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PWL#082 & 082B - Do you open it? 13.3 -Superplasticity, Borescopes, Handling Fillers - Weldability
June 01, 2010
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PWL#082 - Superplasticity and Superplastic Forming, Borescopes, Handling Filler Metals on Construction Sites, Microhardness Testing, Metallurgical Expertise, Electrogas Welding, Biocompatible Materials and more...

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June 2010 - Practical Welding Letter - Issue No. 82


Mid June Bulletin

Please be advised that the Mid Month Bulletin is now integrated with the regular PWL publication. You will find it further down, past the end of PracticaL Welding Letter. Don't miss it!

Important Announcement

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a rich collection of valuable information from expert Internet Sources, on
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and Metals Welding, Volume 2.
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1 - Introduction

2 - Article - Superplasticity

3 - How to do it well: Inside tube inspection

4 - How to Keep Filler Metal on the Job Site

5 - Online Press: recent Welding related Articles

6 - Terms and Definitions Reminder

7 - Article - Microhardness test

8 - Site Updating: Metallurgical Expertise, Electrogas Welding

9 - Short Items

10 - Explorations: beyond the Welder

11 - Contributions: Biocompatible Materials

12 - Testimonials

13 - Correspondence: a few Comments

14 - Bulletin Board

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1 - Introduction

Hello everybody! As advised in the last Mid Month Bulletin, this issue 82 of Practical Welding Letter for June 2010 includes also the Mid June Bulletin which is released hereafter. Please make sure you scroll down, past the end of the regular PWL, to see it.

This 82nd issue opens with a short introduction on Superplasticity, a particular property of certain fine grained metals, that permits superplastic forming to an extent impossible otherwise. Although used for somewhat special applications, its usefulness is out of doubt.

Then a short review is offered of the Borescope, optical devices used for performing visual inspection of enclosures without direct line of sight to the interested areas.

A reminder is given of the need to observe strict storing practices for consumable filler metals, with even more attention and care when working in construction sites where conditions may be more difficult. Otherwise, besides the loss of good and expensive material, one risks also to endanger the construction integrity.

A short note follows on microhardness and on how it is different from regular hardness testing. The results must be correctly reported and interpreted in their context, to be of use in understanding the real conditions of the tested specimen.

A presentation of the new pages of the Month (added to the Website) is given, the first on Metallurgical Expertise, the fundamental knowledge invaluable when researching welding production mishaps.

The second page reports on a process, Electrogas Welding, that has remarkable economic success when employed where it is most useful. Although somewhat specialized, in was introduced in wide different industries for its intrinsic advantages.

The last article gives a glimpse on Biocompatible Materials, those used for medical devices implanted in the human body. Apart from their scientific interest, studied by teams including expert professionals from widely separated disciplines, a remarkable market liveliness with huge revenues is forecast due to continuous improvements and new applications, realized to meet urgent needs.

The other departments can be found at their usual location. Keep updated by browsing through all the sections, and don't forget to look for the Mid Month Bulletin, now appended at the end of the regular PWL edition, because of distribution difficulties.

Your comments and feedback are welcome. DON'T USE REPLY to send us your messages! Use Contact Us instead. And even more welcome would be your diffusion of the word and message of this website, and of the information here available, to your friends, correspondents and colleagues. Forward them this page and the pages you like. Ask them to subscribe to this periodic newsletter so they can get the bonus book on Hardness Testing made Simple. Thank you.

2 - Article - Superplasticity

Did you ever heard of Superplasticity?

A short note on this subject was published (9.3) in Issue 67 of Practical Welding Letter for March 2009. Click on PWL#067 to see it.

Superplasticity is a particular state where it becomes possible to deform crystalline solid materials in tension to unusually large plastic strains. Such a state is usually achieved at high temperature, typically half the absolute melting point and for extremely slow deformation processes.

Half the absolute melting point temperature means a temperature equal to the half of the melting temperature expressed in degrees Kelvin. That is equal to the temperature expressed in degrees Centigrade or Celsius + 273.15 (0K = 0C + 273.15).

Superplastically deformed materials get thinner in a very uniform manner, rather than forming a local narrowing which leads to fracture.

