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Up Topic Welding Industry / Technical Discussions / Depth of Penetration
- - By simons (*) Date 02-22-2006 14:22
Can Someone please clarify for me. We are performing fillet welds on automotive components. The Standard (ANSI/AWS D8.8-97)states: "The effective weld size shall be equal to or exceed 90% of the thickness of the thinner material being joined". and, "The joint penetraion shall extend to the joint root".
Does this imply that "depth of fusion" is irrelevent, provided the weld size is FUSED continuously to the root?
Parent - By 803056 (*****) Date 02-22-2006 15:38
Terminology is the problem.

The fillet weld is deposited on the joint, whereas the groove weld is deposited in the joint.

The depth of fusion is measured normal to the fusion face, where as the joint penetration is equal to the weld size for a groove weld and is measured from the surface of the joint to the weld root.

The fillet weld needs to have fusion to the joint root, i.e., the corner of the joint where the two members meet, but not necessarily beyond. There is no requirement that the fillet weld extend into the joint, i.e., beyond the point where the two members intersect.

I hope this helps. If not, refer to AWS A3.0 Standard Terms and Definitions. Be sure to look at the latest revision.

Send me an e-mail and I'll send you a sketch of the terms.

Best regards - Al
Parent - - By H.Dibben (*) Date 02-22-2006 17:21
I would assume the effective weld size means the size of the throat on a fillet weld. The throat size is 0.7 times the weld size, which means to have an effective weld size of 0.9 times the material thickness, the fillet weld must be larger than the material thickness.

I am not familiar with AWS D8.8, so I may be misintreping something.
Parent - - By simons (*) Date 02-22-2006 18:08
Effective throat is measured from toe-to-toe, perpendicular to the root. I'm pretty clear on this. My question is " depth of penetration and fused leg.
Parent - - By chall (***) Date 02-22-2006 18:33
Effective throat is the shortest distance measured from root to face; with the theoretical face being a straight line from toe to toe.

Parent - By Lawrence (*****) Date 02-22-2006 18:40
Charles is correct in his discription of throat.

The weld size in the presented senerio, I think will be an isosceles triangle composed of the the minimum leg length which is the thickness of the thinner member, on each leg and to the root.
Parent - - By simons (*) Date 02-22-2006 18:50
Thanks for the reply and you are correct. But my question isn't Throat though, It's "depth of penetration". We are performing fillet welds on automotive components. The Standard (ANSI/AWS D8.8-97) states: "The effective weld size shall be equal to or exceed .9t of the thickness of the thinner material being joined"; And, "The joint penetration shall extend to the joint root". does this imply that "depth of fusion" (along the "fused leg") is irrelevant, provided the weld size (legs) are "FUSED" continuously to the root?
I have looked through ANSI/AWS D8.8-97 and several other independent standards (FMC, DMX, Mazda,Mercedes) and none of them address depth of fusion for fillet welds on automotive components, only fused leg & throat. Am I correct in assuming that depth of penetration is irrelevant provided the Fused Leg(s) & Throat meet the requirements? Or is depth of penetration left to be determined through testing on a "per application" basis.

Let me know your opinions.
Parent - - By QCCWI (***) Date 02-22-2006 20:05
"The joint penetration shall extent to the root" that means you must have penetration at the root. The depth of penetration does not matter as long as you have some penetration.

If you have 2 plates at 90 degrees you will have joint penetration at the root unless the welding machine is set wrong or the welder is holding the rod/gun at an angle that would allow slag to flow under the weld and the slag gets trapped under the weld at the root. These things will cause you to have lack of penetration at the root.

If you have 2 plates on a slope that would make the corner where the 2 plates meet smaller than the rod/wire size that you are using would also cause you to have lack of penetration at the root. I do believe D1.1 calls this "z" loss or you can call it the point were root penetration is impossible do to the fact the rod/wire would arc before it made it to the root. For example (this is a guesstimation)if you have a plate laying over on a 60 degree slope the point where the root is located would be way less than 1/16" so you could not get root penetration with 1/16" wire. D1.1 would want the weld to be larger than required to account for the "z" loss.

