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PWL#120 - Optimizing Material Specifications and Welding Protocols, Welding 1018 to 4140,New filler August 01, 2013 |
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| We hope you will find this Letter interesting and useful. Let us know what you think of it.
The Importance of Optimizing Material Specifications and Welding Protocols, Welding 1018 to 4140, Stronger New Filler Metal 4943 for Aluminum Alloys, Update on Inverter Technology for GTAW, A New Fusion Cladding Process, Flood Welding (R) and Forge Welding (R) and much more... PWL#120
The Mid July 2013 Issue of Practical Welding Letter, Bulletin 87, introducing Resources on Virtual Welding Training was not distributed by e-mail but it is available at Bulletin 87 and from the Welding Resources Page.
DON'T USE REPLY to send your messages! Use the Contact Us form instead.
This publication brings to the readers practical answers to welding problems in an informal setting designed to be helpful and
informative. We actively seek feedback to make it ever more useful and up to date. We encourage you to comment and to contribute your experience, if you think it may be useful to your fellow readers. You are urged to pass-along this publication to your friends, if you like it, and if you think it may 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. The addresses reported hereafter were live and correct at the time of their publication. There is no guarantee that they will always be so, because they are administered by the sources themselves and are under their control. Note: References to articles or other documents are given here in 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. If the information is important to you as we hope, you may save the selected pages in a suitable folder on your Computer for easy reference. You are welcome to forward this page to those of your friends who may profit of this information.
1 - Introduction 2 - Article - The Importance of Optimizing 3 - How to do it well: Welding 1018 to 4140 4 - Stronger Filler Metal 4943 for Aluminum Alloys 5 - Online Press: recent Welding related Articles 6 - Terms and Definitions Reminder 7 - Article: Update on Inverter Technology for GTAW 8 - Site Updating: Flood Welding (R) and Forge Welding (R) 9 - Short Items 10 - Explorations: beyond the Welder 11 - Contributions: A new Fusion Cladding Process 12 - Testimonials 13 - Correspondence: a few Comments 14 - Bulletin Board
(Sponsored Links)
2 - Article - The Importance of
Optimizing |
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Case Study:
Surface Hardness in carbon steel pressure vessel heads resulting in cost and time overrun.
A successful fabrication project involves conformance to code and client requirements, minimizing costs and keeping delivery within schedule.
Estimation, sales, design, purchase and fabrication must all dovetail seamlessly into one another.
The material specification
originates from the client, and the fabricator's responsibility is to build a quality vessel or piping module to the relevant code within the agreed time frame.
Any time or cost overrun due to logistical or quality issues can hurt the company’s profit margin calculated for the project.
Codes for procurement and fabrication of pressure vessels are very detailed but it is important not to treat them as quality plans.
The best way to ensure profit generation is through a first time right method based on a technically proficient project plan built on a foundation of benchmarked procedures and industrial experience.
In real life however, depending upon the technical skills of the project manager and his/her ability to run a tight ship, and plan proactively,
slip ups do happen which end up draining profitability.
Aside from the fabrication itself, things could go wrong in
purchasing, housekeeping, and realistic scheduling; each of which are critical to project profitability.
| Note: The relevant article on Process Optimization, was published (2) in Issue 102 of Practical Welding Letter for February 2012. Click on PWL#102 to see it. |
Generalized in my last article in PWL on the methodology of eliminating wastes in production, the following is an example of how things could go wrong; when there are deficiencies in the fabrication plan, such as poor housekeeping and/or shop floor co- ordination.
Background.
Plates for a sour service vessel were procured from a vendor based strictly on price.
Code compliance for meeting the minimum calculated plate thickness was ensured through an Ultrasonic Testing scan (UT).
On inward check, although all code requirements including Material Testing Certification reporting requirements were met, it was noticed that small corroded blisters on the plate surface, peeled away on wire brushing.
It was however decided to forward the plate for head forming and restore the surface through a SMAW (Shielded Metal Arc Welding or Stick) welding procedure to address base metal repair of imperfections at a later date.
On receipt of the formed heads, surface repair was carried out as per the parameters of the welding procedure.
