Welding and Joining Research Papers (original) (raw)

- by Girish Padhy
- •
- Welding and Joining

Heat Affected Zone (HAZ) simulation by Gleeble is a useful method for evaluating welding process parameters to improve the toughness of weld HAZ by optimizing process parameters. The HAZ Toughness in low alloy steels is strongly influenced by the welding parameters (as HAZ microstructure is influenced by the heat input and cooling rate). In the present work different regions of weld HAZ of API 5L X52 steel have been simulated by using Gleeble @ 3800 Thermal-Mechanical Simulator. Two cooling rates (t) 10 s to simulate low heat input 8/5 (LHI) welding conditions without preheating, (t) 40s to simulate high heat input (HHI) welding were used. 8/5 Charpy V-notch impact tests were conducted on the simulated as well as on the base material at room temperature (25º C) and at-40º C. Results showed that HHI simulated coarse grain HAZ (CGHAZ) region attributed highest Impact energy of 300 J in comparison to 199 J of base material at 25º C. In HAZ regions, lowest room temperature toughness was observed in sub critical HAZ (SCHAZ) for both HHI and LHI conditions. Lowest impact energy at-40º C was observed in fine grained HAZ (FGHAZ) for both HHI and LHI conditions. Hardness test showed that LHI samples exhibited slightly higher hardness than HHI condition and the hardness profile for HAZ regions was similar for both HHI and LHI conditions.

- by Samir Rabia
- •
- Welding Technology, Welding Engineering, Welding and Joining, Welding

The porosity formation in cold metal transfer (CMT) gas metal arc welding (GMAW) of zinc coated steel is studied over a wide range of the heat inputs (160–250 J /mm), which shows low porosity in weld bead (2% of bead area) in low (250 J /mm) and high (350 J/mm) heat inputs and maximum at medium (250–350 J/mm) heat inputs. The high speed imaging of weld pool shows that the highest frequency of zinc vapour escapes at high heat inputs compared to other conditions. Numerous experiments show that size and location of pores along with escaping of zinc vapour are the results of competition of viscosity of weld pool against buoyancy and vapour pressure within the time required to reach solidification temperature. Based on this concept, mechanisms involved in porosity formation, growth and escape phenomena are disclosed, which can help select the optimised welding conditions to obtain porosity free welds in CMT-GMAW of zinc coated steels.

- by Rumman Ul Ahsan
- •
- Welding and Joining, Arc physics

The present study elaborately discussed the effect of different modes of metal transfer (i.e., short circuit mode, spray mode and pulse mode) on grain structure and direction of grain growth in low nickel austenitic stainless steel weld metals. Electron backscattered diffraction (EBSD) analysis was used to study the grain growth direction and grain structure in weld metals. The changes in grain structure and grain growth direction were found to be essentially varied with the weld pool shape and acting forces induced by modes of metal transfer at a constant welding speed. Short circuit mode of metal transfer owing to higher Marangoni force (Ma) and low electromagnetic force (Rm) promotes the lowerweld pool volume(Γ) and higherweld pool maximumradius (rm). Short circuit mode also shows curved and tapered columnar grain structures and the grain growth preferentially occurred in <001> direction. In contrast, spray mode of metal transfer increases the Γ and reduces the rm values due to very high Rm and typically reveals straight and broad columnar grain structures with preferential growth direction in <111>. In the pulse mode of metal transfer relatively high Ma and Rm simultaneously increase the weld pool width and the primary penetration which might encourage relatively complex grain growth directions in theweld pool and cause a shift of major intensity from <001> to <111> direction. It can also be concluded that the fusion zone grain structure and direction of grain growth are solely dependent on modes of metal transfer and remain constant for a particular mode of metal transfer irrespective of filler wire used.

