DOCSLIB.ORG

Laser and Electron Beam Welding of Ti-Alloys: Literature Review

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Laser and Electron Beam Welding of Ti-Alloys: Literature Review y GKSS S 2MB RECEIVED APR 08698 O ST * Laser and Electron Beam Welding of Ti-Alloys: Literature Review mTEGH-^M Autoren: tA" G. Qam FORCE J. F. dos Santos THYSSEN LASER-TECHNIK GMBH INSTITUTE M. Kogak GKSS 97/E/35 DISCLAIMER Portions of this document may be illegible electronic image products. Images are produced from the best available original document. GKSS 97/E/35 Laser and Electron Beam Welding of Ti-Alloys: Literature Review Autoren: G. Gam J. F. dos Santos M. Kogak (Institut fur Werkstofforschung) GKSS-Forschungszentrum Geesthacht GmbH • Geesthacht • 1997 Die extemen Berichte der GKSS werden kostenlos abgegeben. The delivery of the external GKSS reports is free of charge. Anforderungen/Requests: GKSS-Forschungszentrum Geesthacht GmbH Bibliothek/Library Postfach 11 60 D-21494 Geesthacht AIs Manuskript vervielfaltigt. Fur diesen Bericht behalten wir uns alle Rechte vor. GKSS-Forschungszentrum Geesthacht GmbH • Telefon (04152)87-0 Max-Planck-StraBe • D-21502 Geesthacht / Postfach 11 60 • D-21494 Geesthacht GKSS 97/E/35 Laser and Electron Beam Welding of Ti-Alloys: Literature Review G. £am, J. F. dos Santos, M. Kogak 36pages with 2 figures and 7 tables Abstract The welding of titanium alloys must be conducted in completely inert or vacuum environments due to the strong affinity of titanium to oxygen. Residual stresses in titanium welds can greatly influence the performance of a fabricated aerospace component by degrading fatigue properties. Moreover, distortion can cause difficulties in the final assembly and operation of high-tolerance aerospace systems. Power beam welding processes, namely laser and electron beam welding, offer remarkable advantages over conventional fusion welding processes and have a great potential to produce full-penetration, single-pass autogenous welds with minimal component distortion due to low heat input and high reproducibility of joint quality. Moreover, electron beam welding process, which is conducted in a vacuum chamber, inherently provides better atmospheric protection. Although considerable progress has been made in welding of titanium alloys by power beam processes, there is still a lack of a complete set of mechanical properties data of these joints. Furthermore, the problem of solid-state cracking in fusion welding of y-TiAl intermetallic alloys due to their low ductility is still to be overcome. The purpose of this literature review is to outline the progress made in this area and to provide basic information for the Brite-Euram project entitled Assessment of Quality of Power Beam Weld Joints ”ASPOW“. Laser- und ElektronenstrahlschweiBen von Titan-Legierungen: Literaturrecherche Zusammenfassung Wegen der sehr starken Affinitat des Titans zum Sauerstoff muB das SchweiBen von Titanlegiemngen unter Schutzgas oderim Vakuum erfolgen. Eigenspannungen in TitanschweiBnahten kbnnen das Bauteilverhalten durch Degradation der Ermudungseigenschaften erheblich negativ beeinfluBen. Daruber hinaus kann die Formanderung Schwierigkeiten in der Endmontage und Handhabung von paBgenauen Komponenten, z.B. im Flugzeugbau, hervorrufen. Gegenuber den klassischen SchweiBverfahren hat die Laser- und Elektronen- strahlschweiBtechnik den Vorteil einer geringen Formanderung durch niedrigen Warmeeintrag und ermoglicht dadurch eine hohe B auteilreproduzierbarkeit. Des weiteren bieten ElektronenstrahlschweiBprozesse, die in V akuumkammem durchgefuhrt werden, einen optimalen Schutz gegen atmospharische Umgebungseinflusse. Obwohl Fortschritte in der SchweiBung von Titanlegiemngen mit Laser- oder Elektronenstrahlen erzielt