Being winter time, the accelerated cooling rate and the possibility of quenching of the HAZ
(heat affected zone) due to the shop floor door opening multiple times was not factored into the production welding sequence.
Thus no pre-heating beyond the WPS (Welding Procedure Specification) mandated pre-heat of 50°F (10°C) was carried out, neither were blankets deployed to ensure maintenance of inter-pass temperature and slower HAZ cooling rate.
A hardness survey carried out after the surface repair indicated localized hard zones well above the client specifications. Welding raises the temperature of the HAZ above the lower critical temperature of steel and the air quenching resulted in pockets of un-tempered martensite.
Rather than subject the heads to some heat treatment or tempering, for reasons that are not clear, the project manager decided to carry out an acid etch and grind protocol.
Not only did this line of action delay the schedule, but grinding out the spots of un-tempered martensite ended up
reducing the plate thickness to the minimum required calculated thickness.
The casualty was quality and by extension the project profit.
In this article, following the principle that processes can be fool-proofed to override performance deficiencies that can occur from time to time, we will only address pro-active actions that a fabricator can take, beyond mere code conformance.
The action plan is based on incorporating best practices and industrial experience.
Examples include:
- NACE 8X194 - Materials and Fabrication Practices for New Pressure Vessels used in wet H2S Refinery Service
- NACE SP0472 - Standard Practice - Methods and Controls to prevent in-service Environmental Cracking of Carbon Steel Weldments in Corrosive Petroleum Refining Environments
- API RP 582 - Recommended Practice - Welding Guidelines for the Chemical, Oil, and Gas Industries
This would ensure manufacture of a quality product and avoid time and scheduling overruns.
The Importance of a Realistic WPS
Welding procedures must be fine-tuned and benchmarked to the shop conditions.
A Welding Procedure, qualified under ideal (indoor) conditions utilizing the services of the best welder in the shop, is a self-defeating proposition, as ideal conditions never exist on a shop floor.
The shop’s best welder would obviously expedite a successful weld procedure qualification; but unless each operational factor is benchmarked and there is 95% confidence that shop floor welding parameters would not deviate more than say 20% from each control limit set, this is not a realistic WPS, that is easily replicated in production.
In the heat affected zone (HAZ), maximum heat flows through the parent metal alongside the joint. The mechanical properties of the weld and HAZ are directly related to their microstructure.
Whereas the chemical composition of the weld depends on the alloying elements in the filler metal, the microstructure is dependent on the heat input, inter-pass temperatures, rate of cooling and the insulating and inclusion removal characteristics of the flux (consumable).
In this case, an accelerated cooling rate based on external conditions such as sudden temperature drop in winter, as well as the relative humidity which could quench the HAZ and negatively impact welding quality, were not factored in. As soon as the shop door is opened for material movement, there is a temperature drop and infiltration of humidity.
| Note: A short article on t8/5 was published (2) in Issue 51 of Practical Welding Letter for November 2007. |
Unless this cooling time (t8/5) is factored in, and pro-active measures such as use of insulating welding blankets are put in place to ensure maintenance of inter-pass temperatures and cooling rates matching those listed in the PQR (Procedure Qualification Record), the quality of the weld will be affected, in terms of:
- degraded microstructure,
- reduced impact strengths,
- localized high hardness zones, and by extension
- crack susceptibility in the HAZ.
Heat input is a very important welding variable that regulates the cooling rates in welds.
In situations where the cooling rate could be detrimental to the weld, countervailing measures such as pre-heating and the use of welding blankets can be applied.
Slowing the cooling rate allows more time for weld metal refinement to an optimal microstructure, minimizing the possibility of localized hardness or cracks.
Published data indicate that a higher heat input results in a coarse microstructure while a lower heat input results in a finer microstructure.
For example, in SAW (Submerged Arc Welding), the ideal heat input of 2.2-2.6 KJ/mm ensures formation of a microstructure with adequate strength.
An ideal WPS (Welding Procedure Specification) should, therefore, be one that incorporates the ideal heat input for the process and the weld configuration being used.
Similarly, controlling the width to depth ratio of weld joint to between 1.2 and 1.3 with the appropriate groove sizes can go a long way in preventing defects or discontinuities.
 |
The Importance of Material Chemistry and Microstructure.
