Welding Procedure Specification Research Articles

WPS Design of Dissimilar Metal Welds between Austenitic Stainless Steel and Carbon Steel for Building Thermal Power Plants

Dissimilar metal welding (DMW) is frequently used to join stainless steels to other metals in Thermal Power Plants (TPP) and industries. DMW process has been shown to have great advantages for many years. This approach is most often used where a transition in mechanical properties and/or performance in service are required. The objective of this research is to review the basic principles of fusion welding of dissimilar metals.In experiments, the two seamless pipes with 18 mm thick, one modified SS 304L austenitic stainless steel was welded to another modified carbon steel A 106B by means of shielded metal arc (SMAW) and gas tungsten arc (GTAW) welding processes using ER309L and E 309L-16 type of filler metal. Before welding, essential variables were analysed so that creating preliminary welding procedure specifications (pWPS). After welding, weldment was tested by NDT such as visual, penetrant and radiography. Microstructural examinations were carried out including macro and micrographs, grain size analysis, and hardness measurements. Transverse tensile, and face/ root bend testing were carried out. Finally, WPS was established conformance to standards of TPP structure toward to building Nuclear Power Plant in Vietnam.

Algorithms of mathematical models for fast multi-pass weld-bead drawing technique in V-groove welding

This study proposes an algorithm by using bead sequences and drawing techniques for multi-pass V-groove welding. Several points were prepared to form the weld bead shape. Then, a spline method called piecewise cubic Hermite interpolation was applied to describe the smooth curve shape of the multi-pass weld beads in Cartesian coordinates. This study simply considers the physical behavior of weld pool, such as surface tension, to describe the bead shapes differently along the layer position bead sequence. These techniques are useful to improve the welding procedure specification and thus reduce the time consumed in drawing the bead shapes to 1 s for thick-plate welding process.

Scale down Approach to Solve Distortion Problem in Case of Wind Turbine Tower Fabrication

Submerged arc welding (SAW) process is extensively used in major industrial application such as wind turbine towers and ship building industries for joining of larger thickness (~10 to 50mm) of similar and dissimilar materials. However, other joining processes are not popular to weld larger thickness compared to SAW. In welding, one of the major problems is distortion, which destroys the dimensional stability of the component, a major concern in manufacturing. Simulation of larger thickness component will increase the simulation time. Therefore, an attempt has been made to evaluate a 3 - dimensional finite element analysis (FEA) using SYSWELD to study the effect of the joining of two similar shells of High Strength Low Alloy (HSLA) steel through scale down model in the ratio of 10:1. To reduce the simulation time, the two shells of steel having 400mm diameter and 2mm thickness are modelled and simulated with single pass GMAW process using eight different welding sequences as per welding procedure specification (WPS) using SYSWELD. Results show the simulated welding sequence no. 4 has a considerable amount of reduction in distortion of 1.526 mm compared to that of other sequences. Welding sequence no. 4 is then followed by actual windmill tower fabrication, which resulted in reduced distortion level of 5 mm.

The contribution of impurities to unexpected cold cracks in a thick C-Mn steel plate

The internal cracking observed in a 6″-thick carbon-manganese steel plate after welding is discussed with respect to the presence of material impurities. The morphology and location of the cracks detected during fabrication of a heavy structure are typical of hydrogen-induced cracking (HIC) usually associated to hard untempered martensite. However, typically martensitic microstructures would not be expected for low carbon low alloy steels joints when a suitable welding procedure specification is adopted, which includes preheating and high heat input. This paper illustrates the morphology of the original cracks, which are unrelated to hard microstructures, and presents the results of the welding experiments conducted in samples cut from segregated regions of the 6″-thick plate. Through hydrogenation of thin slices containing impure regions and autogenous gas tungsten arc welding bead, it was possible to reproduce the same cracking characteristics formed during submerged arc welding, indicating that HIC may also be associated to softer phases. Hydrogen entrapment at the weld fusion line can be related to high impurities level due to the expected lower melting points at grain boundaries, explaining the HIC phenomenon. The present paper proposes a model for hydrogen cracking of bainitic structures at the welding heat affected zone that typically is not susceptible to crack.

MAG welding of 960QL quenched and tempered steel

The article presents research of the welding technology of S960QL quenched and tempered steel with the thickness of 10 mm. The main problem during welding heat-treated fine-grained steels is cold cracking. The aim of the research was to develop welding technology of tested steel to obtain high ductility and strength properties of the joint and to avoid the problem of crack formation after welding process. For the test the butt joint was welded. For this it was used MAG process in the flat position. Welding process was carried out based on preliminary tests and pre-prepared Welding Procedure Specification according to ISO 15609-1 standard. During welding the M21 mixture was used as the shielding gas. As the filler metal a solid wire G Mn4Ni2.5CrMo was used. The welded joint was tested in accordance with the ISO 15614 standard requirements. The research included non-destructive tests and destructive tests. The non-destructive tests included visual, magnetic particle and radiographic tests. The destructive tests included transverse tensile, root and face bend, impact, macroscopic, microscopic and hardness. Impact test was carried out in the temperature of - 20°C. Hardness measurements were made using the Vickers method and the load of 9.80 N. All of the tests ended with the positive result. The results of research show that tested welding technology and pre-heating temperature equal to 80°C allow to obtain a welded joint meeting the high quality requirements and the international standards requirements.