wurden, fehlt bisher immer noch eine vollstandige mechanische Charakterisierung dieser SchweiBnahte. Weiterhin muB das Problem der Kaltrifineigung beim SchmelzschweiBverfahren von intermetallischen y-TiAl-Legierungen, welches auf die geringe Duktilitat zuriickzufuhren ist, gelost werden. Ziel dieser Literaturrecherche ist es, den Stand der Forschung und Entwicklung auf diesem Gebiet darzu- stellen und grundlegende Informationenfur das Brite-Euram-Proj ekt, Assessment of Quality of Power Beam Weld Joints (ASPOW) zu liefem. Manuscript received /Manuskripteingang in der Redaktion: 13. August 1997 Preface Present literature survey is conducted in the framework of the BRITE-EURAM Project (BRPR-CT95-0021); Assessment of Quality of Power Beam Welds - ASPOW This project includes laser and electron beam weldability as well as testing and evaluation aspects of most commonly used metallic materials and their welded joints. In order to provide comprehensive state-of-the-art information on the scope of the project, following reports concerning the weldability aspects have been prepared: • Laser and electron beam welding of Al-alloys: Literature Survey • Laser and electron beam welding of Ti-alloys: Literature Survey • Laser and electron beam welding of Superalloys: Literature Survey • Laser and electron beam welding of Stainless Steels: Literature Survey • Laser and electron beam welding of C-Mn Steels: Literature Survey Additionally, a state-of-the-art report on the testing and evaluation procedures of the laser and electron beam welded structures will also be prepared in due course. August 1996 Dr. Mustafa Kogak, GKSS Project Coordinator ASSESSMENT OF QUALITY OF POWER BEAM WELD JOINTS (ASPOW) Contr.Nr: BRPR-CT95-0021 Duration: 1.2.1996-31.1.1999 Total Budget: 3.372.600 ECU PARTNERS: GKSS RESEARCH CENTER - ERG (Project Coordinator) THYSSEN LASER TECHNIK - ERG CNIM - France RTM - Italy FORCE INSTITUTES - Denmark QU ANTED - France INTERTURBINE - FRG NU-TECH - FRG BRITISH STEEL - UK ANSALDO TERMOSUD - Italy PROTECT SUMMARY Despite significant improvements in power beam welding technology over recent years, it still remains impossible to characterise laser and EB welds in a unique fashion and to produce quantifiable mechanical properties. Guidance on design aspects of power beam welded joints is currently lacking for potential users so that they are often reluctant to opt for such a welding process despite the available technology to fabricate the joint. The objective of this industrial project is to provide an improved understanding of the failure behaviour of similar and dissimilar laser and EB welds in order to be able to predict structural performance. The proposed programme will extend current non-destructive (NDT) and destructive testing standards to power beam welded joints and will result in recommendations for best practice and the changes necessary to current techniques to achieve this. In order to accomplish this, it is necessary to: i) Identify major weldability and joint quality problems for various materials. ii) Develop techniques for the identification of defect types (NDT) and determination of mechanical and fracture behaviour of joints. iii) Develop and validate a methodology - European Quality Assessment Concept (EQAC)- for structural integrity assessment of power beam welded joints which takes into account the unique features of these joints iv) Provide a first Weld-Defect-Catalogue for power beam weld joints using improved NDT methodology (p-focus X-ray radiography and radioscopy). The European Quality Assessment Concept (EQAC) for power beam welds to be developed in this project will consider the unique features of power beam welds and their defects on various materials. Present mechanical and NDT standards do