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PWL#073 - GAWDAwiki: Interactive Resource, Welding Lead, Filler Metals for Graphite,SAW Optimization September 01, 2009 |
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| We hope you will find this Letter interesting and useful. Let us know what you think of it. PWL#073 - GAWDAwiki: Interactive Resource, Welding Lead, Filler Metals for Brazing Graphite and Carbon/Carbon Composites, Submerged Arc Welding Optimization, Interview with William Reid, Friction Surfacing, Brazing Graphite and more... DON'T USE REPLY to send us your messages! Use Contact Us instead. This publication brings to the readers practical answers to welding problems in an informal setting designed to be helpful and informative. You are urged to pass-along this publication to your friends, if you like it, and if you want to help them. If you received this from a friend and if you like what you read, please subscribe free of charge and you will also receive a bonus book on Practical HARDNESS TESTING Made Simple. Note: References to articles or other documents are given here in one of two forms. If the links are "live" (usually underlined or otherwise highlighted) they are operated with a click of the mouse. If they are URL's (Uniform Resource Locator), which is the analogue of an address, they begin with "http://..." or "www.". These are not live and must be copied and pasted entirely into the browser (after having been selected with the mouse or otherwise). If they are long they may be displayed in two or more lines. In that case one has to care that the URL be copied completely in a single line without any space, and Enter.
2 - Article - Welding Gases 3 - How to do it well: Welding Lead 4 - Filler Metals for Brazing Graphite and Carbon/Carbon Composites 5 - Online Press: recent Welding related Articles 6 - Terms and Definitions Reminder 7 - Article - Submerged Arc Welding Optimization 8 - Site Updating: Friction Surfacing, Brazing Graphite 9 - Short Items 10 - Explorations: beyond the Welder 11 - Contributions: Interview with William Reid 12 - Testimonials 13 - Correspondence: a few Comments 14 - Bulletin Board 1 - Introduction This Issue 73 of Practical Welding Letter is rich with readers' contributions, which make it more lively and interesting. We thank all those who participated and ask all others to join in. This newsletter opens with a press release kindly submitted by a member of an Association of Distributors providing information and help on welding gases. Our readers can search their site and pick up all the assistance they may need on the subjects they deal with. Then we publish a comment, a welcome initiative, sent by one of our kind readers who wished to share his experience with this audience. I would like to encourage all our other readers: write a note on what you know and your fellow readers will be grateful for the opportunity to learn from you. Brazing Graphite and Carbon/Carbon composites may be a specialized activity, important only for selected segments of industrial production working on advanced applications. Nevertheless open minded welders have only to gain from uncommon information even if they are not going to apply it immediately. In this section a few brazing filler metals are listed for reference. The next article on Submerged Arc Welding Optimization was submitted by a reader and relates the practical experience and the benefits obtained from testing some new ways of solving production problems. This case history contribution is highly appreciated, and it is certain to interest more than one reader. Again, whoever is ready to share personal experience is invited to do so by writing a short note. In the Contributions section we publish an interview kindly sent us by a reader. Many other readers who promised to participate are invited to send us their own as soon as possible. All other standard sections appear at their usual places. Your valued personal input is actively sought for. Don't use REPLY. Send your notes using the form in the Contact Us page. 2 - Article - Welding Gases Readers may recall that our last Mid Month Bulletin (PWL#072B), dealt with Resources on Welding Gases. Hoping to provide a useful service to our readers, we reproduce hereafter with minor omissions the following Press Release on the same subject, kindly submitted by Mr. Jeffrey Charboneau of GAWDA. August 21, 2009
GAWDAwiki: The Gases and Welding Distributors Association (GAWDA) has introduced GAWDAwiki, a comprehensive online information portal featuring gases and welding industry news and information. GAWDAwiki is a quick-reference Web site with videos, white papers, spec sheets, industry news, a searchable buyers guide and an ever-expanding encyclopedia of gases and welding terminology. Designed with users in mind, GAWDAwiki is an invaluable business tool for allied industries as well. In it, the following information can be found:
An online lexicon of industry terminology. An industry resource.
Why Visit www.GAWDAwiki.org? Contact: Jeffrey Charboneau / 315-445-2347 / jeff@datakey.org About GAWDA 3 - How to do it well: Welding Lead The following comment was sent by Mr. Timothy Lynch Date: 12 Aug 2009 Sir: I read with interest your treatise on welding lead. Well done, except that we use oxygen and hydrogen mix to weld lead (statuary). The reason is that oxy-acetylene will cause the lead puddle to "pop" or blow out, sometimes causing burns if the spatter lands on your skin. This never occurs with oxy-hydrogen mix. All other problems remain as described. s/ Tim Lynch I would like to thank the Author of this note for his important contribution, likely to interest whoever happens to work with lead. He was referring to my page on Joining Lead Tin Zinc. 4 - Filler Metals for Brazing Graphite and Carbon/Carbon Composites In the recent Website page on Brazing Graphite, reported further down in Section 8, Filler Metals were listed for applications used at low or moderate temperatures. The data displayed there are shown in Catalogs supplied by commercial Manufacturers. A few additional materials (not reported) are listed in Table 21.6 at page 396 of the AWS Brazing Handbook, Fifth Edition. From the same Handbook we report hereafter selected data as follows.