COMPUTATIONAL ANALYSIS TO CONTROL WELDING DEFORMATION IN THIN PLATE

Globally in the shipbuilding industry, the computational method is a more productive method than the experimental and machine learning method. The Thermal Elastic Plastic (TEP) method for computational analysis is simulated in the FEMAP Software to analyse the welding deformation of thin plates. To validate the non – linear behaviour of the thin plate, the computational and experimental results are compared. The TEP – FEM method assesses the welding deformation in the thin plate and optimizes the welding procedure specification and sequence to increase productivity.

Effect of SMAW parameters on microstructure and mechanical properties of AISI 1018 low carbon steel joints: An experimental approach

Welding technologies are the fundamental application in industrial field especially for engineering, manufacturing and even medical implants. Since welding process involved in form of heat energy, it creates a property change in welded location, thus adequate control of welding parameters is essential as it determined the characteristics of welded joint. In present work, the investigation on effect of SMAW process parameters on metallographic studies and mechanical properties of AISI 1018 low carbon joints is studied throughout series of well controlled welding parameters. Steel plates with dimension of 400mm*200mm*6mm are arc welded through different set of welding currents (55A to 90A) using SMAW machine with low hydrogen stick electrode. After completion of welding process, the characteristic of welded samples were evaluated by the mean of non-destructive (NT) and destructive test (DT) in accordance to standard specifications and requirements as specified in ASTM standard and AWS D1.1 respectively. DT such as tensile, bend, impact, micro-hardness and metallographic analysis subjected to effect of thermal arc energy are interpreted and compared. Lastly, an approved welding procedure specification (WPS) supported by laboratory test results is developed.

Effects of High Frequency Mechanical Impact on Fatigue Life of Semi-Automated Gas Metal Arc Welding (GTAW) of HSLA Butt Weld

This paper deals with a comprehensive investigation of fatigue life enhancement on semiautomated Gas Metal Arc Welding (GTAW) butt weld joint which is found almost everywhere in Malaysia welding structure steel sectors. The selected material in this study was high strength low alloy steel S460G2+M commonly used extremely in steel structure due to its outstanding mechanical properties. In this investigation, the method for joining the butt weld was conducted by unprofessional welder using semi-automated GMAW. At first, suitable welding parameters were identified and formulated into welding procedure specification (WPS) qualification conforming to AWS D1.1 standard. The test specimens were prepared and tested to ensure the welding quality. Further, the HFMI using Pneumatic Impact Treatment (PIT) technique were applied at the weld toe of the butt weld as tool for fatigue life enhancement. To investigate the influence of HFMI/PIT on the fatigue strength, the specimens were undergone fatigue test using universal fatigue machine using a constant amplitude loading. Finally, the comparison of the fatigue strength of as welded and treated specimens to indicate the beneficial influence of the treatment. Yes, the conduction by unprofessional welder using semi-automatic GMAW, the findings showed the improvement of fatigue strength and slope of S-N curves. In addition, the fracture location of test specimen shows physically affected by shifting from critical weld transition to base metal. The tensile test and hardness value also showed a slight difference as compared to untreated specimens.

Digitalized automated welding systems for weld quality predictions and reliability

The prevailing industrial and societal environment is driving welding manufacturing industries to employ green welding technologies for efficient, effective and reliable manufacturing and production. This paper presents current research work, whose aim is to develop a prototype of a commercial adaptive intelligent welding system with integrated weld quality attribute prediction and control. Supported by the study of scientific literature, initial results of experimental work which employed infrared thermography (IRT) based device and artificial intelligence (AI) system are discussed as a case study. Based on tested and validated welding samples, it is shown that the adaptive intelligent welding system being developed has self-monitoring capabilities for prediction of weld attributes, especially the depth of weld penetration, and has self-adjusting functionalities for weld control in off-line supervised conditions, and also can produce weldments of quality which conforms to EN ISO 5817. The findings imply that evolving welding technologies have practical industrial significance for monitoring and assurance, particularly as regards weld quality prediction and control, and, furthermore, as a tool to support decision-making when developing welding procedure specifications (WPS).