- by Dr. Manidipto Mukherjee and +1
- •
- Mechanical Engineering, Phase Transformations, Microstructure, Metallurgy
- by Danny Ferdiansyah
- •
- Piping, Welding and Joining, Piping Designing

Welding is the most important joining technology, which is well expressed by the appearance of a very large number of process-variations corresponding developed filler and auxiliary materials, and in a wide range of corresponding automation.
These are a combination of a welding base upon which the designer, technologist and manager can also build. To make this "construction" well substantiated, the present book intends to contribute by a systematic and concise overview of the units listed. The aim is a theoretical and practical summary which may support and
expand the background knowledge of those in contact with welding. It wishes to provide information in a compact and encyclopedic form to the readers of the welding part-area – the welding and allied processes, respectively the possibilities of mechanization – which simply be described as a technical background.
From a substantive point of view this book regards as allied technologies of welding the following:
- brazing and other joining technologies, such as the bonding and mechanical bonding;
- preparation of the workpiece (eg. cutting, chamfering) by thermal and other (erosion, shearing, chipping) form of cutting as a forming technology;
- and often the after bandage surface treatment, as a technology modifying the structure of matter, and thus adjusting quality.
This book presents the standardized marking systems and classification of welding and allied processes. This is the internationally accepted numerical sort of “common language" that all professionals understand independently of their ethnic background, and it represents the solid-script of reference in various fields.
Due to their characteristics of application, flexibly programmable industrial robots cooperating with peripheries are distinguished within the mechanization toolbar.
Their use increases productivity, reduces the cycle time of manufacturing, improves quality and reproduction, increases the flexibility of the production system, makes it possible to reduce monotonous and heavy physical work and substitutes human activity in areas harmful to health. The mechanization of welding conditions is usually determined by application of device-parts, as well as simple and complex devices, and auxiliary plants. These may also reduce welders physical wear and the welding side-time. The book also deals with these sub-divisions of welding.
A hegesztés a legfontosabb kötőtechnológia, amit jól kifejez az igen nagy számú eljárásváltozat megjelenése, a hozzájuk kifejlesztett hozag- és segédanyagok széles köre, a gépesítésük többféle lehetősége. Ezek együttese olyan hegesztés-technikai bázist jelent, amelyre egyaránt építhet konstruktőr, technológus és menedzser. Hogy ez az „építkezés” megalapozott lehessen, ahhoz a jelen könyv is hozzá kíván járulni a felsorolt témaegységek rendszerező, tömör szemléletű áttekintésével. Célja olyan elméleti és gyakorlati ismeretek összefoglalása, amelyek alátámaszt(hat)ják, illetve bővít(het)ik a hegesztéssel kapcsolatba kerülők háttérismereteit. Kompakt formában, enciklopédikusan igyekszik információkat nyújtani olvasóinak a hegesztés azon részterületeiről – a hegesztési és rokon eljárásokról, illetve a gépesítés lehetőségeiről – amelyeket egyszerűen technikai háttérnek is nevezhetünk.

Although procedures of fusion and press welding may be classified according to various aspects, the most typical one may be the energy source. According with this, different groups of welding procedures are to be distinguished on the basis of the use of electric arch or resistance heat, thermochemical reaction heat, mechanical (deformation and/or friction) energy as well as particle or electromagnetic radiation energy. The international standard classification of fusion and press welding procedures is correlated with the principle above. The first digit of the identity code of particular procedures and their variants (in case of the most widespread and important procedures) indicates the source of energy applied, the second refers to the technical endowment (the infrastructural arrangement), whereas the third serves to further differentiation between similar variants. Considering as criteria the source of the used energy, the most widespread fusion welding procedure is the arch welding, as well as the most significant press welding procedure is that using electrical resistance, The significance of the type of energy source is also indicated by the first digit of the code as follows: 1 for arch welding procedures and 2 for resistance welding procedures. Both goups of welding procedures are based on electrical phenomemons (more exactly, appartening to electricity, electrotechnics and electronics) and are realized as effect of heat produced by electricity. The basic infrastructural condition for all welding procedures is considered the welding equipment. As follows, cognition of the principle of functionning, of the build up and actioning of these equipments is essential. In order to perform the best exploitation of the performances of the welding equipment the technologist must have a continuous interest on the technical characteristics, the limits of parameters, the control of the system and the effects of this focusing on the work environment. Welding process parameters measurements and control solutions will be permanently taken in consideration. Focusing primarily on arch and resistance welding, the present book describes the theoretical and practical background, the technical characteristics and the related measurement, followed by the aspects of control and labour safety. It attempts to provide a survey of the particular fields of welding procedures mentioned above, which may support or expand the background knowledge of everyone interested in welding. It’s purpose consists in supplying the Reader information at a glance on some essential areas of welding like applications and measurement, control, and labour safety aspects).
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Az elektromos hegesztőberendezések alapfeltételét képezik a hozzájuk kapcsolódó hegesztési eljárásoknak, ezért fontossá válik alapelvük, felépítésük, működésük ismerete. Továbbá ahhoz, hogy hatékonyan kihasználhatók legyenek a bennük rejlő lehetőségek, célszerű foglalkozni alkalmazástechnikai jellemzőikkel: beállítási, illetve beavatkozási lehetőségeikkel, határértékeikkel, munkakörnyezeti hatásaikkal. Ennek szellemében a kapcsolódó mérésekre, irányítástechnikai megoldásokra is figyelmet kell szentelni. Természetesen nem szabad megfeledkezni az elektromosság veszélyeiről és azok elhárításáról sem. Ez a könyv elsősorban az ív- és az ellenállás-hegesztésre koncentrálva foglalkozik az alkalmazható berendezések, eszközök elvi és gyakorlati hátterével, üzemeltetési sajátosságaival, a kapcsolódó mérés-, irányítás- és biztonságtechnikai szempontokkal. Természetesen csak a teljesség igénye nélkül vállalkozik (vállalkozhat) a hegesztéstechnika felsorolt részterületeinek áttekintésére, amelyek alátámaszt(hat)ják, illetve bővít(het)ik a hegesztéssel kapcsolatba kerülők háttérismereteit. Viszonylag tömör, lényegre törekvő formában igyekszik információkat nyújtani Olvasóinak a hegesztés azon részterületeiről – a hegesztőberendezésekről, illetve azok mérés-, irányítás- és biztonságtechnikai vetületeiről –, amelyeket egyszerűen a hegesztéstechnikai háttérhez sorolhatunk.