not take into account these features (strength mismatch, defect types and weld shape etc.) of power beam welds in a unified fashion. The structural reliability of these welds urgently needs a systematic effort to show their suitability for conventional as well as advanced structural components. Testing of structural components used in aerospace and civil engineering will be included to determine structural performance and validate the developed EQAC. This project covers laser and electron beam weldability aspects of over twenty metallic structural materials including various Al-alloys. It will also establish Nd:YAG laser welding conditions for optimum weld properties of Al-alloys by developing new super pulsed Nd:YAG laser for this purpose. The consortium comprises a Research Center (GKSS) specialized in testing and assessment of weld defects, a YAG laser manufacturer (QUANTEL), a manufacturer of laser welded steel components (Thyssen Laser Technik), a company specialized on EB-welding of large structural components (CNIM), a company user of both power beam welding processes in repair of aerospace components and end user of the NDT for the inspection of the same components (INTERTURBINE), a steel manufacturer and large scale testing laboratory (BRITISH STEEL), a company experienced in C02 laser welding of advanced materials (RTM), a company specialising in NDT (NU-TECH), a research center (FORCE) with experience on laser welding of steels, a company (ANSALDO) manufacturing medium-heavy industrial and power plant components. CONTENTS Page 1. Introduction 5 2. Strengthening Mechanisms of Titanium Alloys 10 3. Weldability Considerations 13 3.1. Weldability of Titanium Alloys 13 3.1.1. Alpha and Near-Alpha Alloys 13 3.1.2. Alpha-Beta Alloys 14 3.1.3. Intermetallic Alloys 15 3.2. Weld Microstructure 16 3.3. Weld Defects 17 3.4. Post-Weld Heat Treatment 18 3.5. Mechanical Properties of Welded Joints 19 3.5.1. Tensile Properties 19 3.5.2. Fracture Toughness 21 4. Final Remarks 22 5. References 23 ASPOW Literature Survey (BRPR-CT95-0021) 1. INTRODUCTION Titanium has a low density (4.5 g/cm 3 ), almost half of that of steel (7.83 g/cm 3 ) and high melting point (-1678 °Q which gives an indication
Load more

Recommended publications
  • Beam Welding
    EAA Aluminium Automotive Manual – Joining 4. Beam welding Contents: 4. Beam welding 4.0 Introduction 4.1 Laser beam welding 4.1.1 Laser sources 4.1.1.1 CO2 lasers 4.1.1.2 Solid state lasers 4.1.2 Laser beam welding processes 4.1.2.1 Heat conduction welding 4.1.2.2 Deep penetration welding 4.1.2.3 Twin laser welding 4.1.2.4 Remote laser welding 4.1.2.5 Laser welding of tubes, profiles and tailored blanks 4.1.2.6 Laser deposit welding 4.1.3 Laser welding defects 4.1.4 Joint configurations 4.1.5 Addition of filler wire 4.1.6 Shielding gases for laser welding 4.1.7 Characteristics of laser welding of aluminium alloys 4.2 Electron beam welding 4.2.1 Vacuum electron beam welding 4.2.2 Non-vacuum electron beam welding 4.2.3 Electron beam welding of aluminium alloys Version 2015 ©European Aluminium Association ([email protected]) 1 4.0 Introduction This chapter provides a technical overview of the unique features of the beam welding processes: - Laser Beam Welding (LBW) and - Electron Beam Welding (EBW) including several examples of automotive aluminium applications. Apart from welding, both process techniques are also used for cutting and for surface treatment of aluminium products. Electron beam welding results in very deep, narrow penetration at high welding speeds. It is usually carried out in a vacuum chamber, but also non-vacuum welding machines are used. The low overall heat input of electron beam welding enables to achieve the highest as-welded strength levels in aluminium alloys.
