I am not aware of any benefit from increasing penetration further than what is necessary for thorough fusion.
However, increased penetration will imply increased heat input, and therfore all of the metallurgical fallout from that. This could actually be negative depending upon the alloy. You will also see increased dilution with increased penetration, again a possible negative, depending upon the alloy
I would clamp the bottom plate down to a good, thick heat sink, and then make your welds with two stringers on each side. Allow the material to cool of somewhat between passes. If you stagger your beads with one concentrated on the upper plate and one concentrated between the first bead and the bottom plate, you'll still get plenty of penetration.
Tim
I agree with Tim that clamping the plate is the most likely way to controll the distortion. The hot metal is going to shrink as it cools, no way around that. If You keep the plate clamped flat the material has to elongagate [or crack] when it cools. If it doesn't crack You should be OK.
Hello Kix, I believe that you will find that deeper penetration will do nothing for the strength of the weld joint. In fact the additional penetration may very well add more shrinkage stresses into the joint and promote cracking issues in some cases. As long as the penetration is to the full depth of the joint so as to prevent root cracks from developing, you should be safe. Two small passes vs. one larger pass can be somewhat of a give and take, the two smaller passes will have less heat input into the part, yet they may introduce more stress. The one larger pass might result in less residual stress but may cause other issues due to over-heating the base metal, in the case of heat treated aluminum alloys this could mean an irreplaceable strength loss in the HAZ zone of the weldment. I believe that SWP had the correct response for you with regard to the distortion that you experienced in this T configuration, I believe that restraint of the joint and proper heat sink placement will minimize the problems that are occuring in your set-up. You will certainly need to do some experimenting to end up with the best result. Good luck and regards, aevald
Ok i'm finding that when you let the bead grow to over 5/16" it starts to spray better and you can see that it is penetrating very well. If i try to hold a 1/4" fillet it goes in real nice and slick and my travel speeds are a lot quicker, but i'm not getting consistent penetration. In order to get it to spray somewhat decent in a 1/4" fillet with this .062 filler i'm haveing to up my volts a bunch. So is this telling me i should drop to a .045 wire and i will get my 1/4" fillet and my spray and penetration at a lower voltage?
Hello Kix, yes I believe you could approach it that way and end up with more consistency on the smaller fillet weld size. Regards, aevald
On fillet welds more penetration can reduce the size of weld required by quite a bit.
JTMcC.
So then i need to find out how much pen they are requireing for the 1/4" and 5/16" fillets the print is calling out?
JTMcC,
Can you expand on that. I don't understand.
Someone said above that you can reduce the size of the fillet weld requirements with more penetration. So i'm wondering if the have a certain penn requirement for the 1/4" and 5/16" fillet welds they are calling out for joining two 1/2" plates together.
Hello again Kix, I somewhat understand what JTMcC was referring to with penetration versus fillet weld size, however, I also see the possibility that the engineering behind the joint could be altered by changing this configuration. Typically weld sizes for fillets will be sized according to the thickness of the thinnest member and depending on the service of the joint, will be welded on either one side or both, depending on that service. In my opinion, a fillet of the correct size on both sides of a vertical member will have much better strength than say a full penetration weld that connects a similar vertical member with little or no build up in the form of fillets on both sides. As I said, this is simply my own opinion. Regards, aevald
Kix,
The JF Lincoln foundations has a interesting web site, Welding Innovation Vol. XV, No. 1, 1998 has an article in it addressing penetration vesus fillet weld size -Link below
http://www.weldinginnovation.com/innovation/back.aspI've also seen an artical addressing distortion but I can remember which issue it was in.
Hope this helps.
js55
i think he is referring to situations were you can't make the required size fillet due to shape of parts. it is typical for engineers to allow an equal size pjp in place of the fillet. this is of course only done with the approval of the engineer.
If you take two 1" plates, in a T configuration, you could, if you wanted, make a full pen weld at the joint and have little or no weld reinforcment. Or you could put fillet welds down both sides till you achieve the strength you need.
When you achieve greater penetration (usually thru the use of flux core) you increase the effective throat of the weld.
According to ESAB reducing the exterior size of the fillet by as little as 1/16" can reduce total required weld metal by up to 50% or 60%.
So the real savings is in weld volumn required. The included angle and the root opening dimensions can be reduced in groove welds and that reduces the amount of weld metal per joint. The increase in penetration removes a lot of the risk of "lack of fusion" defects in the narrower prep. Out of position the flux core wire will usually be run at higher amperage than solid wire or stick, again lessening the risk of LOF problems.
I think this is why flux core is used in so much heavy manufacturing such as Cat. Reduce the amount of weld volumn in their world and you've saved large amounts.
Of course I'm not recomending home brew recalculation of fillet weld size because you went from solid wire or stick to flux core. But in the right circumstances you can take great monetary advantage of those lower volumns of weld metal deposited.
That's my take.
JTMcC.
If I'm looking at it wrong, I'm sure some one will soon point that out. But Esab and Lincoln pretty much agree with my view. Or more accuratly, I agree with their view ; )
JTMcC,
I understand what you are saying now. Thanks. And without looking it up, this is addressed in D1.1 somewhere if memory serves.
And if one is to established such a process then it would be necessary to qual, etch, do mechanicals of course, and then maintain a minimum heat input in your WPS to ensure you are getting the required penetration. Correct?
And is there an industry standard level of volumetric inspection (UT for example) to verify this?
I don't have any idea if D1.1 addresses this, or even if there is a mechanism to take advantage of the increased penetration on fillets in structural steel work. Others would know a lot more about that than I do.
I do however think that heavy manufacturing has been taking advantage of it for years. Of course when a company welds together a dozer or shovel or any other heavy iron, they are the deciding factor in how much of what type deposit to apply rather than a code.
And end users, who end up doing large amounts of maintenance/rebuilding/modification type welding on the equipment sometimes take these things into account.
JTMcC.
When all else is equal, more penetration is better. The closer you get to having a weld nugget with parallel sides in the cross section, and penetration through the material, the less angular distortion you will have. Picture it this way: if you saw a wedge or vee out of a flat bar, leaving a hinge at the apex, then bring the cut surfaces together, you will have a certain amount of "angular distortion". Now cut all the way across at lesser angle (closer to parallel but not 90 deg), and bring the cut surfaces together. Your "angular distortion" will be a lesser angle. You will still have transverse distortion, but the angular distortion will be less.
Naturally though, you want to avoid a wider weld face unless the root/face width ratio will be less. Otherwise you get a wider "saw cut" with a hinge still in place, which will mean more distortion.
One thing I would explore is prebending the parts in the opposite direction so the weld is free to shrink naturally and you end up where you want to be. If your welding parameters are consistent, your distortion should be as well. But remember that different yield strengths from different heats will bend a different amount; close but not necessarily equal.
Topic Welding Industry / General Welding Discussion / Ok i'm stumped and need some input from you distortion pro's