Superplasticity is possible in metals and ceramics with fine grain size and a fine dispersion of thermally stable particles which maintain the fine grain structure (that is, inhibit grain growth) at the high temperatures required for superplastic deformation.

Superplastic forming permits the production of parts with complex contour in a single press cycle, providing significant economic advantages. The finished products have excellent precision and fine surface finish.

The major drawback is the very low rate of deformation that extends the process for long times relative to normal stamping operations. The second disadvantage is the need to heat and keep at high temperature the material and the tools for as long as the process requires.

Typical superplastic formed materials are aluminum base alloys heated at 450–520 0C (840-970 0F) and titanium base alloys at about 900 0C (1,650 0F).

According to a recent note published in ASM AM&P, May 2010, page 29, "SPF [...] in recent years has emerged as a suitable process for high volume automobile manufacturing. Superplasticity in general is gaining interest in many manufacturing segments and is being transformed from a low-volume and prototyping process into mainstream production. Many companies have recently added SPF as a capability".

Note: To find this (and all other articles) online, type "ASM AM&P" in the search window of a search engine and enter. Click on "Online access...", select the May 2010 Issue, select the "Optimizing..." item and download the article.

On this subject see also:

Superplasticity (16 slides presentation)

Superplasticity and Forming of Advanced Materials (6 pages)

3 - How to do it well: Inside tube inspection

Q: How can I perform visual inspection of welds or corrosion condition from the inside of tubes or small containers with no direct line-of-sight access?

A: You should procure long and thin optical instruments called Borescopes. There are many types, portable, rigid or flexible if made with optical fibers, and they contain an autonomous light source to illuminate the area to be inspected. Sophisticate equipment may include a camera and transmit the view to a portable TV screen.

There use is invaluable but the inspector needs to get training and some experience before being able to perform reliable inspections.

Interested readers can browse manufacturers' catalogs to find the instrument best adapted to their requirements.

4 - How to Keep Filler Metal on the Job Site

Incorrect handling of filler metal consumables is not only a waste of precious assets, it may endanger the integrity of welded constructions if used without proper controls. It is therefore important to be reminded of basic storing requirements to be observed even when out on the construction site.

A recent article on this subject provides useful tips likely to be welcome by those who work on job sites and face problems of proper handling of filler metals.

It can be found at:

5 - Online Press: recent Welding related Articles

Modeling transport phenomena in welding processes

Intelligent Robotic Arc Sensing – A Comparison of Available Technologies

New TIG Technology: The Right Choice

Improving productivity with submerged arc welding

Bonding with adhesives

6 - Terms and Definitions Reminder

Neutral Flux used in submerged arc welding, produces a weld metal composition independent of the welding parameters, especially voltage.

Orifice Gas surrounds the electrode in a plasma arc torch or plasma spraying torch, becomes ionized as it flows through the arc, and exits from the constricting nozzle as a plasma jet.

Preflow Time is the time interval elapsing between the start of shielding gas flow and arc initiation.

Surface Roughening is a group of methods used for producing irregularities on a surface in view of providing or improving mechanical adhesion and interlocking as a preparation for depositing layers of sprayed deposits by thermal spraying.

Tungsten Electrode is a non consumable electrode made of tungsten used in arc welding, arc cutting and plasma spraying.

Unmixed Zone is a thin boundary layer of weld metal adjacent to the weld interface, that solidified without mixing with the remaining weld metal.

Visual Standards are surface conditions requirements agreed upon or established by a binding document including limits of acceptable discontinuities and visual appearance of the completed weld.

Weldment is any assembly whose component parts are joined by welding.

7 - Article - Microhardness test

The Microhardness test or the micro indentation hardness test is employed whenever the use of any of the regular hardness tests cannot be performed. This happens when the thickness of the part is very thin (a razor blade or a foil) or when one wants to find the local hardness of very limited areas, like those of individual grains or of definite constituents visible in metallographic sections.

Also for measuring the rapidly changing hardness gradient, (within a few tens of a millimeter) along the thickness of a sectioned specimen, due to surface hardening processes such as carburization.

One popular test is performed with the same diamond pyramidal indenter used for Vickers hardness testing, except that here the loads are very low. The measure of the two equal diagonals permits the calculation of the microhardness or the lookup in suitable tables.

