1 Reference Photo Guide for Stainless Steel Welds Materials and Applications Series, Volume 14. Reference Photo Guide FOR Stainless Steel Welds . Euro Inox Euro Inox is the European market development asso- Full members ciation for Stainless Steel . Acerinox Members of Euro Inox include: European Stainless Steel producers;. Aperam national Stainless Steel development associations; development associations of the alloying element industries. Outokumpu The prime objectives of Euro Inox are to create aware- ness of the unique properties of Stainless Steel and ThyssenKrupp Acciai Speciali Terni to further its use in existing applications and in new markets. To achieve these objectives, Euro Inox organ- ThyssenKrupp Nirosta ises conferences and seminars and issues guidance in printed and electronic form, to enable architects, designers, specifiers, fabricators and end users to Associate members become more familiar with the material.
2 Euro Inox Acroni also supports technical and market research. British Stainless Steel Association (BSSA). Cedinox Centro Inox Informationsstelle Edelstahl Rostfrei International Chromium Development Association (ICDA). International Molybdenum Association (IMOA). Nickel Institute Paslanmaz elik Derne i (PASDER). Polska Unia Dystrybutor w Stali (PUDS). Swiss Inox ISBN 978-2-87997-332-6 Reference Photo Guide FOR Stainless Steel Welds . Contents Reference Photo Guide for Stainless Steel Welds Introduction 2. First Edition 2011 How and where to use this Photo Guide 2. (Materials and Applications Series, Volume 14) About welding process selection 3. Euro Inox 2011 Productivity 3. Different types of weldment surface appearance and how to improve the result 4. Quality levels demonstrated 5.
3 Post-weld treatment 5. Importance of geometrical deviations 5. Trained welders 6. Welding costs productivity 6. Editor Further reading 6. Euro Inox Diamant Building, Bd. A. Reyers 80. 1030 Brussels, Belgium Tel.: +32 2 706 82 67. Fax: +32 2 706 82 69. E-mail: Internet: Author Bj rn Holmberg, Avesta Research Centre, Avesta (S). Acknowledgements Euro Inox wishes to thank BSSA for its critical reading of the draft publication. Copyright notice Photos This work is subject to copyright. Euro Inox reserves Outokumpu, Avesta (S) all rights of translation in any language, reprinting, re-use of illustrations, recitation and broadcasting. No Disclaimer part of this publication may be reproduced, stored in Euro Inox has made every effort to ensure that the a retrieval system or transmitted in any form or by any information presented in this document is techni- means, electronic, mechanical, photocopying, record- cally correct.
4 However, the reader is advised that the ing or otherwise, without the prior written permission material contained herein is for general information of the copyright owner, Euro Inox. Violations may purposes only. Euro Inox and its members specifically be subject to legal proceedings, involving monetary disclaim any liability or responsibility for loss, dam- damages as well as compensation for costs and legal age, or injury, resulting from the use of the informa- fees, under Luxembourg copyright law and regulations tion contained in this publication. within the European Union. 1. Reference Photo Guide FOR Stainless Steel Welds . Introduction Welding is a particularly common fabrication In architectural applications, much care is technique for Stainless Steel . Most stain- taken to ensure the good appearance of less Steel grades are easy to weld.
5 If prop- Welds in visible areas. Weld quality in non- erly done, Welds can be as strong, corrosion- visible fabrication parts is not always paid resistant and visually appealing as the base the necessary attention. These areas may be material. exposed to pollutants, typically chlorides and sulphur from exhaust gases, coastal atmos- However, inadequate Welds can have unwant- phere or aerosols of de-icing salt. However, ed consequences: unlike the decorative side, they may never be The corrosion resistance of the fabrication inspected and cleaned, and especially if they can be compromised in the welded area are sheltered and not washed by rain, accu- and lead to problems later. mulation of corrosive deposits is possible. Structural problems may occur. Good weld quality is therefore important in In decorative applications, it can become hidden as well as visible joints.
6 Impossible to grind and polish the Welds to the requested aesthetic standards. How and where to use this Photo Guide The aim of this Photo Guide is to give visual The brochure does not focus on defect types. acceptance criteria showing different weld- These can be studied in ISO 5817 1. The reader ing procedures, degrees of surface finishing should also bear in mind that visual inspec- and weld geometries. It will help purchasers, tion cannot replace micrographic examina- architects, designers, inspectors and engi- tion. neers choose suitable welding procedures for their applications. The Photo Guide can also The photos show an overview of the weld be used as a Reference document for contract in the as-welded condition;. agreements, so misunderstandings and dis- in post-weld cleaned condition.
7 Putes after final inspection can be avoided. as a close-up of the surface (to better illus- trate rippling and surface phenomena);. The focus of this document is on the appear- as a cross-section through the weld (to show ance of the cap run. In many applications, the geometry of the weld reinforcement). the appearance of the root side is crucial, if it is exposed to liquid or gaseous media. This, however, exceeds the scope of the present Photo Guide . 1 ISO 5817:2003 Welding Fusion-welded joints in Steel , nickel, titanium and other alloys (beam welding excluded) Quality levels for imperfections 2. Reference Photo Guide FOR Stainless Steel Welds . About welding process selection Seven different welding procedures in If GTAW or GMAW welding is used, the liquid three quality levels are shown here.
8 In weld pool is protected from the surrounding each case, the most typical parameters for atmosphere by shielding gas (Ar or Ar + O2/ CO2). the welding procedure are used respec- tively. For each test, the parameters are When GMAW welding is carried out, the arc mode listed. Other combinations of parameters might play an important role in the appearance. can also be selected to produce the same In the tests underlying the present publication, weld appearance. only short-arc and spray-arc have been used. The welding methods presented here are: The appearance of the weld reinforcement Gas Tungsten Arc Welding (GTAW) or is strongly dependent on the welding proce- Tungsten Inert Gas Arc Welding (TIG), here dure. It is generally accepted that an auto- called GTAW. matic process produces a smoother surface Gas Metal Arc Welding (GMAW) or Metal- than a manual welding procedure.
9 The GTAW, Arc Inert Gas Welding (MIG), Metal-Arc laser and plasma processes normally result Active Gas Welding (MAG), both here called in much smoother surfaces than SMAW and GMAW. Both spray- and short-arc modes GMAW short-arc processes. The most favour- are used in this Guide . able position to achieve a flat, smooth weld is Shielded Metal Arc Welding (SMAW) or a slightly inclined position. Manual Metal Arc (MMA), here called SMAW. Flux-Cored Arc Wire Welding (FCAW), here Slag protects the weld pool if SMAW or FCAW. called FCAW. is used. Productivity When a welder chooses a welding method, not suitable for in-situ welding. If the sheet/. the appearance of the weld is not the only tube material is thinner than about 1 mm, thing that matters. Another very important the most commonly used welding method is factor is the level of productivity of the select- GTAW.
10 In practice, manual welding is very dif- ed welding process. As an example, GMAW ficult to perform with other methods without and FCAW are faster processes than GTAW burning through. If the material is very thin, (in kg/h), see Figure 1. Laser and plasma are overlap joints can serve as an alternative to normally fully automatic processes that are butt Welds . 3. Reference Photo Guide FOR Stainless Steel Welds . Different types of weldment surface appearance and how to improve the result The most common visible phenomena on can normally only be removed by grinding. Welds , beside conventional weld defects, are: varying coarseness of rippling; The geometrical profile of the weld reinforce- sticking surface slag; ment can influence weldment properties. A. concave/convex reinforcement; convex bead with a sharp toe angle will reduce spatter.