    [Show full text]
  • Introduction to Non-Arc Welding Processes
    Introduction to Non-Arc Welding Processes Module 2B Module 2 – Welding and Cutting Processes Introduction to Non-Arc Welding Processes Non-Arc Welding processes refer to a wide range of processes which produce a weld without the use of an electrical arc z High Energy Density Welding processes Main advantage – low heat input Main disadvantage – expensive equipment z Solid-State Welding processes Main advantage – good for dissimilar metal joints Main disadvantage – usually not ideal for high production z Resistance Welding processes Main advantage – fast welding times Main disadvantage – difficult to inspect 2-2 Module 2 – Welding and Cutting Processes Non-Arc Welding Introduction Introduction to Non-Arc Welding Processes Brazing and Soldering z Main advantage – minimal degradation to base metal properties z Main disadvantage – requirement for significant joint preparation Thermite Welding z Main advantage – extremely portable z Main disadvantage – significant set-up time Oxyfuel Gas Welding z Main advantage - portable, versatile, low cost equipment z Main disadvantage - very slow In general, most non-arc welding processes are conducive to original fabrication only, and not ideal choices for repair welding (with one exception being Thermite Welding) 2-3 High Energy Density (HED) Welding Module 2B.1 Module 2 – Welding and Cutting Processes High Energy Density Welding Types of HED Welding Electron Beam Welding z Process details z Equipment z Safety Laser Welding z Process details z Different types of lasers and equipment z Comparison
    [Show full text]
  • Characterisation of Intermetallic Phases in Fusion Welded Commercially Pure Titanium and Stainless Steel 304
    metals Article Characterisation of Intermetallic Phases in Fusion Welded Commercially Pure Titanium and Stainless Steel 304 Timotius Pasang 1,*, Stevin Snellius Pramana 2 , Michael Kracum 3, Wojciech Zbigniew Misiolek 3 , Mona Aziziderouei 1, Masami Mizutani 4 and Osamu Kamiya 5 1 School of Engineering, Computer and Mathematical Sciences, Auckland University of Technology, Auckland 1020, New Zealand; [email protected] 2 School of Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU, UK; [email protected] 3 Loewy Institute & Department of Materials Science and Engineering, Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015, USA; [email protected] (M.K.); [email protected] (W.Z.M.) 4 Joining and Welding Research Institute (JWRI), Osaka University, Osaka 567-0047, Japan; [email protected] 5 Faculty of Engineering Science, Department of System Design Engineering, Akita University, 1-1 Tegatagakuen-machi, Akita 010-8502, Japan; [email protected] * Correspondence: [email protected] Received: 3 October 2018; Accepted: 19 October 2018; Published: 24 October 2018 Abstract: A series of trials to fusion weld commercially pure titanium (CPTi) to stainless steel 304 (SS304) have been conducted using laser beam welding (LBW) and gas tungsten arc welding (GTAW). Neither technique produced adequate weld joints with LBW showing a more promising result, while GTAW yielded separation of the workpieces immediately after welding. Cracking and fracturing took place mainly on the SS304 side, which was explained by the differences in the materials’ thermal properties. Various intermetallic phases formed during welding that were identified using energy dispersive X-ray spectroscopy (EDS) and electron backscattered diffraction (EBSD) technique and were compared with an isothermal ternary phase diagram of Fe-Cr-Ti.
    [Show full text]
  • EXOTHERMIC FLUX FORGE WELDING of STEEL TUBULARS by Jeremy Joseph Iten
    EXOTHERMIC FLUX FORGE WELDING OF STEEL TUBULARS by Jeremy Joseph Iten Copyright by Jeremy Joseph Iten 2020 All Rights Reserved A thesis submitted to the Faculty and the Board of Trustees of the Colorado School of Mines in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Materials Science). Golden, Colorado Date Signed: Jeremy Joseph Iten Signed: Dr. Michael Kaufman Thesis Advisor Golden, Colorado Date Signed: Dr. Eric Toberer Professor and Program Director Materials Science ii ABSTRACT Welding processes inevitably alter the local microstructure and in turn affect the properties. For many grades of steels that require high strength, ductility, and toughness, it is difficult to maintain this combination of properties after welding. While full part heat treatments can sometimes be used to recover the microstructure and properties, this approach is impractical for welding of tubular strings in service. Therefore, advanced welding and localized post weld heat treatment methods are needed that can economically produce high integrity welds in tubular strings while maintaining strength, ductility, and toughness property requirements. A novel exothermic flux forge welding method is introduced for solid-state welding of steel tubulars and aspects of the development are discussed including constituent and heating rate effects on self- propagating high-temperature synthesis of metal and oxide products. The exothermic flux forge welded process was investigated for solid-state welding of a high strength low alloy (HSLA) steel and American Petroleum Institute (API) Q125 grade high-strength casing with a 14-inch (355.6 mm) outer diameter and 0.866-inch (22 mm) wall thickness. Post weld heat treatment approaches, including a multi-step heat treatment that included an intercritical heating stage, were investigated on the welded steel for their effects on microstructure and properties.