In this study, a study on welding aluminum weldings with techniques such as TIG welding, MIG welding, Friction Stir welding, Laser Beam welding is compiled. Problems such as porosity, weld seam cracks and unstable arc that may occur as a result of the mentioned welding techniques have been investigated. The main purpose of this study is to examine the weldability of aluminum alloys and the causes and solutions of damage during or after welding. Apart from this purpose, information about the welding of aluminum alloys with other materials can be obtained. The effects of welding parameters on obtaining smooth welding products are mentioned. At the same time, the effect of the internal structure and chemical components of the alloys used on the welding process is not ignored.

- by Ahmet Enes Önder
- •
- Welding and Joining, Laser Welding, Aluminum, Aluminium Alloys

Various navigation systems are available to aid pedicle screw placement. The O-arm replaces the need for fluoroscopy and generates a 3-dimensional volumetric dataset that can be viewed as transverse, coronal, and sagittal images of the spine, similar to computed tomography (CT) scanning. The dataset can be downloaded to the Stealth system (Medtronic Navigation, Louisville, Colorado) for real-time intraoperative navigation.The main objectives of the current study were to assess (1) accuracy of pedicle screw placement using the O-arm/Stealth system, and (2) time for draping, positioning of the O-arm, and screw placement. Of 188 screws (25 patients), 116 had adequate images for analysis. The average time for O-arm draping was 3.5 minutes. Initial O-arm positioning was 6.1 minutes, and final positioning was 4.9 minutes. Mean time for screw placement, including O-arm draping and positioning and array attachment, was 8.1 minutes per screw. Mean time for screw placement alone was 5.9 minutes per screw. Screw placements on final O-arm images were on average 3.14 mm deeper than on the snapshot navigation images. Three screws (2.6%) breached the medial cortex, and 3 screws (2.6%) were misaligned and did not follow the pilot hole trajectory.The use of the O-arm/Stealth system was associated with a low rate of pedicle screw misalignment. The time to place screws was less than previously reported with CT navigation, but longer than conventional techniques. It is important to be aware of the potential discrepancy between snapshot navigation images and actual screw placement on final O-arm images. Our findings suggest that final screw positions may be deeper than awl positions appear on navigation images.

- by suresh patil
- •
- Welding and Joining
- by Aong J
- •
- Welding and Joining, Welding, Welding Metallurgy, WELDING METALLURGY SECOND EDITION

In magnetic pulse welding, electromagnetic pressure is used to deform, accelerate and weld workpieces. The process is mostly used for tubular specimens. In this article, the working principles of the process are described, and some... more

In magnetic pulse welding, electromagnetic pressure is used to deform, accelerate and weld workpieces. The process is mostly used for tubular specimens.
In this article, the working principles of the process are described, and some application examples are shown.