In another popular test, called Knoop, the pyramidal elongated diamond indenter leaves an oblong impression where the two different diagonals are measured precisely under a microscope.

The local values determined depend much on the loads used and are not representative of bulk properties, therefore extrapolation to other mechanical properties is not possible.

These tests are to be performed according to an approved Standard as follows:

ASTM E384-10e2
Standard Test Method for Knoop and Vickers Hardness of Materials
ASTM International / 01-Feb-2010 / 42 pages
Click to Order.

BS EN ISO 6507-1:2005
Metallic materials. Vickers hardness test. Test method
British Standard / European Standard / International Organization for Standardization / 23-Jan-2006 / 30 pages
Click to Order.

BS EN ISO 4545-1:2005
Metallic materials. Knoop hardness test. Test method
British Standard / European Standard / International Organization for Standardization / 30-Jan-2006 / 26 pages
Click to Order.

8 - Site Updating: Metallurgical Expertise, Electrogas Welding

The Pages of this Month deal with different subjects that could be of interest to some of the readers. Metallurgy plays an important part in the success of any welding operation. When something goes wrong the basic metallurgical factors must be checked once more, to find out which change is responsible for the failure.

Metallurgical know how should be available at least when needed. Suitable arrangements should be prepared in time, to be able to summon instant help in case of necessity to limit the disturbance in production to the minimum.

To see this new page click on Metallurgical Expertise

The other Page of this Month describes Electrogas Welding, which is a combination of the lessons learned from two known processes: Gas Metal Arc Welding (GMAW or Mig) and Electroslag Welding (ESW).

It is true that the application requires a few preliminary conditions. First thickness from 12 to 75 mm (0.5 to 3 in.) and then the possibility to have the joint stand vertically, for welding from bottom to top.

But if these conditions are met then the said process is probably the most economic that can be employed for realizing successfully such joints. See the new page by clicking on Electrogas Welding.

Keep updated by subscribing to the RSS (follow instructions under the NavBar in each page), look at the Site Map, or see periodically the Welding Blog.

Let us have your comments, feedback or questions by using the form available at Contact Us. Inform your friends of this website: they too may benefit of the quite extensive information available here.

9 - Short Items

9.1 - Fluidized Bed is a contained mass of a finely divided solid that behaves like a fluid when brought into suspension in a moving gas or liquid. Used for furnaces.

9.2 - Galling is a condition generated by local welding and spalling and further roughening of rubbing surfaces. Also a severe form of scuffing associated with gross damage to the surfaces or failure.

9.3 - Hearth is the bottom portions of certain furnaces used for melting and refining, that support the charge and sometimes collect and hold molten metal.

9.4 - Impingement is a continuing succession of impacts between liquid or solid particles and a solid surface for modifying its properties.

9.5 - Linear Elastic Fracture Mechanics is a method of fracture analysis that can determine the stress (or load) required to induce fracture instability in a structure containing a cracklike flaw of known size and shape.

9.6 - Photomacrograph is a photographic representation of the surface of a prepared specimen at a magnification not exceeding 25×.

10 - Explorations: beyond the Welder

NASA to Launch Human-Like Robot to Join Space Station Crew

Fake Botox, Real Threat

The Nature of Time (9 pages)

'Tiny Forests' Yielding Rich Nanotube Harvests (video)

The Doctor Is Out, but Robotics Technology Is In

11 - Contributions: Biocompatible Materials

Biocompatible Materials have demonstrated capability to exist and perform in medical devices implanted in living organisms without rejection and without allergic or toxic adverse reaction, without destroying enzymes cells or tissue, or causing thrombosis and tumors.

Biomaterials research is a very active field of interest, requiring close cooperation among researchers from many disciplines, including physics, chemistry, biology and engineering.

Some common implants include, among other applications, hip joint replacements, artificial heart valves, dental prosthesis and contact lenses.

The forecast of demand for biocompatible materials will increase remarkably in the next few years. Stricter FDA approval requirements and production standards demand upgrading of materials used in medical and dental implants and drug delivery systems.