    [Show full text]
  • Solid State Welding and Application in Aeronautical Industry
    ISSN 2303-4521 PERIODICALS OF ENGINEERING AND NATURAL SCIENCES Vol. 4 No. 1 (2016) Available online at: http://pen.ius.edu.ba Solid State Welding and Application in Aeronautical Industry Enes Akca*, Ali Gursel International University of Sarajevo Faculty of Engineering and Natural Sciences Sarajevo, Bosnia and Herzegovina [email protected], [email protected] Abstract In this study solid state welding andapplication in aeronautic industryhave been researched. The solid state welding technicisused in the industrial production fields such as aircraft, nucleer, space industry, aeronautic industry, ect., actually solid state welding is a process by which similar and dissmilar metals can be bonded together. Hence a material can be created as not heavy but strong strength. Beside, advantages and disasvantages of solid state welding have been discussed. Also the diffusion welding and friction welding which belong to the solid state welding is obsevered in aeronautic industry. Keywords: solid state welding, aeronautic industry,diffusion welding, dissimilar materials 1 Introduction Welding is a metal joining process which produces Disadvantages of Solid State Welding: coalescence of metals by heating them to suitable Internal stresses, distortions and changes of micro- temperatures with or without the application of pressure structure in the weld region, or by the application of pressure alone, and with or Harmful effects: light, ultra violate radiation, fumes, without the use of filler material. Basically, welding is high temperature, used for making permanent joints. It is used in the manufacture of automobile bodies, aircraft frames, Also there are many kinds of welding processes; railway wagons, machine frames, structural works, tanks, Arc welding; furniture, boilers, general repair work and ship building.
    [Show full text]
  • Fusion Welding PM Components for Automotive Applications
    Fusion Welding P/M Components for Automotive Applications Jack A. Hamill, Jr. - Hoeganaes Corporation Frank R. Manley and David E. Nelson AC Rochester Division, GM Corporation SAE Technical Paper 930490 Presented at SAE International Congress Detroit, MI., March 1-5, 1993 ABSTRACT The paper identifies welding methods that are most often used to join P/M automotive components. Various weld procedures associated with the different methods are discussed. Examples are presented along with appropriate process information. A more detailed application development involves Gas Tungsten Arc welding a stainless P/M exhaust bushing to a wrought stainless steel tube. INTRODUCTION New automobile design goals focus on reducing vehicle weight along with improving structural integrity and safety standards while concurrently reducing manufacturing and assembly costs. The ability to satisfy the new design criteria will require manufacturing techniques along with new materials that exhibit increased strength, greater durability, better quality and lower costs. These characteristics parallel the attributes of powder metal (P/M) parts which continue to replace other methods of manufacture for use in various automotive applications. A significant number of P/M parts have been successfully fusion welded using joining processes common to the automotive industry. This has extended the use of P/M parts in vehicles by increasing the possibility of producing more complex components than could previously be achieved with conventional die pressed geometries. Additional discussion will focus on the P/M characteristics that impact weldability along with identifying common P/M welding procedures and techniques. The development of a welded 409 Cb stainless P/M exhaust component by AC Rochester will also be reviewed.
    [Show full text]
  • Friction Welding for Cladding Applications: Processing, Microstructure
    FRICTION WELDING FOR CLADDING APPLICATIONS: PROCESSING, MICROSTRUCTURE AND MECHANICAL PROPERTIES OF INERTIA FRICTION WELDS OF STAINLESS STEEL TO LOW CARBON STEEL AND EVALUATION OF WROUGHT AND WELDED AUSTENITIC STAINLESS STEELS FOR CLADDING APPLICATIONS IN ACID- CHLORIDE SERVICE by Nathan Switzner Copyright by Nathan Switzner 2017 All Rights Reserved A thesis submitted to the Faculty and the Board of Trustees of the Colorado School of Mines in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Metallurgical and Materials Engineering). Golden, Colorado Date _______________________________ Signed: _______________________________ Nathan Switzner Signed: _______________________________ Dr. Zhenzhen Yu Thesis Advisor Golden, Colorado Date _______________________________ Signed: _______________________________ Dr. Angus Rockett Professor and Head George S. Ansell Department of Metallurgical and Materials Engineering ii ABSTRACT Friction welding, a solid-state joining method, is presented as a novel alternative process step for lining mild steel pipe and forged components internally with a corrosion resistant (CR) metal alloy for petrochemical applications. Currently, fusion welding is commonly used for stainless steel overlay cladding, but this method is costly, time-consuming, and can lead to disbonding in service due to a hard martensite layer that forms at the interface due to partial mixing at the interface between the stainless steel CR metal and the mild steel base. Firstly, the process parameter space was explored for inertia friction butt welding using AISI type 304L stainless steel and AISI 1018 steel to determine the microstructure and mechanical properties effects. A conceptual model for heat flux density versus radial location at the faying surface was developed with consideration for non-uniform pressure distribution due to frictional forces.