Material procurement references codes such as ASME II1 should be complied with.
For pressure vessel quality carbon steels, the client usually fine tunes these specifications by limiting the percentage of elements such as C, Cb and V, as well as the CE (Carbon Equivalent).
Whereas it is common knowledge that the CE is directly proportional to tensile strength; inclusions and their relationship to S, O2 and H2 content is not emphasized. Inclusions, after all, cause voids which could initiate high hardness zones and cracks.
The procurement manager places an order for the material based on this data sheet. From the metallurgical perspective, however, specifying tighter control limits on plate chemistry based on industrial experience would go a long way in making fabrication processes such as deformation during rolling and forming, as well as welding less vulnerable to discontinuities or defects.
Typical Chemical Composition of ASTM/ ASME A516 Grade 70 is as in the following
| Element | Plate analysis % | Thickness |
| Carbon | 0.27 (max.) | <0.5" |
| " | 0.28 (max.) | 0.5"- 2" |
| " | 0.30 (max.) | 2"-4" |
| " | 0.31 (max.) | > 4" |
| Manganese | 0.85-1.30 | |
| Phosphorus | 0.035 (max.) | |
| Sulphur | 0.035 (max.) | |
| Silicon | 0.15-0.40 |
Section II: Materials - Part A - Ferrous Material Specifications
Section II: Materials - Part B - Nonferrous Material Specifications
Section II: Materials - Part D - Properties (Customary or Metric)
Industrial data indicate that
- Elements such as C, Mn and Si tend to decrease slightly, in the weld composition, as heat input increases.
Whereas a minimal lowering of C, within the control limits set for the pressure vessel quality steel is not detrimental, loss of Mn would affect the mechanical properties and loss of Si would reduce the resistance of the steel to oxidation (and the potential for porosity) during welding. - Steels with 0.15%-0.40% Si have been found to exhibit superior characteristics to those with <0.1%Si.
In this case whereas SA516-70N material specification is generally in the range of 0.15%-0.40%, requesting a Si content of, say, 0.3% minimum would increase the resistance to oxidation during welding. In effect this would ensure a smooth, inclusion free weld even if heat input is increased inadvertently. - Whereas AOD (Argon Oxygen Decarburization), VOD (Vacuum Oxygen Decarburization) and Ca treatment are routinely stipulated for pressure vessel quality plates, the S content which is a source of inclusions is not suitably
highlighted.
The same goes for O2 and H2 content. Total O2 content, after all, is directly proportional to the number of oxide inclusions.
During the rolling of steel plates, the existing inclusions breaks into a stringer or other pattern, or are simply dispersed in a soft matrix.
These dispersed inclusions have been shown to have a detrimental effect on impact properties of the steel.
Industrial experience however indicates that reducing the S content to below 0.002% effectively avoids the formation of sulfide inclusions.
Similarly O2 content below 20ppm and H2 content below 2ppm have been shown to minimise inclusion formation.As can be seen, blandly specifying S < 0.035% does meet code requirements.
However, based on industrial experience, this S content does not address the operational requirements of sour grade steels. One must therefore, pro- actively request the plate suppliers to provide material with as low a S content as possible.
In summary, a proactive approach of implementing best practices based on industrial experience to material and welding metallurgy would go a long way in ensuring timely delivery of a quality product best suited to the processing environment that it will be exposed to.
Questions or Comments can be addressed to the Author, directly or through PWL.
For further information see:
Arcelor Mittal USA
Plate A516 and A387 Pressure Vessels Steels: A Technical Overview
Arcelor Mittal.
PWL is grateful to the author, Naddir M. Patel, who honored this special Ten Years Anniversary Issue with an original, instructive and interesting Contribution, likely to teach a few things to those whose job is related to welding of heavy industrial installations.
3 - How to do it well: Welding 1018 to 4140
A query was recently received from a disgruntled reader on the problem exposed in the title above.
On the disagreeable experience I am expanding somewhat in section 13 below.
A thorough answer to the above question is available for all to see in my page:
www.welding-advisers.com/ Weld-FAQ.html
by scanning the titles until this one is reached.