- by Koen Faes
- •
- Welding Technology, Welding Engineering, Welding and Joining, Welding

The metal 3-D printing market is currently dominated by high-end applications, which make it inaccessible for small and medium enterprises, fab labs, and individual makers who are interested in the ability to prototype and additively manufacture final products in metal. Recent progress led to low-cost open-source metal 3-D printers using a gas metal arc welding (GMAW)-based print head. This reduced the cost of metal 3-D printers into the range of desktop prosumer polymer 3-D printers. Consequent research established good material properties of metal 3-D printed parts with readily-available weld filler wire, reusable substrates, thermal and stress properties, toolpath planning, bead-width control, mechanical properties, and support for overhangs. These previous works showed that GMAW-based metal 3-D printing has a good adhesion between layers and is not porous inside the printed parts, but they did not proceed far enough to demonstrate applications. In this study, the utility of the GMAW approach to 3-D printing is investigated using a low-cost open-source metal 3-D printer and a converted Computer Numerical Control router machine to make useful parts over a range of applications including: fixing an existing part by adding a 3-D metal feature, creating a product using the substrate as part of the component, 3-D printing in high resolution of useful objects, near net objects, and making an integrated product using a combination of steel and polymer 3-D printing. The results show that GMAW-based 3-D printing is capable of distributed manufacturing of useful products for a wide variety of applications for sustainable development.

- by Joshua Pearce and +1
- •
- Engineering, Materials Science, Design, Digital Fabrication

This is an extract from the article:
Constantin Ciobanu, Levente Nogy: Rail thermal force calculations for jointed track. The Journal, Vol 135 Part 2, April 2017. Permanent Way Institution.
It presents the calculation of the joint resistance force for British rail joints, based on the bolt tightening torque and on the rail joint dimensional parameters.
It is extensively based on the calculation method presented by Prof Dr Eng Constantin Radu in the Railway Track Courses at the Technical University of Civil Engineering Bucharest (TUCEB).

- by Constantin Ciobanu and +1
- •
- Railway Transport, Rail Transport and Infrastructure, Welding and Joining, Railway Engineering

Final year project report

- by ahmad amir
- •
- Welding Engineering, Welding and Joining, Welding, GMAW

— The effect of welding current on the structure, tensile properties and performance of mild steel weld joints was studied. Mild steel plate (AISI 1018), 4mm thick, was used as base metal for preparing butt weld joints using shielded metal arc welding (SMAW) process. Welding currents of 65A, 70A, 75A and 80A were applied using 2.5mm diameter welding electrodes (E6011 and E6013). The tensile properties of the butt weld joints were determined using a universal tensile testing machine model S/N 8889 in accordance with ASTM procedures. Macrostructural investigations showed good penetration in all the weld joints. Welding current of 75A produced maximum yield strength, ultimate tensile strength values of 358.50MPa, 421.70MPa respectively for weldments produced with E6011 while weldments produced with E6013 gave a maximum ultimate tensile strength and yield strength values of 383.20MPa and 319.37MPa respectively all of which were lower than those of the base metal. The percentage elongation of the base metal, (14.28%), was found to be lower than that of the weld joints produced.

- by Ogbunaoffor Chukwuemeka
- •
- Welding and Joining
- by Dr. Manidipto Mukherjee
- •
- Welding Technology, Welding Engineering, Welding and Joining, Welding

P. Rombaut. Joining of dissimilar materials through rotary friction welding. Master thesis presented in fulfillment of the requirements for the degree of Master of Science in Engineering. Department of Mechanical Construction and Production, Faculty of Engineering, Ghent University, Academic year 2010-2011.
Promotor : prof. dr. ir. W. De Waele
Mentor : dr. ir. K. Faes

- by Koen Faes
- •
- Welding Technology, Welding Engineering, Welding and Joining, Friction Welding