Fatigue Life Enhancement of Transverse and Longitudinal T-Joint on Offshore Steel Structure HSLAS460G2+M using Semi-automated GMAW and HFMI/PIT

This research deals with a method and procedure for enhancing the structural life of the commonly used steel structure in oil and gas industries HSLA S460G2+M with a thickness of 10 mm. The type of joint and welding process is T-joint with transverse and longitudinal attachment welded using semi-automated GMAW. Filler wire ER80S-Ni1 and mixed shielding gas (80% Ar / 20% CO2) is used as material consumables. At first, the best suitable welding parameters are comprehensively investigated, prepared, tested and qualified according to welding procedure specification (WPS) qualification requirements. Further, the weld toe is treated by using HFMI/PIT with a frequency of 90Hz, 2 mm pin radius and air pressure of 6 bars. In accordance with the recommendation of the International Welding Institute (IIW), fatigue test is conducted using constant amplitude loading with the stress ratio of 0.1 and loading stresses from 55% to 75% of the yield strength of the material. Finally, the results of the fatigue experimental are compared with the fatigue recommendation of as-welded and HFMI/PIT of IIW as well as the untreated raw material. As a conclusion, it is observed that the fatigue life is increased up to 300% compared to IIW and 70% to as-welded. It is also obvious that treated transverse T-joint shows significant improvement than the longitudinal attachment.

Investigation on HSLA Steel Weld Metal; Heterogeneous Microstructures and Mechanical Properties: Propose to Modify Welding Procedure Specification

Investigation on HSLA Steel Weld Metal; Heterogeneous Microstructures and Mechanical Properties: Propose to Modify Welding Procedure Specification

Additive Manufacturing by MMA Welding Process Characteristics and Microstructural, Mechanical Properties: Propose to Modify the Welding Procedure Specification

Additive Manufacturing by MMA Welding Process Characteristics and Microstructural, Mechanical Properties: Propose to Modify the Welding Procedure Specification

Variation in welding procedure specification approach and its effect on productivity

The research described was investigating the variation in Preliminary Welding Procedure Specifications (pWPSs) created at five weld shops. The purpose was to investigate the variation in chosen parameter values at each site as well as to identify any differences in weld result when welding according to the pWPSs. The study showed a vast variation between the sites, both in the chosen parameters and weld result. In order to use a Welding Procedure Specification (WPS) as a tool to facilitate standardization the variation in measurement systems, tolerance setting and starting points needs to be considered.

Influence of post weld heat treatment for weld joint of P355GH

From steel designed to work under pressure and exposed to high temperature apart from the good weldability, good mechanical properties are required. The guidelines set by the regulations require post welding heat treatment above 35mm thick. An important factor affecting the microstructure and properties of the joint made of thick-walled elements is heat treatment after welding. All welding operations must be properly planned before performing welding work. Welding procedure specification (WPS) is a document describing these operations, it is essential for proper determining of basics in planning welding operations and quality control in welding. The purpose of this paper is to compare the properties of joints made by 121 welding method in combination with and without post welding heat treatment.

Failures of Engineering Structures Caused by Weld Imperfections

The problematic of welding in terms of weld quality in dependence on service life of mechanical structures is discussed. Some examples of inadequate quality weld joints causing failure under load are described. Materials of the evaluated welds were following: S355 steel and Inconel 635 super alloy. Service conditions of homogeneous welds were different for both materials and weld quality was covered by Welding Procedure Specification. Using metallographic evaluation, the main problems were detected in a form of geometrical imperfections or insufficient penetration. These existing imperfections combined with static and dynamic load initiate the partial malfunction or failure of parts or constructions.

The European ITER Test Blanket Modules: EUROFER97 material and TBM’s fabrication technologies development and qualification

The paper overviews activities focused on qualification of EUROFER97 structural material, introduced under a probationary phase in the nuclear components design and construction code RCC-MRx, and identification/analyses of gaps in the respective material database to be filled in. Additionally the available design rules in the code are reviewed to verify their applicability to the specificities of EUROFER97 steel and to the TBM design and fabrication. Progress achieved in development of fabrication technologies and procedures applied for manufacturing of the TBM sub-components, like, HCLL and HCPB cooling plates, stiffening plates, first wall and side caps, and for TBM structure sub-assembly is described. The used technologies are based on fusion (laser and TIG) and diffusion (HIP) welding techniques taking into account specificities of the EUROFER97 steel. With help of the agreed notified body, an appropriate approach/methodology for qualification of the developed, TBMs-related preliminary welding procedure specifications has been identified and future steps established.