AWS D1.1 says penetration shall extend to the root but not necessarily beyond.
Your Standard states penetration shall extend to the root. If the penetration is only 1/64" you are ok.If you have root penetration of .01 of an inch you are ok. If the weld has no penetration at the root the weld is not up to standard.
Parent - - By simons (*) Date 02-22-2006 20:54
Ok. If I have two plates at 90+/- degrees. The thinest plate is .250 inch. The Standard for fillet welds say's ".9t or greater for fused leg (t=thinest member welded), .6t minimum throat.
So, I would be required to to have (2) fused legs (one leg on each plate) at .230 inch min. and a actual throat of .150 inch min. The Fused Leg(s) would measure frome the toe(s) to the intersection of the two plates. And the Throat, from the Face of the weld to the intersection of the two plates, Correct?
If this is true how deep does the penetration (into the plates) have to be, along the fused leg(s)? I understand that the penetration does not have to go beyond the root of joint, only too the root of joint, but is there something that dictates how deep the penetration has to be along the fused legs, or does it just need to be fused.
I know this may sound confusing, which I think is part of my dilema!

Parent - By QCCWI (***) Date 02-22-2006 21:41
The penetration only has to extent to the root. How much past is not an issue as long as it makes it to the root.
Parent - - By CHGuilford (****) Date 02-22-2006 23:23
You are basically correct. Theoretical throat, as was stated already, is the shortest distance from the theoretical leg intersection (root) to the hypotenuse of the triangle that represents the weld size that is desired. Actual or effective throat takes into account the amount of weld penetration achieved and is the shortest distance when measuring from the depth or penetration of the root to the actual weld face.

Now that I have added confusion to this, I suggest that you see what those differences are in AWS 3.0-2001 and in other AWS publications. The picture truly is worth a thousand words. If you can't find a copy let me know and I can email a sketch to you.

There is no requirement for minimum penetration along the fillet legs. The weld metal simply has to be thoroughly fused to the base metal along the joint.

In actual practice you will (or should) find there is some penetration past the fillet "walls" and past the root. That is, when looking at the triangular cross section, the weld will have melted outside the triangle along the 2 sides, and be just at or outside of the intersection of the 2 sides (root).

But if there were some way to control the weld so the penetration of fusion occurs only at the surface of the walls, that would be all that is needed.

Parent - - By Lawrence (*****) Date 02-23-2006 00:21

There is a bit of unclear wording.

The code calls for a specific root fusion (as mentioned above)

High speed robotic lines often in the auto industry will perform random sectioning of production units and a macro etch will require a depth of penetration revealed by the etch to be 90% of the thickness of the thinner member. (beyond the root)

The two original terms appear to contridict. Fillet Weld size is further confused as mentioned in Figure 25 and Fig. 26 (C & D) of A3.0 2001.

The depth of fusion *beyond the root* measured by macro etch does indeed produce a stronger joint than one fused only to the root (leading edge of the planes). With the thin materials used in this venue I understand the reasoning. (Beveled fillets require smaller leg lengths eh?)

I feel A3.0 may be a bit unclear here.. Figure 25 (B is a good for our conversation) is titled "Weld Sizes") However only *fillet leg* sizes are determined. Fig 26 View (D) I believe shows what our conversation is all about using the term "root penetration"

Fig 24 (E) also provides a fillet weld root that both represents the two planes and the depth of penetration.

I belive the term: "The joint penetraion shall extend to the joint root". Is either redundant or non sequiter.

I'm supposed to know this stuff and am now getting a headache.

Parent - By simons (*) Date 02-23-2006 11:49
THANK YOU! I Think everybody has helped to answer my questions. I really do appreciate everyones help. Thank you all very much!
Up Topic Welding Industry / Technical Discussions / Depth of Penetration

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