Industri minyak dan gas (migas) merupakan salah satu bidang yang paling besar memberikan dana kontribusi dalam pembangunan suatu Negara. Migas juga merupakan salah satu sector industri vital di Indonesia. Industri migas memproduksi bahan bakar yang membantu untuk kegiatan sehari-hari masyarakat di Indonesia. Tanpa bahan bakar minyak masyarakat Indonesia saat ini akan kesulitan dalam menjalankan aktivitas mereka. Oleh karena itu industry migas di Indonesia memegang peranan pening dalam mendukung dan menjaga ketahanan energi nasional. PT Pertamina (persero) merupakan bahan usaha milik negara (BUMN) yang bergerak di bidang energy yaitu minyak dan gas. PT Pertamina (Persero) memeiliki 6 unit pengolahan (refinery) yang tersebar di berbagai daerah di Indonesia. PT Pertamina (Persero) Refenery Unit IV Cilacap merupakan refinery unit terbesar dari enam unit yang masih beroperasi. Sebagai unit pengolahan terbesar tentunya memiliki sarana dan prasarana yang memadai termasuk kilang dan pipa-pipa yang menyertainya. Sebagai salah satu divisi yang berada di PT Pertamina Refenery Unit IV Cilacap maka stationary and inspection engineering memiliki fungsi untuk melakukan inspeksi terhadap kualitas dari peralatan yang akan dipakai dan melakukan maintenance planning terhadap umur pakai semua perlatan yang ada di lapangan. Welding inspection merupakan salah satu inspeksi yang dilakukan untuk mengetahui hasil dari proses pengelasan yang dilakukan. Hasil dari proses welding merupakan salah satu unsur yang cukup penting dalam berjalannya proses produksi di PT Pertamina karena menentukan umur pakai dari sebuah alat. Hasil dari maintenance yang dilakukan pun menentukan apakah alat tersebut bisa digunakan kembali atau tidak. Welding proses yang biasa dilakukan biasanya diakibatkan dari korosi yang menyebabkan cacat pada alat yang digunakan sehingga alat tersebut tidak berjalan normal. Pada proses pemeriksaan pengelasan, kualitas las

- by Samir Rabia
- •
- Welding Technology, Welding Engineering, Welding and Joining, Welding

MIG, the welding process which can be applied for many kind of materials, was used on 6XXX series of aluminum to perform a joining to be able to investigate hardships and trials of MIG welding on aluminum type of metal when it’s used instead of TIG process for nonspecific applications. Because when it’s preferred instead of TIG, one of the major issues with MIG process for aluminum is implementation part( Handicraft requirements etc). No attention on purpose paid to surface cleaning. Different welding techniques have been used on this case and the sample has been examined by optical microscope, SEM, EDX and hardness test. As the results of the tests, first of all, it was shown that MIG is trickier method than TIG throughout implementation of welding. Not to pay attention to surface cleaning caused dendritic structures which were located as small clusters on the surface due to the NaCl droplets which were identified by EDX chemical composition analysis. Also, SEM analysis rendered possible to determine dendritic structures, inclusions which we couldn't have determined without SEM, and there was a chance to examine hardness of a metal part which had been produced by mechanical extrusion method. Different hardness values were obtained on the parent material because of extrusion. In the fusion zone of the material, as expected there was decrease of hardness because of incidents which occurred during heating and cooling cycles.

- by Mert Karakaplan
- •
- Welding Technology, Welding Engineering, Welding and Joining, Friction Welding

Proses pembangunan kapal merupakan suatu aktivitas yang dilakukan mulai dari perencanaan kapal (desain) sampai dengan penyerahan produk kapal kepada pemilik kapal. Pembangunan kapal ini dilakukan melalui suatu tahapan proses yang salah satunya yaitu pembentukan blok – blok badan kapal yang dilakukan di building berth. Kemudian blok-blok tersebut disatukan menjadi blok yang lebih besar di assembly area. Aktivitas penyambungan blok-blok kapal tersebut tidak lepas dari aktivitas pengelasan. Proses pengelasan ini sangat penting dikarenakan untuk melakukan joint bagian-bagian hull kapal. Dimana dalam proses pengelasan (welding) tidak boleh ada kesalahan sekecil apapun baik berupa crack, over heat, dan sebagainya. Proses pengelasan ini merupakan bagian yang amat vital dalam proses pembangunan kapal.
Maka dari itu dalam proses pengelasan diperlukan hal-hal yang harus diperhatikan oleh para surveyor dan para welder. Dalam makalah ini akan dibahas mengenai beberapa hal yang berkaitan dengan welding.

