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Up Topic Welding Industry / General Welding Discussion / nr-232 advice needed
- - By BretSteel Date 01-18-2007 22:53
We have been working with nr-232 .072 diam.  This is a new wire to us (nr-211 for years).  The wire runs so different from the 211.  Can anybody offer up some advice for working with this wire.  We have an upcoming project that has to meet FEMA-353 standards.  We are attempting to master this wire for vert. up.  Any advice would be much appreciated.
Parent - - By XPERTFAB (**) Date 01-19-2007 06:37
Felt your pain at one time.  I'm short on time to answer this one today but look for the posts put up by Blaster as he too is very experienced and articulate on this wire.  Hell of a guy!  Like to weld with him someday!
If the 232 is a need for FEMA or LA City spec. Quickly give NR-233 a try as it might be an easier go for you at this time.  Both wires are much different than the 211 you have been using.  Will try to add additional info if needed.
Parent - - By BretSteel Date 01-19-2007 14:51
FEMA code brought me to experiment with 232.  I have read Blaster's posts, and they have been helpful.  233 may be an alternative, I'll research. 
I have gotten some porosity (high voltage?  drag angle?)  Steel is clean, wire is fresh, preheated steel.  Moisture in the air is high.
Parent - By aevald (*****) Date 01-19-2007 15:33
Hello BretSteel, voltage could be an issue, but, not as likely as the correct or incorrect combination in this case, of voltage and wire speed. If the voltage is relatively high and you aren't running enough wire speed you will generally have real spotty slag coverage of the finished weld, you may also feel a sense of having to wait for the puddle to keep up with you and the edges of the bead will not want to wet out very well. Wire stick-out could also be the culprit here. If you are running too short of a wire stick-out you won't allow for the fluxes to preheat and burn properly in the arc and maximize their purpose. With the diameter of wire that you are running I would probably try to maintain a 3/4" to 1" stick-out. Hope some of this has helped, good luck and keep us posted of your progress. Regards, aevald
Parent - - By Blaster (***) Date 01-21-2007 21:46 Edited 01-21-2007 22:23
NR-232, .072", works incredibly well vertical up.  It puts welds in fast, flat, and is not prone to undercutting.  All info below is for vertical welding: 

Wire Speed:  I like wire speeds in the 100 - 175 IPM range.... I don't generally don't go above 150-155 IPM unless the iron is about 1.5" or thicker.  135-150 IPM is really its vertical sweet spot.  The exact optimum speed is highly dependent on base metal temperature, material thickness, and whether the pass is a root, fill, or cover.  If a root, of course fit-up will affect best WFS as well.  The lower speeds I use, 100-125 IPM, are for very light iron, and stringer cover passes - such as for capping Chinese verticals.  In a real pinch I may go as low as 80 IPM, combined with a short stickout, but only if special circumstances call for a real small bead - I try to avoid ever going below 100 IPM.

When putting in a pass, it is vital to watch the leading edge of the puddle.  232 has a heavy slag, that is one of its great attributes, it allows carrying alot of metal vertical and overhead.  However it also can be very unforgiving if proper technique and parameters are not being used.  If the puddle looks like a horseshoe (U) with the open end in the direction of travel, you can be pretty sure you are running the puddle over the top of its own slag, particularly on a root pass on a groove weld with backing, or on a fillet.  Generally the aswer to this is to add more amperage by turning up the wire speed, however there are other factors that effect this too which are talked about below.

Correct wire speed is everything for proper performance.  I recommend verifying the WFS reading on the wire feeder at several settings across its range by using a tape measure and watch.  While I have always had good luck with LN 25s, some feeders on the market I have used have had horribly inaccurate WFS readings / indicators.

Voltage:  Use CV output (DCEN).  The wire is very voltage sensitive and there is no good reason not to use the preferred output type.  Voltage readings on feeder meters can be misleading.  Off the top of my head, I think Lincoln recommends an arc voltage range of something like 16-23 for this wire and diameter.  However the length of your leads, ground path, quality of connections, etc. will continually change what you need for a feeder meter reading on a given joint.  Once the wire speed is set to a proper value, what you want to do is adjust the voltage up or down to control the arc length and how closely the slag follows the electrode.  I like to start with the voltage a little low to where the wire is hitting the puddle, and then add 1 volt at a time until the transfer clears up.  Fine tuning is done in 1/2 volt increments.

If the voltage is too high for the wire speed, the first sign is "chicken tracks" on the surface of the weld.  If the voltage is grossly high, there will be visible posity.  In both cases the slag will darken in color.  When the voltage is too high, the slag will lag behind the electrode and then split below the puddle.  You will have two lines of slag following the puddle, one on the right and one on the left, and a whole mess of metal going wrong (falling out) in the middle.