By the way, checking FAQs before asking is recommended in the Contact Us form page.
 |
But the question was more complicated. The 1018 was a round bar carburized (for an unspecified thickness) and hardened to 55-58 RC. The 4140 was a flat bar 5/8" thick by 2.25" wide, hardened to 25RC.
The inquirer took pain in writing that the round bar was 1" diameter at the weld area and turned down to 1/2" where the actual wear takes place.
(No details on the motion were provided).
Unfortunately the weld joint was not described at all nor were the relative positions of the two bars.
Furthermore there was no hint at how the contraption was supposed to work.
Nevertheless it was stated that:
- We are already committed to the welding process of these parts.
- As most of the machining is finished, can you recommend a viable welding process?
- Pre and post heat?
- Type of weld?
- And typically how far from the weld would softening occur in parts of this configuration?
I asked for more details and for a sketch to study the options. As too often happens the correspondence was suddenly interrupted and the query abandoned, as if the question was not interesting any more or as if I had asked absurd requests.
As a general recommendation I would think that it is unwise to start machining without knowing how you will complete your construction. Welding is not an accessory to be appended at the end of the process. It is integral with fabrication, but has to be planned in advance in the correct sequence of events.
Among the possible ways out of the impossible situation described above one could have thought of delaying carburizing and hardening until after welding, or on performing brazing instead of welding, provided a suitable overlapping area could have been conceived, or if necessary, on mechanical fastening instead of welding.
If the function of the construction had been explained and if the welding joint had been described clearly, a suitable welding process could have been proposed, and adequate provisions could have been suggested to limit softening to the least volume possible, if necessary.
When will inquirers learn to ask properly?
4 - Stronger Filler Metal 4943 for Aluminum Alloys
The introduction of new aluminum alloys consumables is quite a rare event, as the previous one occurred 50 years ago with Alloy 4643.
In the article published at page 32 of the July 2013 issue of the Welding Journal, Tony Anderson, a renowned aluminum welding expert, reports the recent development of Alloy 4943.
This announcement comes after the lecture given by the same Author at the 8th Shipbuilding Conference, held on February 26, 2013.
The new alloy was developed as
an improvement, designed to increase the strength of the well known 4043, especially to provide higher strength fillet welds, while maintaining ease of welding, low melting temperature, good corrosion resistance, low shrinkage rate, high fluidity and low hot cracking sensitivity.
It is remarked that in all aluminum welding industry approximately 80% of the joints are fillet welds, and that the strength of fillet welds is directly controlled by the strength of filler metal.
The article reminds that the three filler metals 4043, 4047 and 4145 had been originally developed as brazing alloys, not to be diluted with base metals.
It had been observed that welds done with 4043 (Containing Silicon) on alloys of the 6xxx series (that include Mg) showed an increase in strength, depending on the amount of dilution of the base metal mixed in the weld metal, after postweld heat treatment and aging.
The improvement was
attributed to the formation of magnesium-silicide (Mg2Si), an effective strengthening precipitate.
The recent development took into account the lessons learned from the use of 4643 (the fifty years old consumable) to weld the 6xxx, that still required some dilution from the base metal, to show stregth increase after heat treatment.
However, as 4643 filler metal had reduced silicon (relative to 4043), hot cracking sensitivity was higher, fluidity was impaired, together with lower strength and fatigue life. Therefore only 90% of properties of 6061-T6 could be reached in the weld after postweld heat treatment and aging.
Thus the composition of 4943 was finely tuned to maintain the welding procedures used for 4043, to get the same corrosion resistance characteristics, low melting temperature, low shrinkage rate, high fluidity, low hot cracking propensity, low welding smut and discoloration, but to assure higher
strength after heat treatment. The Magnesium addition was established at 0.1-0.5% to avoid the crack sensitivity peak.
By comparing the fillet weld strength, the new alloy 4943 showed an increase of 20% relative to the same performed with 4043, with advantages in productivity, as less welding is needed for the same strength. And, relative to 4643, after heat treatment, it exceeds the properties of 6061-T6.
