Fisheye Defect

Date 09-10-2008 12:54

To me the description sounds like when you finish your weld and you do not fill enough. You end up with a small depression and a slight round hole (fisheye).

By Lawrence (*****)

Date 09-10-2008 15:36

AWS A3.0 Standard Welding Terms and Definitions says:

Fisheye
A discontinuity, attributed to the presence of hydrogen in the weld, observed on the fracture surface of a weld in steel ahat consists of a small pore or inclusion surrounded by an approximatly round, bright area.

Don't have a picture...

Sorry.

By Stephan (***)

Date 09-10-2008 19:55

Lar,

please allow me to attach an appropriate picture to your explanation.

Hope this helps...

Best regards,
Stephan

By CWI555

Date 09-11-2008 17:58

Good reference there Stephan.

In the south this is a fisheye (sorry couldn't resist)

By jwright650 (*****)

Date 09-11-2008 18:22

And here is one of our forum members looking a fish in the eye....LOL

By jrw159

Date 09-11-2008 20:41

Something smells fishy!!

jrw159

By Stephan (***)

Date 09-12-2008 01:15

John,

let me guess.

This was before the specimen's tensile test? :-)

Great picture! Now I'm sure that David is perfectly happy!

Best to you,
Stephan

By michael kniolek (***)

Date 09-12-2008 01:09

Funny man.....but i thought thats called a walleye?
MDK

By jrw159

Date 09-12-2008 15:32 Edited 09-12-2008 15:37

Michael,
That is actually a northern pike. :-)

Attached are pic's of both species. The one on the left is walleye, and the other is northern pike.

IMHO walleye is the better tasting fish.

jrw159

By Lawrence (*****)

Date 09-12-2008 16:40

Walleye is the best tasting fish I've ever had\

Closely followed by sushi carved from a tuna still flopping on the deck while 50 miles out from Half Moon Bay!

To be honest I've never eaten a Northern... All catch and release.

By jrw159

Date 09-12-2008 17:02

I have not had the privledge of tuna as fresh as that. This is something I would love to try. I seem to recall something about the still beating heart being quite an experiance as well. :-)

jrw159

By Stephan (***)

Date 09-12-2008 01:10

Gerald,

if I would have been the lucky one who would have had this "sample" I wouldn't have resisted as well! :-):-):-)

Best to you!
Stephan

By jwright650 (*****)

Date 09-12-2008 11:55

Lawrence,
Since you didn't have a picture....look below. Can you guess who that angler is?

To the original poster, I hope we didn't ruin your thread for you, just having some fun with Lawrence.

By Lawrence (*****)

Date 09-12-2008 15:21

That is one fine Northern isn't it!

By jwright650 (*****)

Date 09-12-2008 15:44

The angler or the fish?

By Stephan (***)

Date 09-12-2008 18:12

John,

"...I hope we didn't ruin your thread for you..."

with regard to even your statement, please let me add two more words on this interesting topic a bit more "seriously" (even though the biology of the Northern American fish species is fairly interesting as well).

The origination of fisheyes is quite interesting due to it is that specific.

Normally one can't determine the hydrogen being responsible for even the "fisheye appearance" until the deformation or the fracture has occurred. Thus one might ask: "Where is the fisheye appearance originated actually?". As one can see in the jpeg I had attached three days ago, there is a difference with the fracture appearance between the "plain" fracture surface (rather coarse), see again the attached and "modified" picture, and the adjacent area around the "crack initiators".

While the cracking was initiated from even those "darkened" areas (quasi the pupil of the fisheye) which were pores from a cold lap (Area "A" in the picture) the hydrogen which was absorbed atomically prior to cracking is being actually "pumped" proportionally with the movement of dislocations along the {110} gliding planes. Finally the whole action results in an accumulation of dislocations saturated with molecular hydrogen. The fracture of those hydrogen saturated areas is even more "fine grained" and thus different to those areas which are showing a "regular" fracture surface appearance.

This however, just as a short addendum...

Best regards,
Stephan

By david.crawford (*)

Date 09-14-2008 05:18

Thank you, that is exactly what I've been trying to find. Also to everyone else, even thought pictures of fish were off topic, it was still nice for a laugh. :)

By swsweld (****)

Date 09-10-2008 16:59

David, I looked in vain last night for a picture of a fisheye.
I agree with the previous descriptions.
From a welders view the fisheye is when you are tig welding and you pull your tungsten out to terminate the arc. It leaves a divot (shaped like a fisheye) if not done correctly.

By Kix

Date 09-12-2008 13:23

Check out this thread, it has very informative information on it about hydrogen porosity and how to fix it. I even have a few pictures of fish eyes/hydrogen porosity in a couple of my tensile pull pictures in this thread. Hope this helps!! http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=96382;hl=aluminum%20porosity

By swsweld (****)

Date 09-21-2008 01:35

I found these at Fish eyes R us.com

[IMG]http://i304.photobucket.com/albums/nn196/swsweld/9-19-083rdBrigade049.jpg[/IMG]
[IMG]http://i304.photobucket.com/albums/nn196/swsweld/9-19-083rdBrigade050.jpg[/IMG]
[IMG]http://i304.photobucket.com/albums/nn196/swsweld/002-1.jpg[/IMG]
[IMG]http://i304.photobucket.com/albums/nn196/swsweld/007.jpg[/IMG]

By CECW7611 Date 10-03-2008 01:32 Edited 10-13-2008 13:41

A fisheye is a recognition that hydrogen will exist in welds made using cellulosic coated electrodes because they are designed to weld with a small moisture content. The hydrogen will diffuse into the molten weld metal during welding. During nick break testing, depending on how the load is applied, this hydrogen will migrate along grain boundaries and collect just before the specimen breaks. The appearance of the indication is usually circular and grainey, grey with typically a black or darker dot in the center of it, basically centered the circular area. Almost exactly like a fisheye, thus the name. This indication is allowed in the API 1104 Standard. But sometimes, to the inexperienced, the round nature of this indication is interpreted as porosity and the nick break would fail due to misinterpretation. Sometimes, there may be several fisheyes in one nickbreak depending on the thickness of the material.

Several years ago Lincoln Welding did have an excellent bulletin concerning fisheyes and had an excellent picture. I don't know if this is still available though.

I did look at the photos above and they really indicate shrinkage in the weld puddle, the puddle cooling from the outside toward the middle. This may appear as a crater crack if left in the root bead and radiographed (again API 1104). Sometimes it may also be interpreted as hollow bead or linear porosity.