If the voltage is too low the wire will stub into the work and the slag will flood the arc.

Use voltage meters!  The welders need voltage meters.  They need to be able to make accurate 1/2 to 1 volt adjustments to their feeders when dialing in voltage.  Each time the welder changes his wire speed to get more or less amperage with this wire, he will find he needs to adjust about 1 volt on the feeder meter for every 25 IPM of wire he adds or subtracts... similar voltage adjustments are necessary as leads are added or subtracted from the welding circuit.  A good 232 welder will be making continual adjustments to wire speed and voltage as he goes from root, to fill, to cover, to a different position, and to compensate for changing base metal temperature.  He needs a voltage meter on his feeder to make minor, accurate changes quickly for best quality and most effecient welding speeds.  (He also needs a feeder with an internal contactor!!!  'Nother story there but after having to use some without, damn, why Lincoln would ever even field a feeder without an internal contactor I will NEVER understand.)

Angle:  If wire speed and voltage are dialed in perfect, I like to float between a slight drag and a slight push.  Generally a slight drag at the bottom of a joint and then transitioning to a slight push during travel up the joint as the base metal heats up.  The drag is needed at the bottom to displace slag from in front of the puddle, and as things heat up, a push can be used to direct heat away from the slag shelf so that it (the slag) will continue follow closely below the electrode.

Generally a slight push (and slightly lower wire speeds) works best for cover passes as the virtually flat surface that is being welded upon will not dissipate the heat away as quickly as when down in a groove.  Therefore the slag follows best, and allows the flatest beads, if you aren't directing arc heat at it.  There are exceptions though - if you are putting in thick cover passes a slight drag may still be needed to displace slag from in front of the puddle.

Stick Out:  I like about 3/4" - 1".  Stickout can be adjusted slightly on the fly to tweak slag follow or to displace slag from in front of the puddle, however the wire speed and voltage should be dialed in to where much of these stickout adjustments are not needed.  A reasonable stickout allows the fluxing compounds in the wire to be preheated or "activated" by resistance heating of the wire.  This can be very important with wire that is being used even though it is not fresh - no I don't condone using old wire.

Base Metal Temp:  Of course it should be within the range allowed by the procedure.  However as far as controlling the puddle, 232 can put down nice looking and clean welds between 100F - 500F no problem.  However the welder will need to have the understanding to make minor adjustments to the WFS, voltage, travel angle, etc as appropriate to compensate. 

Bead Width:  About 5/8" seems to be the sweet spot.

Technique:  232 is a great wire but the techniques are different than 7018, T-1s, T-11s, etc.  Foremost the welder must understand the relationship between, WFS, voltage, electrode angle, stickout, joint geometry variations, base metal mass, base metal temperature, and how changes to one effect, or can be compensated for, by another. 

232 is all about keeping slag from getting under the front of the puddle, while keeping the slag at the rear of the puddle forming a continous shelf below, and close to, the electrode.  I like to start at the bottom of the joint with a short stickout, maybe an 1/8"-1/4", so that my start will flatten out immediately and will be hot enough to prevent any slag or porosity from freezing in the area.  I move pretty quickly a few times from on side of the joint to the other to establish the slag shelf.  If it is a heavy joint and I therefore have the WFS cranked well up, I may let off the trigger a few times for a second or two so the slag shelf can be established more easily - at higher WFS there may be too much heat to get the initial shelf established if you keep the trigger back - you may just end up melting off the run-off tabs or boring a hole in the joint.

As the slag shelf is forming and things are warming up, I slowly lengthen my stickout to normal length.

Once the shelf is formed I wiggle the wire side to side slightly (not weaving) so it won't bore a hole into the base metal (which then adds so much metal to the puddle it spills over the slag shelf.  At this point I really care about closely watching 3 things.  First that the leading edge of the puddle is not "U" shaped in the direction of travel as stated earlier.  Second that the slag shelf stays continous from one edge of the bead to the other.  If it splits down the center, the puddle will fall out almost immediately.  And third, that the slag shelf follows closely below the electrode.  Vertical travel should be slow enough that the wire never gets more than maybe 1/8" or so above the slag shelf.  Sometimes I like to travel vertically slow enough that the slag shelf actually bumps the bottom of the wire from time to time.  If you get the wire much ahead of the slag shelf, the slag that is running down from the top of either side of the puddle will solidify to the point that it won't join back together below the wire.  Now you have a split in the slag shelf and the bead will spill out.