- by Reva Permadi
- •
- Naval Engineering, Naval Architecture, Welding Technology, Welding Engineering

The engineering parts joining by the spot welding require acceptable properties to survive the loading conditions. Several studies show that the welding variables have an effect on the properties of spot nugget and on the future cracking. This review summarizes the resistance spot welding process (RSW). It introduces the basic spot welding principles, experiments, limitation and defects. The new concepts and awareness were presented. The results from the series of scientific works and literature are discussed. The metal’s weldability, strength, and fracture are the main topics in several structural analysis. The welding variables effect on the mechanical properties and performance of the structures is the key analysis. In general, the increasing of the heat input by adjusting the current, time, and pressure producing higher weld area in turn enhance the toughness. However, by increasing the weld area, the defects and cracking tend to appear. Hence, a desired weld size with the mechanical properties is required. The nugget fracture mode is changing from plug or button tearing to shear failure mode depending on the weld properties. The crack grows either from the internal defects or around the nugget.

- by A.M. Al-Mukhtar
- •
- Fracture, Welding Technology, Welding Engineering, Automotive Industry

This study has been aimed to find out the proper welding procedure/conditions for a newly developed Fe-16Cr-1Ni-9Mn-0.12N austenitic stainless steel (ASS), which is uniquely modified from 200 series alloy, in order to control the microstructural metastability of the weld metals. The welded joints of 4 mm thick sheet were prepared in a square butt configuration by using three modes of metal transfer, i.e., short-circuit (SC), spray (S), and pulse (P) mode of metal transfer and three austenitic filler metals (304L, 308L and 316L) under two shielding gas environments using gas metal arc welding (GMAW) process. It is observed that the variation in modes of metal transfer and filler metals can effectively manipulate the metastability of γ-phase, formation of δ-phase and grain size of the weld metals. Among the modes of metal transfer, pulse mode of metal transfer produces more me-tastable γ-phase and higher δ-phase fraction responsible for finer grain structure in weld metals irrespective of filler metals used. Again, higher microstructural metastability was obtained with the 304L filler metal irrespective of modes of metal transfer used. It is evident that the weld metals having higher microstructural me-tastability also improved mechanical properties (i.e. hardness, strength and toughness). However, weak fusion boundary (FB) region of welded joint limits the beneficial effect of metastability and creates a weakest link in the joint. On the other hand, high temperature heat affected zone (HTHAZ) having a coarse austenite grain surrounded by grain boundary precipitates is governed only by the modes of metal transfer.

A hegesztés az iparban a fémes anyagok legfontosabb kötési technológiája, amit jól kifejez az igen nagy számú eljárásváltozat megjelenése, a hozzájuk kifejlesztett hegesztőanyagok széles köre és a gépes, automatizálás sokféle lehetősége. Ez a kis könyvecske azt a célt szolgálja, hogy a hegesztés alapvető folyamatainak megismertetésével elősegítse a Fémek technológiája ismeretanyagának elsajátítását, és kedvet teremtsen az abban való alaposabb elmélyüléshez, anyagtechnológiai mérnökséghez, amely a gépészmérnöki szakmai pálya egyik legizgalmasabb szakiránya.

Friction Stir Welding (FSW) is considered to be the most significant development in metal joining in last two decades. FSW has many advantages when welding magnesium or lightweight alloys. The Friction stir welding of magnesium alloy has many potential applications in major industries i.e. land transportation, aerospace, railway, shipbuilding and marine, construction, and many other industrial applications. Even magnesium alloys have been used in industrial equipment of nuclear energy as magnesium alloys have low tendency to absorb neutrons, sufficient resistance to carbon dioxide and excellent thermal conductivity. Recently, the research and development in FSW field and associated technologies have been developing rapidly worldwide. In this review article, the basic principle of friction stir welding and several aspects of friction stir welded magnesium alloys have been described. The current state of friction stir welding of magnesium alloys is summarized. In spite of this, much remains to be learned about the process and opportunities for further research are identified.

- by Kulwant Singh and +1
- •
- Welding and Joining, Friction Stir Welding, Magnesium Alloys, Lightweight material

The present study describes in detail the effect of shielding gas mixtures on the bead geometry, microstructure, and mechanical properties of gas metal arc welded modified ferritic stainless steel (409M) sheets (as received) of 4 mm thickness. The welded joints were prepared under spray (S) mode of metal transfer at same heat input using 308L austenitic filler metal and four different shielding gas mixtures, i.e., pure Ar, Ar + 5% CO2, Ar + 10% CO2, and Ar + 20% CO2. The welded joints were evaluated by means of microstructural changes, hardness, tensile strength, and toughness. The dependence of weld metal microstructure on shielding gas mixtures has been determined by bead geometry, Creq/Nieq ratio, Ms, M􀀁s, optical microscopy (OM), transmission electron microscopy (TEM), and electron probe microanalyzer (EPMA). It was observed that the variation in shielding gas mixture effectively manipulates the solidstate phase transformation and precipitation behavior of the welded joints. Variations in microstructure ultimately affect the mechanical properties of the weld metal as well as coarse-grained HAZ (CGHAZ). The present study concluded that up to 10% CO2 may be commercially utilized in the shielding gas mixture for fabricating welded joints of 409M using 308L filler metal without deteriorating microstructural and mechanical properties.