The favorable results were substantiated by thorough testing programs run on specimens welded with the new consumable. The tests permitted to select it for welding the sturdy 6061 aluminum frame that will support and lift the James Webb Space Telescope scheduled for launch in 2018.
See the Note now added to the Contact Us form.
James Webb Space Telescope
[NASA photo from the Welding Journal]
The article does not mention the appearance of the weld after anodizing. This is sometimes an additional selection criterion for filler metal, if the weld color after anodizing is requested to match that of the base metal.
In this case the weld grey color would stand out, similar to what happens when using 4043, due to the silicon content.
Interested readers are urged to seek the original article above for learning the whole story.
See the following Data Sheet on MAXAL 4943 at:
www.maxal.com/4943_datasheet.pdf
For further information see also:
Maxal Guide for Aluminum Welding (46 pages)
http://maxal.com/files/QuickSiteImages/Maxal_Guide_for_Aluminum_Wldg_9-12_doc.pdf
5 - Online Press: recent Welding related Articles
Exxon: Report Finds Outdated Welding Caused
Arkansas Pipeline Rupture
http://online.wsj.com/article/SB10001424127887323740804578599921900267376.html
Continuous Welded Pipes and Tubes - Global Strategic Business Report
http://www.sacbee.com/2013/07/09/5553700/continuous-welded-pipes-and-tubes.html
Barkley Plastics debuts in-mould internal welding
http://www.prw.com/subscriber/headlines2.html?cat=1&id=3139
Drawn arc stud welding advantages seen
http://www.maritimejournal.com/news101/vessel-build-and-maintenance/vessel-repair-and-maintenance/drawn-arc-stud-welding-advantages-seen
Successful commissioning of an SMS Siemag X-Pro® Laser Welder in South Korea
http://corecommunique.com/successful-commissioning-of-an-sms-siemag-x-pro-laser-welder-in-south-korea/
and also
X-PRO® LASER WELDER - Laser welding technology for strip processing lines (20 pages)
www.sms-siemag.com/pics/W7_318E_X-
PRO_Laser_welder_E.pdf
6 - Terms and Definitions Reminder
Oxide film is a work related discontinuity resulting from inadequate removal or use of insufficient shielding.
Powder blend is a mixture of two or more alloy metal or nonmetal powders prepared for further processing.
Random wound is spooled or coiled filler metal that is not wound in separate layers.
Self-shielded flux cored arc welding (FCAW-S) is a FCAW process variation where shielding gas is obtained only from combustion of the flux contained in the core.
Thermal expansion is the tendency of matter to change in volume as a consequence of a change in temperature.
Ultrasonic Wave Forms are modes of propagation of sound, used in ultrasonic examinations of metals: the modes are longitudinal, transverse and surface waveforms.
Vacuum Brazing is a nonstandard term for brazing processes taking place in enclosed containers below atmospheric pressure.
Water wash consists in forcing exhaust air and fumes through a water spray. As the contaminated air comes into contact with the water, water-soluble gases, vapors, aerosols, and particulates become dissolved. The trapped contaminants fall with the water and are discharged into a scrubbing liquor sump.
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7 - Article: Update on Inverter Technology
An article published on page 28 of the July 2013 issue of the Welding Journal explains the evolution of inverter technology for Gas Tungsten Arc Welding (GTAW) and outlines the progress made that now assures improved control with reliable equipment.
The article briefly reminds the origins of Alternating Current (AC) for GTAW and the discovery that the AC reverse polarity (electrode positive) half cycle contributed mightily to dissolve and remove tenacious oxides from the aluminum surface.
Superposed high frequency was needed to promote reignition. Failing that, the cleaning action was lost, the tip of the electrode tended to form a ball, broadening the arc, and magnetic distortion of sine wave ensued.
A great progress was the introduction of square wave in the seventies. However wave form imbalance was limited to a maximum of 75% DCEN (electrode negative) and 25% DCEP (electrode positive). Further reduction (down to 10%) of the DCEP percent time was needed to minimize electrode overheating, necessary to maintain a pointed end.
Note: Reminder:
See https://www.welding-advisers.com/Tig-welding-tips.html |
Such a progress could be achieved only with inverter technology, allowing frequencies over 200 Hz (Hertz = cycles per second), which permitted use of much lighter, portable, more energy efficient transformers.