Table 2, (from Table 21.8 at page 398 of the above Handbook), refers to applications used at ultra high temperatures for limited times. Testing is essential for determining the suitability of proposed solutions to actual usage.
For more information on Brazing Graphite and Carbon/Carbon Composites, interested readers are urged to consult the AWS Brazing Handbook: AWS BRH
5 - Online Press: recent Welding related Articles Four Subs examined for Troubles with Bolts Business Tips: Laser Welding Ins And Outs You Don't Know Proper Welding Safety is No Accident Shop Gains Productive Edge with Robotic Welding TWI Connect - July August 2009 6 - Terms and Definitions Reminder Electrode Mushrooming is the enlargement and deformation to mushroom shape of a resistance electrode tip, caused by heat and pressure. Inverter power sources first rectify line frequency and then use inverter circuits to produce high frequency alternating current. The high frequency high voltage is reduced with a transformer and then rectified to obtain the pulsed current output. Operating on high frequency allows a greatly reduced size of transformer with much reduced losses. Oxyhydrogen Welding is an oxyfuel gas welding process using hydrogen. See Section 3 above. Pickling is the chemical removal of surface oxides (scale) and other contaminants such as dirt, from metals by immersion in an aqueous acid solution. Thermal Spraying is a group of processes, based on an energetic thermal source (flame, arc or plasma), used to deposit layers of finely divided droplets on a substrate. Underwater Welding is the complex of methods and techniques used to perform welding operations under the water level, either in a wet environment or in a pressurized dry space. Vickers Hardness Testing is the method of evaluating hardness by measuring the diagonals, projected on the tested surface, of the imprinted trace (indentation) left by a square based pyramidal diamond indenter applied on the surface with definite load for a given time. Wave Soldering is an automatic soldering process where printed circuits are passed through a wave or fountain of molten filler solder, created by a pump at the bottom of the solder tank. 7 - Article - Submerged Arc Welding Optimization Mr. Naddir M. Patel from Calgary, Alberta, Canada kindly submitted the following information. We thank him for his very interesting contribution. Submerged arc welding is considered one of the most economical and efficient methods of welding. Yet, in the search for fine tuning this process, obvious solutions have been ignored at the expense of exotic and expensive welding heads and power sources. I ran a Submerged Arc Welding flux manufacturing facility in Mumbai, India (Silico Products). Optimizing clients SAW operations was therefore part and parcel of the sales efforts. One thing I noticed that, in-spite of the SAW process being the most efficient weld metal depositor, there was a tremendous time loss between processes. There were also defects of "burn-through" because welders were not proactively measuring the inter-pass temperatures. The ideal Poke-Yoke (fool proofing) solution was therefore to somehow control the heat input to the parent metal. Re-training welders and/or re-qualifying weld procedures would also pump up the capital costs of the project. This high capital investment would still have limited versatility in a typical multi-tasking weld shop with circumferential welds changing from 6" to 42" diameters in various plate thicknesses. A literature survey, however, indicated that increasing electrode extension would seem to be the ideal remedy for increasing production rates and decreasing the heat input.
Whereas earlier attempts to increase electrode stick out (extension) were not very successful or consistent, we located a company by the name of Tipmate that made ceramic nozzles that guided the hot wire without jamming it. It is a simple ceramic nozzle that is screwed onto the contact tip of the SA (submerged arc welding) head. The device allows electrode extensions of 3" or more without wire straying. Importantly arc wandering was eliminated, weld penetration was adequate and weld beads were perfect. As welding parameters were not changed (except for a very small voltage increase) there was no need re-qualify weld procedures. We found the ceramic nozzle directly screws onto the contact tip and can be easily and quickly changed based on our wire/electrode diameter. Guided by the vendor we increased the electrode extension in increments to yield deposition rate increases of 45% without any RT (radiographic testing) defects showing up. As the heat affected zone was narrower, we designed narrower grooves for greater efficiencies and less distortion. For normal welds we found a 2.4mm (3/32") electrode with a 56mm (2 1/4") extension could be used over a range of thicknesses. Heavy walled welds were completed with 4mm (5/32") [electrode]. All these tests were conducted at various (welding flux) customer locations and a wide range of groove welding applications for both MS and SS (mild steel and stainless steel) materials, in a 350-650A range. Although I am based in Canada now, I cannot disclose the companies' names for proprietary reasons. In summary, with weld deposition rates increasing by 50% and minimal change in existing welding parameters, it became obvious that this was a force multiplier not only in terms of production throughput, but also in a drastic decrease in burn-throughs and subsequent repair....all with no capital expense. Comments are welcome. Readers with similar or different practical experiences likely to interest our audience are urged to send us their notes using the Contact Us form. 8 - Site Updating: Friction Surfacing, Brazing Graphite