- by Dr. Manidipto Mukherjee
- •
- Phase Transformations, Microscopy, Metallurgy, Welding Technology
- by Girish Padhy
- •
- Welding and Joining

Aluminum (Al) and copper (Cu) have been widely used in many industrial fields thanks to their good plasticity, high thermal conductivity and excellent electrical conductivity. An effective joining of dissimilar Al and Cu materials can make full use of the special characteristics of these two metals. Friction stir spot welding (FSSW), as an efficient solid-state welding method suitable for joining of dissimilar metal materials, has great prospects in future industrial applications. In this paper, the FSSW studies on Al-Cu dissimilar materials are reviewed. The research progress and current status of Al-Cu FSSW are reviewed with respect to tool features, macroscopic characteristics of welded joints, microstructures, defects in welds and mechanical properties of joints. In addition, some suggestions on further study are put forward in order to promote the development and progress of Al-Cu FSSW studies in several respects: material flow, thermal history, addition of intermediate layer, auxiliary methods and functionalization of Al-Cu FSSW joint.

- by Chaoqun Zhang
- •
- Welding Engineering, Intermetallics, Welding and Joining, Aluminum

Welding is an important joining technology but the defects in welds wreck the quality of the product evidently. Due to the variety of weld defects' characteristics, weld defect detection is a complex task in industry. In this paper, we try to explore a possible solution for weld defect detection and a novel image-based approach is proposed using small X-ray image data sets. An image-processing based data augmentation approach and a WGAN based data augmentation approach are applied to deal with imbalanced image sets. Then we train two deep convolutional neural networks (CNNs) on the augmented image sets using feature-extraction based transfer learning techniques. The two trained CNNs are combined to classify defects through a multi-model ensemble framework, aiming at lower false detection rate. Both of the experiments on augmented images and real world defect images achieve satisfying accuracy, which substantiates the possibility that the proposed approach is promising for weld defect detection.

- by Chaoqun Zhang
- •
- Image Processing, Welding Engineering, Welding and Joining, Deep Learning

Pipelines Welding Handbook

- by Samir Rabia
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- Welding Technology, Welding Engineering, Welding and Joining, Welding

The Germany has launched a new initiative for industries, which had led to the Industry 4.0 concept. This initiative has received very fast a global interest from all industrialized countries that have started already the 4th industrial revolution, following the German model. All important welding equipment manufacturers offers new modern solutions/applications that allow digitalization of all essential data, like welding parameters, that are now sent from the workplace to the facilities server, using wireless technology, the data being stored further in a cloud. These data can be accessed from any chain fabrication point, materials suppliers, quality control divisions, clients etc. improving the traceability process. In this entire general context, the materials weldability is playing a key role, because, based on that property it can be established productivity and quality process features, but also the reliability and safety of the welded structures in exploitation. Not in the last, it can be realized different studies and researches aiming the processes optimization, cost control, predicting the welded structures lifetime exploitation & performance.

- by Marius Bodea
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- Welding and Joining, Welding, Welding Metallurgy

In this study, a bead on plate welding on a low carbon steel plate at different parameter combinations in double-pulsed gas metal arc welding (DP-GMAW) process has been carried out. The effect of heat input, pulse frequency and thermal pulse frequency on solidification variables and microstructure of the weld metal have been thoroughly studied. Formation of inclusion and acicular ferrite during solidification has been calculated to observe the effect of process parameters on the microstructural constituents. Furthermore, the microhardness analysis of the weld metals has been carried out to evaluate the effect of microstructural variations on the property. Several linear and non-linear equations have also been developed to predict the responses as a function of different process variables. The results indicate that decrease in heat input, pulse frequency and thermal pulse frequency increases the volume fraction of inclusion and acicular ferrite in the weld metals. The higher volume fraction of acicular ferrite ultimately results in fine grain microstructure with the higher hardness of weld metals. On the other hand, the grain size of coarse grain heat affected zone (CGHAZ) at lower heat input was finer which ultimately increases the heat affected zone hardness.