    [Show full text]
  • A Critical Review of Friction Stir Welding Process
    DAAAM INTERNATIONAL SCIENTIFIC BOOK 2015 pp. 249-266 Chapter 22 A CRITICAL REVIEW OF FRICTION STIR WELDING PROCESS VERMA, S. M. & MISRA, J.P. Abstract: Friction stir welding (FSW) is a permanent type solid state joining process which is increasing rapidly for joining different metal alloys and non-metals in manufacturing industries especially aerospace, marine, spacecraft, automotive, etc. In present scenario the welding of metal alloys are replaced by FSW owing to its unique features over fusion welding processes, i.e. reduced porosity defect, reduced heat affected zone (HAZ), no requirement of shielding gas, ecofriendly, reduced distortion, etc. In this chapter, a critical evaluation of critical aspects of friction stir welding namely process principle, metallurgical and mechanical aspects; effect of preheating and nano-particle inclusion have been discussed. Difficulties and other issues related to FSW are also addressed to provide a guideline to global research community to carry out extensive research in this field. Key words: Solid-state welding, friction stir welding, preheating, quenching, nano- particle inclusion Authors´ data: Verma, S[hubham], M[eenu] & Misra, J[oy] P[rakash], Mechanical Engineering Department, National Institute of Technology Kurukshetra, India, [email protected]. This Publication has to be referred as: Verma, S[hubham] & Misra, J[oy Prakash] (2015). A Critical Review of Friction Stir Welding Process, Chapter 22 in DAAAM International Scientific Book 2015, pp.249-266, B. Katalinic (Ed.), Published by DAAAM International, ISBN 978-3-902734-05-1, ISSN 1726-9687, Vienna, Austria DOI: 10.2507/daaam.scibook.2015.22 Verma, S. & Misra, J. P.: A Critical Review of Friction Stir Welding Process 1.
    [Show full text]
  • A Brief Introduction to Joining and Welding
    Chapter 1 Introductory Chapter: A Brief Introduction to Joining and Welding Mahadzir Ishak Additional information is available at the end of the chapter http://dx.doi.org/10.5772/64726 1. Introduction Joining is an important process in a number of industries, such as aerospace, automotive, oil, and gas. Many products cannot be fabricated as a single piece, so components are fabricated first and assembled later. Joining technology can be classified as a liquid-solid-state process and mechanical means. Liquid-solid-state joining includes welding, brazing, soldering, and adhesive bonding. Mechanical joining includes fasteners, bolts, nuts, and screws. Metal joining is a process that uses heat to melt or heat metal just below the melting tempera‐ ture. Joining metal by fusion is known as fusion welding. Without fusion, the process is known as solid-state welding. Fusion welding includes arc welding and laser welding, Whereas solid- state welding such as friction stir welding (FSW) where process occurred below the melting temperature. 2. Fusion welding (arc welding) Fusion welding is known as non-pressure welding, in which edge samples to be joined with the filler metal are heated above the melting points to create a weld pool and allow solidifica‐ tion. Gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) are categorized under fusion welding. GTAW and GMAW are mostly used by the welder to weld both ferrous and non-ferrous metals. In fusion welding, inert gases, such as argon (Ar), helium (He), and carbon dioxide (CO2), are used for surrounding the electrode and molten metal from the welded metal.