The two Pages of this Month added to the website relate information on specialized processing. The first, on Friction Surfacing, presents a not much known process whose unique advantages could contribute to cost effective applications where feasible. Being this a cold welding method, it is suitable also for incompatible combinations that would not tolerate fusion welding. The second, on Brazing Graphite and Carbon/Carbon Composites, outlines the complex procedures that must be adopted for successful realizations. While some types of filler metals are listed in the above page, other types suitable for applications operating at higher temperatures, are listed in Section 4 above. Readers interested in being promptly informed of the publication of new pages are invited to subscribe to the RSS feed as explained in every page of the website under the NavBar. The Site Map can be consulted for finding specific pages. Comments and feedback are welcome. Don't use REPLY. Use the Contact Us form instead. 9 - Short Items 9.1 - Continuous Casting is a technique in which a cast shape is continuously withdrawn through the bottom of the open mold as it solidifies. Therefore its length is not determined by mold dimensions. It is used mainly to produce semifinished mill products such as billets, blooms, ingots, slabs, strip, and tubes. 9.2 - Dezincification is called that type of corrosion in which zinc is selectively leached from zinc-containing alloys leaving a relatively weak layer of copper and copper oxide. Most commonly found in copper-zinc alloys (brasses) containing less than 85% Cu, after extended service in water containing dissolved oxygen. 9.3 - Electrodeposition is the deposition of a conductive material from a plating solution onto a conductive item by the application of electrical current. In electrolytic refining it is the deposition of metallic ions on an electrode by passing electric current through an electrolyte. 9.4 - Interstitial Solid Solution is a type of solid solution that sometimes forms in alloy systems having two elements of widely different atomic sizes. Elements of small atomic size, such as carbon, hydrogen, and nitrogen, often dissolve in solid metals to form this solid solution. The space lattice remains almost unchanged, and the atoms of carbon, hydrogen, and nitrogen occupy the spaces or interstices between the main metal atoms. 9.5 - Piezoelectric Effect is the reversible interaction, exhibited by some crystalline materials, between an elastic strain and an electric field. The application of an oscillating electric field through suitable electrodes, to a piezoelectric crystal induces in it volume changes, used to generate sonic or ultrasonic waves. The direction of the strain depends on the polarity of the field and vice versa. 9.6 - Refractory Metal is described as a metal having an extremely high melting point and low vapor pressure like niobium, tantalum, molybdenum, tungsten, and rhenium. 10 - Explorations: beyond the Welder Prioritize the Carbon Strategy Robo-Bats May Be Next Remote Control Flyers Seeing below the Surface A Sonic Boom in the World of Lasers The Modern History of Computing 11 - Contributions: Interview with William Reid Name: William Reid Questions and Answers: Q: What did appeal to you when you first considered welding as your Career? Q: How did you start your welding Career? Q: Did you plan to achieve definite Career milestones in a given time frame? Q: In which field of welding are you active? Q: Which were your major achievements during your Career in welding? Q: Which of your achievements procured to you the highest satisfaction? Q: Which is the most important lesson you would like to transmit to young
welders? Q: Which goals should a young welder aim to reach? Q: Do you foresee interesting developments likely to change the welding
profession? Q: How would you invite young people to consider welding as their Career?
This is the first Interview received and published here. Thanks to William Reid for having shared with us his thoughts on some aspects of his welding experience. This note is most interesting to me. I am sure we can read on many other interesting stories if the readers who, answering to the recent questionnaire, expressed their readiness to be interviewed, will find the time to send us their answers to the proposed or to other questions they may feel more important. I would like to urge everyone to participate in these interviews. 12 - Testimonials From: Eli Minoff Excellent issue !!!
From: DAN WALTER THANKS SO MUCH. 13 - Correspondence: a few Comments 13.1 - After so many years on the Web I still receive requests to supply offers for equipment or consumables. It is maybe flattering but off the mark. 13.2 - A hopeful student addressed to me a list of a dozen questions, to answer which I should have written a handbook on welding. I listed for him a few of the fundamental and very good books available in any serious library. He should study them in depth for a long time and then he will know what can and what cannot be answered in a short letter. 13.3 - A reader asks for the maximum allowable wind speed for acceptable welding using FCAW. I found only suggestions that wind shields should be always in place. If any of the readers is aware of specific requirements limiting the wind speed to a certain value, please let me know and I will publish the information.
14 - Bulletin Board 14.1 - Free TIP TIG Workshop at the Philadelphia Naval Yard. 14.2 - GAWDA Annual Meeting (See Section 2 above) 14.3 - Titanium 2009 Conference and Exposition 14.4 - 25th ASM Heat Treating Society Conference and Exposition 14.5 - Materials Science & Technology 2009 Conference & Exhibition
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