台、专用预热和中间热处理设备等。在实际制造过程中还对最初的坡口设计存在的不足作了相应调整,最后对汽缸焊后的变形和无损探伤进行了说明,并提出了焊接方法改进的设想。     

Recent experience in pressure vessel materials irradiation

The reactor pressure vessel has been repeatedly cited as a primary concern in assessment of pressure boundary structural integrity and in planning for plant life extension programs. The life of the reactor pressure vessel will be limited by radiation-induced embrittlement; this is monitored in Westinghouse designed nuclear steam supply systems by testing samples of base metal, heat-effect-zone and weld metal in the form of Charpy V-notch, tensile, and fracture mechanics specimens which have been irradiated in surveillance capsules adjacent to the wall. The earliest reactor vessel material radiation surveillance program was the Yankee Rowe program which started in 1961. As data became available from power reactor surveillance and test reactor programs, estimates of radiation-induced changes in mechanical properties were predicted in the form of radiation damage trend curves which provide methods for calculating numerical estimates of changes in mechanical properties as a function of chemistry and fluence. For example, the proposed Revision 2 to Regulatory Guide 1.99 provides estimates of shifts in transition temperature as a function of copper and nickel content and fluence. Slight variations in chemical analyses for copper and/or nickel can result in limitation on heat-up and cool-down rates or compliance with regulatory rules, such as the PTS screening criteria. Automatic submerged arc welding was employed in the fabrication of reactor vessels in Westinghouse designed nuclear steam supply systems. The type of flux material utilized in the welding process is important because mechanical properties can differ depending upon what flux is used. This paper correlates the results from over 50 surveillance capsules with the welding practice and concludes that radiation damage trend curves can be developed for welding practice. By using trend curves based on welding practices, discrepancies in chemical analyses are eliminated and credibility is restored to structural integrity assessments.     

异种钛合金TIG焊接接头的组织和性能

本文针对800MPa级的Ti6A14V和600MPa级的∏T3B钛合金板材，选取与∏T3B匹配的2B焊丝，并采用手工钨极氩弧焊的方法进行焊接。焊后对接头的力学性能进行了测试，同时对接头的不同部位进行了显微组织观察和硬度试验试验结果表明：拉伸试样断裂在∏T3B母材，即采用低强度等级的焊丝焊接，由于Ti6A14V合金元素向焊缝的过渡，焊接接头的强度高于∏T3B板材的强度；显微组织观察发现焊缝中心形成了大量的针状马氏体组织；显微硬度试验中发现靠近∏T3B一侧的焊接接头熔合线附近由于晶粒长大，其硬度值较低，     

Influence of convection and grain movement on globular equiaxed solidification

A two-phase volume averaging model was used to study convection and grain movement, and their influence on the globular equiaxed solidification. Both liquid and solid phases were treated as separate interpenetrating continua. The mass, momentum, species and enthalpy conservation equations for each phase and a grain transport equation were coupled. An ingot casting (Al-4 wt.% Cu) with near globular solidification morphology was simulated. Case studies with different modeling assumptions such as with and without grain movement, and with slip and non-slip boundary conditions for solid phase were presented and compared. Understanding of grain evolution and macrosegregation formation in globular equiaxed solidification was improved.