    [Show full text]
  • 1 Fusion Welding Processes
    PART I Introduction 1 Fusion Welding Processes Fusion welding processes will be described in this chapter, including gas welding, arc welding, and high-energy beam welding. The advantages and dis- advantages of each process will be discussed. 1.1 OVERVIEW 1.1.1 Fusion Welding Processes Fusion welding is a joining process that uses fusion of the base metal to make the weld. The three major types of fusion welding processes are as follows: 1. Gas welding: Oxyacetylene welding (OAW) 2. Arc welding: Shielded metal arc welding (SMAW) Gas–tungsten arc welding (GTAW) Plasma arc welding (PAW) Gas–metal arc welding (GMAW) Flux-cored arc welding (FCAW) Submerged arc welding (SAW) Electroslag welding (ESW) 3. High-energy beam welding: Electron beam welding (EBW) Laser beam welding (LBW) Since there is no arc involved in the electroslag welding process, it is not exactly an arc welding process. For convenience of discussion, it is grouped with arc welding processes. 1.1.2 Power Density of Heat Source Consider directing a 1.5-kW hair drier very closely to a 304 stainless steel sheet 1 1.6mm ( /16 in.) thick. Obviously, the power spreads out over an area of roughly 3 4 FUSION WELDING PROCESSES 50mm (2in.) diameter, and the sheet just heats up gradually but will not melt. With GTAW at 1.5kW, however, the arc concentrates on a small area of about 1 6mm ( /4 in.) diameter and can easily produce a weld pool.This example clearly demonstrates the importance of the power density of the heat source in welding. The heat sources for the gas, arc, and high-energy beam welding processes are a gas flame, an electric arc, and a high-energy beam, respectively.
    [Show full text]
  • Welding of Platinum Jewellery Alloys COMPARISON of FUSION, LASER and SPOT WELDING
    DOI: 10.1595/147106707X171954 Welding of Platinum Jewellery Alloys COMPARISON OF FUSION, LASER AND SPOT WELDING By Duncan Miller, Katyusha Vuso, Penny Park-Ross and Candy Lang* Centre for Materials Engineering, University of Cape Town, Rondebosch 7701, South Africa; *E-mail: [email protected] The relatively recent application of laser welding and spot welding to platinum has supplemented the traditional joining techniques of conventional welding and brazing with a gas torch. Several recent publications (1–3) have promoted the use of laser welding, because of the superior strength of the joins compared with that of joins by conventional welding and brazing. In this paper we compare welds in three different platinum alloys, produced with three different welding techniques: conventional welding, laser welding and spot welding. The welds joining cold-rolled bars were performed by jewellers operating in their own workshops. The extents of the heat affected zones and consequent decrease in hardness were assessed in our laboratory. Laser and spot welding produced very narrow heat affected zones, with correspondingly narrow regions of diminished hardness, while the conventional welding resulted in samples being annealed and softened for their full lengths. Complete joining was difficult to achieve by laser and particularly spot welding, which could be problematic in joining thicker sections. With this knowledge, jewellers can design appropriately to take advantage of the novel joining techniques. Welding Techniques and laser welds can be made on complicated parts, Various joining techniques are theoretically between dissimilar metals, and close to set stones available to the platinum jeweller, including tradi- without damaging them (3).
    [Show full text]
  • Fundamentals of Welding
    FUNDAMENTALS OF WELDING 1- INTRODUCTION The term joining is generally used for welding, brazing, soldering, and adhesive bonding, which form a permanent joint between the parts—a joint that cannot easily be separated. The term assembly usually refers to mechanical methods of fastening parts together. Some of these methods allow for easy disassembly, while others do not. We begin our coverage of the joining and assembly processes with welding, Welding is a materials joining process in which two or more parts are coalesced at their contacting surfaces by a suitable application of heat and/or pressure. Many welding processes are accomplished by heat alone, with no pressure applied; others by a combination of heat and pressure; and still others by pressure alone, with no external heat supplied. In some welding processes a filler material is added to facilitate coalescence. The assemblage of parts that are joined by welding is called a weldment. Welding is most commonly associated with metal parts, but the process is also used for joining plastics. Our discussion of welding will focus on metals. Welding is a relatively new process (Historical Note 29.1). Its commercial and technological importance derives from the following: 1- Welding provides a permanent joint. The welded parts become a single entity. 2- The welded joint can be stronger than the parent materials if a filler metal is used that has strength properties superior to those of the parents, and if proper welding techniques are used. 3- Welding is usually the most economical way to join components in terms of material usage and fabrication costs.
    [Show full text]