Besides increasing inroads of different types of plastic materials, specialty metals like titanium alloys, nitinol, cobalt alloys and ceramics will continue to be used consistently in specialty devices and equipment such as orthopedic and dental implants, stents, pacemaker and defibrillator components.

Note that stainless steel, once the material of choice, is considered presently a metal of low biocompatibility.

Rapid prototyping techniques are increasingly being used to shorten the time between design and testing of elaborate devices.

Note: Interested readers can follow each month news relative to Medical Materials by searching the current issue of AM&P, as explained above in the Note of section 2.

See on this subject:

Biocompatible Materials (19 pages)

12 - Testimonials

Name: Gregorius Oswandi
E-mail Address: removed for security
Country: Indonesia
Introduce Your Organization: Pressure Vessel fabricator
Describe Your Responsibility: Engineering and manufacturing

Dear Mr. Levi
Now I feel more confidence answering my boss question about these weld defects.
Thank you very much.
Thank you for providing time for me.
Best regards,

What a surprise, I have your reply very quickly. Is there no lag of time between your place and Indonesia?

E-mail Address: removed for security
Country: United States
Introduce Your Organization: R. G. SMITH COMPANY
Describe Your Responsibility: PURCHASING MANAGER

I appreciate your response. I think we are covered.
Thank You,

13 - Correspondence: a few Comments

13.1 - I love receiving questions from interested readers. The more complete the exposition of the problem the better the chance to receive a meaningful answer.

Not all inquirers seem to understand this simple rule. I am amazed at finding messages devoid of content: what am I supposed to do with them? Although against my own rules, sometimes I don't answer at all. Why should I? No question, no answer.

13.2 - I don't like queries in the most general terms like the following:
"We need to buy some welding and thermal spray machines, pls give some quotation and more info"
Apart from the fact that my website provides only good information, not hardware, whould you think this a legitimate way to ask for data?

What Process? Which Range? The amazing thing is that the inquirer seems to be an equipment supplier. Would he be able to provide quotes for "some welding machines"?
I did not answer to this non serious correspondent.

13.3 - Do you open this newsletter? I found recently that the majority of the subscribers to this letter do not even open it up. As it is now, I suspect, it does not satisfy sufficiently the curiosity or the needs of most subscribers.

Therefore may I ask those who do read it more or less regularly, how to entice a larger number of those who receive it to read and find some useful bits of information?

Is it the content? Is it the format? Are there other subjects to be added? Any ideas? What do you think?

Let me know your suggestions by indicating "newsletter" in the subject. I appreciate your opinion. Please use the form at Contact Us.

14 - Bulletin Board

14.1 - MACH 2010 - The market-leading manufacturing technologies show in the UK
7 - 11 June 2010. NEC, Birmingham, UK

14.2 - 2nd Canadian Cold Spray Conference
June 15-16, 2010, Industrial Materials Institute of
the National Research Council of Canada,
Boucherville (Montreal), QC, Canada

14.3 - 63rd Annual Assembly and In'l Conf. of the
International Institute of Welding (IIW)
July 11-17, 2010, Swissotel The Bosphorus, Istanbul, Turkey

14.4 - Take the SBI Video Tour
Your Mini-Course In Online Marketing
Click on the Video Tour!

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Please continue to browse hereafter for the Mid June Bulletin.

Copyright (©) 2010, by Elia E. Levi and
All Rights Reserved

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keywords: Weldability Testing, Varestraint, Gleeble, Sigmajig test, Implant Test

Bulletin 50
June, 2010

PWL#082B - Resources on Weldability Testing, Varestraint, Gleeble Simulations, Sigmajig test, Implant Test, Equivalent Carbon Content, Welding Process Effects, Improving Weldability, Acoustic Emission, Aluminum Alloys, Steel, Carbon Steel, HSLA, Stainless Steel, High Performance Steel, Nickel Alloys and more...

Mid June Bulletin

June 2010 - Resources on Weldability Testing - Bulletin 50

Important Announcement

For assembling at no cost your own Encyclopedia Online,
a rich collection of valuable information from expert Internet Sources, on
Materials, Volume 1,
and Metals Welding, Volume 2.
Still for a Short Time Only

Get Both Now at 20% Discount!

Order Now!.


The Mid Month Bulletin is now integrated with and follows the regular PWL publication.