Do not weave.  If you let one side of the bead freeze, like you would with say 7018, the very heavy slag will interfere with the puddle when it is brought back again.  You will also find if you weave or don't keep the puddle hot, when you go to chip off the slag there will be a light layer of what looks like sand left stuck to the face of the weld that is a real bear to get off.  You want to keep the puddle hot and fluid.  This prevents slag inclusions, give excellent tie in at the edges, results in a flat bead, and allows the slag to come off very nicely, much of the time self-peeling.

Fresh Wire:  232 is not near as tolerant of moisture contamination as some other FCAW wires.  The welding performance diminishes noticeably as it picks up moisture.  It won't weld "right" and chicken tracks will start to show even with proper set-up and dial in, eventually visible porosity will become a problem.

Surface Contaminants:  232 has very low tolerance for crud.  Adhesive, paint, even moderate rust can cause problems for this electrode.  Burning out/off a joint with a torch and preheating help.  A chisel scaler can be helpful for rust and heavy mill scale removal.  But sometimes, such as with shop installed backing bars with no backside access, there is just no getting around still having to put in a pass to burn out the crud, air arc it out, and repeating as necessary until the root is finally clean.  I was on a job where the joint surfaces where all duct-taped at the fab-shop sometime prior to "protect" them.  Of course much of the iron was errected and bolted together with the tape in place and trapped between mating surfaces.  All of the tape was so deteriorated that even when you took it off the adhesive stayed stuck to the surface.  Bah! When that is between a backing bar and the back of the joint, no torch work can burn it out adequately enough to prevent fouling of the root pass.  What will be inaccessible areas of joints should be reasonably cleaned prior to bolt-up.
Parent - By agong (**) Date 01-22-2007 14:29
Parent - By BretSteel Date 01-23-2007 21:24
Blaster, I thank you sir.  Your explanation is just what I was looking for.  It will take a little time to fully comprehend and apply what you have layed out for me.
I'll post my results and/or any questions.
Parent - By CV Weld Date 01-26-2007 15:07
That is a great reply. I have all thoses thoughts in my head but could not have explained it as well as you.  Some of us (YOU)are great teachers and others well.  Nice job explaining.  To add one note  2/0 (Minimun)weld lead as short as you can go and also as the day goes on and your weld generator gets warm, voltage adjustment may be required for sure.  Don
Parent - - By Blaster (***) Date 05-10-2011 14:27 Edited 05-10-2011 20:09
I want to add a couple more 232 tips for other positions (flat and overhead) as when guys ask me about T-8s / NR 232 I usually refer them to this thread:

For flat I like 225 IPM minimum.  Sometimes maybe a little more, but generally that is my favorite speed for flat (or horizontal fillets).  If you go slower on the wire speed it becomes increasingly dificult to avoid including slag, particularly on heavy steel and on tighter grooves.  One of the more common mistakes is running the same parameters used vertical for the flat position, or vice versa.  The optimum numbers for each are substantially different.  I like a fair bit of drag in the flat, a medium stickout, and put each bead in hot, fast, and thin.  232 is most prone to slag inclusion in the flat position.  The most common reason is travelling too slow and/or running too low a wire speed.  It is particularly important to start with a very short stickout (for the first second or two) when starting in a rat hole on the topside of a bottom beam flange to avoid LOF, inclusions, porosity, and overlap.

For overhead I like 130-150 IPM.  In a groove a slight drag works well combined with a stickout on the shorter side.  Covers seem to prefer 0 degrees drag, a stickout on the long side (maybe an inch), and a slower travel speed to provide the heat and time needed for the puddle to wet out flat.  I like a little more voltage overhead than for vertical at a given wirespeed.  It keeps the wire from digging up into the joint, and helps to get the puddle to wet out flat.  An important thing is to have somewhere for the weld metal to go.  A common mistake is to overfill the joint prior to starting the cover.  Then the travel speed for the cover must be too fast to achieve a really nice appearance.  Travelling too fast, the weld has a tendency to become ropey at the toes and irregular in height.  The ticket to a nice overhead cover is too carry an adequate amount of metal on each pass.

232 seems to weld better overhead than any other position, and it is possible to carry a fair bit of metal in this position.  Slag inclusions are comparatively dificult to obtain 4G, and a good cover will be very flat with the slag pretty much falling off.
Parent - - By weldstudent (**) Date 05-11-2011 04:58
if i had only found this before i ever touched the stuff, well i learned a lot running vertical with 225-300 IPM about 5-15 volts higher than needed. kinda glad i didnt find it untill after i learned how to cuss better.
Parent - By Blaster (***) Date 05-11-2011 14:19
Haha - thats pretty funny.  :lol:
Parent - By Joseph P. Kane (****) Date 05-10-2011 16:32

Wow!  That is a great reply!  Very informative. Very comprehensive.

Joe Kane
Up Topic Welding Industry / General Welding Discussion / nr-232 advice needed

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