Keywords: 3-D printing, gas metal arc weld, GMAW, metal inert gas welding, MIG welding, additive manufacturing, metal printing Open-source hardware RepRap Welder Welding Metal 3-D printing, low cost metal 3-D printer, open-source metal 3-D printer, GMAW 3-D printing Wire Arc Additive Manufacturing WAAM a b s t r a c t Low-cost high-resolution metal 3-D printing remains elusive for the scientific community. Low-cost gas metal arc wire (GMAW)-based 3-D printing enables wire arc additive manufacturing (WAAM) for near net shape applications, but has limited resolution due to the complexities of the arcing process. To begin to monitor and thus control these complexities , the initial designs of the open source GMAW 3-D printer have evolved to include current and voltage monitoring. Building on this prior work, in this study, the design, fabrication and use of the open source arc analyzer is described. The arc analyzer is a multi-sensor monitoring system for quantifying the processing during WAAM, which includes voltage, current, sound, light intensity, radio frequency, and temperature data outputs. The open source arc analyzer is tested here on aluminum WAAM by varying wire feed rate and measuring the resultant changes in the sensor data. Visual inspection and microstructural analysis of the printed samples looking for the presence of porosity are used as the physical indicators of quality. The value of the sensors was assessed and the most impactful sensors were found to be the light and radio frequency sensors, which showed arc extinction events and a characteristic ''good weld" peak frequency.

- by Joshua Pearce and +1
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- Engineering, Sensors and Sensing, Manufacturing, Process Control

Le vicende della seconda guerra mondiale non sono state per la Regia Marina una sfilata di cigni neri che hanno imperversato sulla nostra sorte nel quadro di un confronto equilibrato con gli avversari
L’ inesistente cigno nero è stata la distanza tra la nostra impreparazione industriale e quella degli avversari, con il loro sviluppo tecnico e la loro disponibilità di nuove tecnologie, la loro capacità di produzioni di massa, con generazioni di eccellenti soldati e marinai vittime di una propaganda che parlava delle nostre supremazie e si compiaceva dei nostri traguardi senza guardare né lasciarci guardare al di là della soglia di casa.
Questo studio approfondisce il tema delle costruzioni saldate e chiodate a complemento di precedenti analisi citate in bibliografia ed è stato sviluppato non sulla base delle conoscenze attuali e delle maggiori possibilità di attingere praticamente a qualsiasi archivio, ma cercando di fornire un quadro di valutazione, una base storica per ulteriori studi, rispettando e rispecchiando le conoscenze e capacità nel campo delle costruzioni navali, di grandi navi veloci e di navi militari, che costituivano lo stato dell’arte della fine degli anni 30, in quell’ isola a cui si era ridotta l’Italia.
Si è cercato di rispecchiare le conoscenze, la preparazione, le informazioni e nel possibile i mezzi di cui disponevano i pianificatori ed i decisori italiani dell’epoca, condizioni che avrebbero potuto servire anche per evitare il disastro a cui andò incontro la Regia Marina Italiana.
La conclusione è che mancò la conoscenza, la consapevolezza, dei limiti dell’industria italiana del tempo e della relativa classe dirigente.
Il tema generale ‘ quello delle capacità della Regia Marina Italiana di affrontare la 2^ GM, ma porse più che di capacità bisognerebbe parlare di possibilità che non erano alla portata.

Friction stir welding (FSW) process is a solid state joining process in which a non-consumable tool is used to generate frictional heat in the abutting surfaces. The welding parameter such as welding speed, tool rotational speed, and tool profile plays a major role in deciding the weld joint strength. In this investigation, effect of welding parameters and tool pin profile on Mechanical properties in AA6061 aluminium alloy was studied. Friction stir welding of aluminium alloy plates with a thickness of 6 mm are used to perform Friction Stir Weld joints. Tapered cylindrical, and square pin profiles have been used to fabricate the joints at three different rotational speeds i.e. 1500, 2000 and 2500 rpm with two traverse speeds of 20 and 40 mm/min. The mechanical properties (tensile strength, hardness) of the joints have been evaluated and analysed. It has been observed that the design of tool pin profile has considerable effect on tensile properties. Square pin profile tool produces the best tensile properties compared to tapered cylindrical tool pin profiles.