The subject of this Bulletin was thoroughly dealt with in this Welding Advisers website.

Click on the link to reach the page of my website dedicated to Weldability Testing.

By searching "Weldability" with Google from within this website one gets more than 150 results (there may be some repetitions) readily appearing upon clicking on the links.

A short note on the Varestraint Test was published (9.6) in Issue 14 of Practical Welding Letter for October 2004. Click on PWL#014 to see it.

A short note on the Gleeble Testing was published (9.4) in Issue 15 of Practical Welding Letter for November 2004. Click on PWL#015 to see it.

An Article on Weldability Testing for Weld Repair was published (2) on Issue 27 of Practical Welding Letter for November 2005. Click on PWL#027 to read it.

The Definition of Weldability was published (6) in Issue 35 of Practical Welding Letter for July 2006. Click on PWL#035 to see it.

A short note on the Sigmajig Test was published (9.4) on Issue 39 of Practical Welding Letter for November 2006. Click on PWL#039 to see it.

An Article on Gleeble Simulations was published (2) in Issue 79 of Practical Welding Letter for March 2010. Click on PWL#079 to see it.

[Note: DON'T USE REPLY to send us your messages!
Use Contact Us instead.]

Previous Issues of Practical Welding Letter are available at the Index of Past Issues of PWL, while the Titles of important Articles published there are in the page on Welding Topics.

The Index of all previous Issues of the Mid Month Bulletins can be found in the page of Welding Resources.

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
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 selected them 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.

* * *



Equivalent carbon content

What is 'Weldability'?

TALAT Lecture 4202: Weldability of Aluminum

Weldability of materials - Cast irons

Materials and Weldability (24 frames)

Component Weldability Test (2 pages)

Weldability Testing of Structural Steels: Implant Test

Welding Process Effects in Weldability Testing of Steels (8 pages)

Weldability Testing of Laser Welded Stainless Steels (9 pages)

Weldability of Ni-Co-Cr-Si Superalloy: HR-160 alloy (10 pages)

Weldabiliy of High Performance Steels (16 pages)

Weldability and Corrosion Studies of AISI 316L Electropolished Tubing (11 pages)

How to Test the Weldability of Various Plastics

The role of Aluminum on the Weldability and Sulfidation Behavior of Iron Aluminum Cladding (8 pages)

Bead-on-plate Weldability of Al-5052 alloy using a Disk Laser
(4 pages)

Weldability of Li-bearing aluminum alloys (21 pages)

Techniques for improving the Weldability of TRIP Steel using Resistance Spot Welding (13 pages}

Resistance Spot Weldability of Low Carbon and HSLA Steels
(11 pages)

Resistance Spot Weldability of High Strength Steel (HSS) Sheets for Automobiles (7 pages)

Weldability of Nickel Alloys 600 and 690 (4 pages)

Effect of Welding Parameters on the Weldability of Material (5 pages)

Development of Weldable Martensitic Stainless Steel Line Pipe by HF-ERW process (10 pages)

Use of Acoustic Emission to understand a Weldability Test (3 pages)

High Strength Steel Weldability DOE Test Method Correlation
Welding Task Force

December 2, 1998

Reference Documents for Purchase

Weldability Test for Weld Filler Metal Wire
SAE International / 01-Feb-2002 / Click to Order.

BS EN ISO 18278-1:2004
Resistance welding. Weldability. Assessment of weldability for resistance spot, seam and projection welding of metallic materials
British Standard / European Standard / International Organization for Standardization /
25-Nov-2004 / 14 pages
Click to Order.

BS EN ISO 18278-2:2004
Resistance welding. Weldability. Alternative procedures for the assessment of steel sheets for spot welding
British Standard / European Standard / International Organization for Standardization / 24-Nov-2004 / 28 pages
Click to Order.

DIN EN ISO 14327
Resistance welding - Procedures for determining the weldability lobe for resistance spot, projection and seam welding
(ISO 14327:2004); German version EN ISO 14327:2004
Click to Order.

Books for purchase

John C. Lippold and Damian J. Kotecki
Welding Metallurgy and Weldability of Stainless Steels

S. Liu and J.E. Indacochea
Weldability of Steels

* * *

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