Started work on a new project fabing 6" sch10 tp312 304L welding with 308. Been welding same size pipe with 308L on last project. The new pipe is all from tubacex in spain, 308L filler is for this job only. I don't remember manufacturer. I'm running 10 amps hotter (95 amp) to get it to breakdown the bevels but the root still doesn't want to spread/widen out like the last job. The 308L filler seems to run alittle like inconel( molten puddle is cloudy/hazey). How big of a difference could there be between 304L from different manufacturers? Also 308L filler wire, How much differences from one brand to another?
We did clean the 308L filler with no noticeable difference. Root gap is between 1/16" and 1/8".
There can be a tremendous difference and I suspect its in the Si and/or S content (notorious in SS's). These elements (a lack thereof) are ususally associated with problems of wetting and fusion.
Thanks for the reply. We figured out how to weld it today. We're welding it as if it were 317, keeping a key hole all the way and its looking good. Just amazing how different this job runs compared to the last one.
I'm guessin you still have the same problem. The reason that keyholing works is that the material is sluggish (a little higher in viscosity-or greater surface tension) when molten and allows easier control of the keyhole and the wire feed. You can keyhole on any alloy but it takes greater skill, more precise bevel and torch angles, greater control of the weld parameters and is just plain not worth it on alloys that wet well and are low in viscosity.
Interesting reading. I wish they would have explained the key word Gaussian Power. Plasma Shear Force is what I'm going for. According to the article I need more power. Then I will not have to depend on thermocapillary flow reversal.
Perhaps these articles may enlighten you... Although I warn you, the math isn't for the faint-hearted!!! Note: Giovanni! You may be interested in the first two links! ;)
Here is a very interesting article regarding software capable of solving various equations related to welding, casting, upsetting and extrusion computational modeling and thermal stress analysis, etc.
Unfortunately, there is really nothing you can do with weld paramters to overcome the outward, shallow and wide flow pattern of a "low sulfur" themocapillary flow. Cranking up the current will increase arc force, but it also just drive the existiing fluid flow more strongly. The best solution to a low penetration heat of material is to change the batch of steel or use the penetration enhancing flux sold thru EWI.
Your words have proved true. Cranking up the amps did not help. The puddle gets bigger but it then begins to wander. I ended up turning the amps down and going much slower.
Perhaps these articles may enlighten you... Although I warn you, the math isn't for the faint-hearted!!! Note: Giovanni! You may be interested in the first two links! ;)
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