Advanced tungsten electrodes are now suitable for both AC and DC. Price is more affordable, reliability is high, more welding programs can be stored, with repeatable weld quality and high productivity.
All the advantages of modern equipment point to the inescapable conclusion that Inverter Technology is the way to go. Readers are urged to seek the original article.
Those who did not yet embrace the inverter technology as applied to GTAW should probably think again and try it. They may not know what they give up.
In the process they may check also the advantages of Tip Tig. This commercial company (www.tiptigusa.com) advertises remarkable productivity advantages, probably worth to be checked in depth.
For further information you may wish to seek the following Selected Online References on Inverter Welding Technology, including Commercial Publications, that were grouped in a Mid Month Bulletin, reachable by clicking on Bulletin 88.
8 - Site Updating: Flood Welding (R), Forge Welding (R)
The Pages of this Month are, maybe, not in the mainstream of the most important welding processes. Nevertheless a complete overview of what is available should be part of the common knowledge of every welder.
The following pages were revised and updated. The first one, dealing with Flood Welding describes the process used to repair massive dies made of tool steels. It is a specialized discipline requiring vast experience and rigorous procedures. See the Flood Welding page in this website.
The other process, Forge Welding, reminds the origins of joining performed by blacksmiths probably from the origins of civilization. Now it is called a solid state process, and was performed as an art. The revised page is available by clicking on
Forge Welding.
To find pages covering other welding related argument, see the Site Map, or type your query in the Search window appearing in almost every page of this website.
Questions, comments and feedback are always welcomed.
Don't use Reply, use the Contact Us form instead.
Do you know...
(see Contact Us). (see 2 above) |
9 - Short Items
9.1 - Direct Chill Casting is a continuous method of making ingots for rolling or extrusion by pouring the metal into a short mold. The base of the mold is a platform that is gradually lowered while the metal solidifies, the frozen shell of metal acting as a retainer for the liquid metal below the wall of the mold. The ingot is usually cooled by the impingement of water directly on the mold or on the walls of the solid metal as it is lowered.
9.2 - Electrolytic Copper has been refined by electrodeposition, including cathodes that are the direct product of the refining operation, refinery shapes cast from melted cathodes, and products made therefrom.
9.3 - Guinier-Preston (G-P) zone is a small precipitation domain in a supersaturated metallic solid solution. A G-P zone has no well- defined crystalline structure of its own and contains an abnormally high concentration of solute atoms. The formation of G-P zones constitutes the first stage of precipitation and is usually accompanied by a change in properties of the solid solution in which they occur.
9.4 - Hot Corrosion is accelerated corrosion of metal surfaces resulting from the combined effect of oxidation and reactions with sulfur compounds and other contaminants, to form a molten salt on a metal surface that fluxes, destroys, or disrupts the normal protective oxide.
9.5 - Internal Shrinkage is the formation of voids within a casting, caused by inadequate feeding of that section during solidification.
9.6 - Morphology describes the characteristic shape, form, surface texture or contours of crystals, grains, or particles of a material, generally on a microscopic scale.
10 - Explorations: beyond the Welder
Space Launch System: Tooling Up to Build the World's Largest Rocket
NASA.
Curiosity Rover Samples Air for a Taste of Mars History
SA1.
Should Humans Eat Meat?
SA2.
Tornado Warning Times May Get Longer by Pinpointing Lightning Strikes
SA3.
An Olive Oil Compound That Makes Your Throat Itch May Prevent Alzheimer's
SA4.
11 - Contributions: A new Fusion Cladding Process
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The announcement of new processes does not happen frequently. When it arrives one should pay attention and take note. During the development years, before anyone heard of it, the new process was tested and demonstrated to perform successfully the tasks involved.
What may still be lacking, at first, is thorough understanding of economical advantages relative to competing processes. This may be critical to success. Therefore if it determined that significant benefits could potentially be achieved, it may be worth to study in depth productivity and costs to substantiate momentous decisions.
As corrosion damages are valued in trillions of dollars per year, globally, any gains obtained by implementing effective prevention measures may be extremely valuable.