Toughness evaluation of EB welds

For over a hundred years, Charpy impact testing has been performed. It is one of the most frequently used material tests. Due to a very simple test setup, a huge wealth of experience and an enormous database of results, it is still state of the art to evaluate toughness of materials and welds. Modern welding technologies like laser welding or electron beam welding (EBW) are characterized by a low heat input. The high energy density of these technologies results in very narrow welds. These kind of joints are difficult to analyse by means of a standard Charpy test. The combination of weld cross section and properties lead in most cases to a fracture path deviation (FPD). Although the crack starts from a notch, it deviates during propagation into the heat-affected zone or even in the base material. Therefore, the weld itself is not tested and cannot be characterized. FPD is a well-known issue but so far little attention in standards has been paid to this complex topic. Hence, establishing a valid welding procedure specification for beam welding procedures may imply difficulties. This work focuses on avoiding FPD in electron beam welds in soft-matensitic steel (1.4313) by using standard and side notched Charpy impact specimens. Valid toughness result had to be found for 20- and 100-mm-thick welds at −20 ∘C. Several test with three different kind of specimen in two different heat-treated conditions were carried out. It was found that beside the narrow seam a major reason for FPD is the significant overmatching of the weld. A post weld heat treatment to reduce overmatching facilitates testing but can decrease toughness. Adequate results for qualification were found and EB welds reached sufficient toughness at −20 ∘C. Toughness of EB welds was compared to the toughness of conventional gas metal arc welds (GMAW). Finally, a recommendation for adapting the toughness characterization for narrow and overmatching seams is proposed.

Mechanical Behaviour of Welded Joints Achieved by Multi-Wire Submerged Arc Welding

The paper addresses the development of advanced welding technologies with two and three solid wires for joining of HSLA API-5l X70 (High-strength low-alloy) steel plates with thickness of 19.1 mm. The experiments were performed using a multi-wire Submerged Arc Welding (SAW) system that was developed for welding of steels with solid, tubular and cold wires, in different combinations. The main goal of the research was to assess the mechanical performances of the welded joints achieved by multi-wire SAW technology and then to compare them with the single wire variant, as reference system. The welded samples were firstly subjected to NDT control by examinations with liquid penetrant, magnetic particle, ultrasonic and gamma radiation, with the aim of detecting the specimens with flaws and afterwards to reconsider and redesign the corresponding Welding Procedure Specifications (WPS). The defect-free welded samples were subjected to tensile, Charpy V-notch impact and bending testing in order to analyse and report the mechanical behaviour of API-5l X70 steel during multi-wire SAW process. The experimental results were processed and comparatively discussed. The challenge of the investigation was to find the appropriate welding technology which responds simultaneously to the criteria of quality and productivity. Further research on metallurgical behaviour of the base material will be developed, in order to conclude the complete image of the SAW process effects and to understand how the multi-wire technologies affect the mechanical and metallurgical characteristics of the API-5L X70 steel used in pipelines fabrication.

Materials participation in welded joints manufacturing

Management of materials dilution to form a joint with higher features asked by complex metallic structures is a problem that took attention and efforts of welding processes researchers and this communication will give a little contribution presenting some scientific and experimental results of dilution processes studied by Welding Research Group from Iasi, Romania, TCM Department. Liquid state welding processes have a strong dependence related to dilution of base and filler materials, the most important are for automatic joining using welding. The paper presents a review of some scientific works already published and their contributions, results of dilution coefficient evaluation using weighing, graphics and software applied for shielded metal arc welding process. Paper results could be used for welders’ qualification, welding procedure specification and other welding processes researchers’ activities. The results of Welding Research Group from Iasi, Romania, TCM Department, show dilution coefficient values between 20-30 % of base material and 70-80 % of filler material for studied welding process.

Choice of welding consumable and procedure qualification for welding of 304HCu austenitic stainless steel boiler tubes for Indian Advanced Ultra Super Critical power plant

India has embarked on a mission programme for setting-up a coal-fired 800 MWe Advanced Ultra Super Critical (AUSC) power plant with steam parameters of 710/720 °C temperature and 30,400 kPa pressure. To implement this programme, India-specific version of 304HCu austenitic stainless steel (SS) and nickel-base Alloy 617M boiler tubes has been developed in collaboration with Indian manufacturers. The objective of the present study is to choose the appropriate gas tungsten arc (GTA) welding consumable for welding of 304HCu SS/304HCu SS and 304HCu SS/Alloy 617M dissimilar weld joints. Welding procedure specification (WPS) was prepared by using three types of filler wires, viz. ER304HCu, ERNiCrMo-3 and ERNiCrCoMo-1, for the 304HCu SS tube weld joints and ERNiCrCoMo-1 for the 304HCu SS/Alloy 617M dissimilar tube weld joints. Welding procedure qualification (WPQ) was carried out as per ASME Sec. IX requirements. Tube weld joints were also fabricated for evaluation of mechanical properties and for microstructural characterisation. Based on the detailed evaluation of mechanical properties, including creep, ER304HCu has been chosen for the similar welding of 304HCu SS and ERNiCrCoMo-1 for the dissimilar metal welding between 304HCu SS and Alloy 617M.