A recent article1, published at page 17 on the July 2013 issue of Advanced Materials & Processes (AM&P), an ASM International magazine, introduces the efforts of a commercial company, to provide practical equipment capable of performing, with a new process, cladding of corrosion resistant materials on surfaces of steel implements.
Among other solutions, a unique piece of equipment was realized to perform cladding on the internal surfaces of pipes. The heart of the system is a special quartz plasma lamp, researched and developed by ORNL (Oak Ridge National Laboratory). The article does not provide many details on the lamp. These are given in other publications.
The Vortek lamp2, a high intensity arc lamp, radiates high-energy-density infrared light. Its power ranges from 350 to 3500 W/cm2, with total power output from 150 kW to 1 MW. The thermal source of the plasma arc reaches a temperature of 10,000K (17,500°F).
Roughly 80% of its energy is emitted in the infrared spectrum. This non coherent light source is highly efficient for rapidly heating metal and oxide surfaces at exceptionally elevated rates (degrees per second).
Due to the special characteristics of heat flux transfer, weld dilution is greatly reduced, relative to traditional laser and weld overlay processes, enabling more control over thickness microstructures.
Additional applications of the technology are introduced in a publication3 providing an overview of developments in various stages of deployment.
The AM&P article goes on explaining coating rates achieved in terms of coverage (area per hour) and deposition rates (weight per hour). Several protective materials against corrosion, wear and heat effects were tested and new types are under development.
The results seem promising. As often happens with new processes, only experience will show the specific niches where applications are particularly favorable in terms of protection achieved against reduced costs involved and shorter work times.
Interested readers are urged to explore the following downloadable publications to get a more thorough understanding of this important development.
1Fusion Cladding Prevents Pipeline Wear and Corrosion (5 pages)
ASM.
2Materials Processing Using ORNL's Powerful Lamp
Sorry! The link was removed by the source
http://web.ornl.gov/info/ornlreview/.
3The use of High Density Infrared (HDI)
Heating
for Surface Modification/Coatings Processes (11 pages)
AMA.
12 - Testimonials
Date: 27 Jun 2013, 10:31:00 AM
Subject: Submission from
On 01 Jul 2013, 03:31:17 PM, the following results were submitted from the
"Form 5" on welding-advisers.com:
Name: Jack Simpson
Country: Canada
Organization: I.A.M.
Your Task: welding
Elia
Thanks for your response. [...]
Thanks for your help
Jack Simpson
Name: William Chapman
To: Welding Advisers
Date: 03 Jul 2013, 02:11:36 PM
Subject: super duplex
Thanks very much for the requested information, perfect.
Regards,
Bill Chapman
13 - Correspondence: a few Comments
13.1 - I proposed above (Section 3) to expand somewhat on my painful experiences.
I should put forward that I like giving useful advice.
Especially if I can help, if someone (the interested person) takes note, and if my effort is acknowledged.
However, to be able to help, I need to be informed. I need to understand the problem and the limiting factors.
Occasionally the problem should be kept from public eyes, mostly for commercial reasons connected to competition.
I know to keep secrets. I can assure inquirers that details, drawings or procedures are treated
accordingly.
To those who are in doubt I can only say: if you don't trust me don't ask me.
If you don't want to tell me all the details of your case I cannot help you.
The case exposed above (Section 3) was painful because the inquirer seemed not to understand my need to know. He thought that he had acted reasonably by putting together preconditions (already committed, machined parts) and requesting a solution (a viable welding process? Pre and post heat? type of weld?).
Instead of trying to explain, to look for a solution, he left without a word.
13.2 - The rare few who thank me for my efforts to provide useful answers make my day.
14 - Bulletin Board
14.1 - Int’l Conf. on Solar Energy Materials and Energy Engineering
Sept. 1, 2. Hong Kong.
www.semme-conf.org.
14.2 - GAWDA Annual Convention
September 15-18 - Orlando,
Fla.
www.gawda.org
14.3 - ASM Heat Treating Society Conf. and Expo.
Sept. 16–18. Indiana Convention Center, Indianapolis, Ind.
www.asminternational.org/content/Events/heattreat/
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