I'm doing an all position plate test the plates are 3 x 6 x 3/8 with a 60 degree bevel on each plate. Root opening is 1/8 inch land is 1/8 inch ( my personal choice). 1G, 2G, 4G are all 6010 root. Flat and o/head are root fill, and cap while horizontal is 6 pass including root. 5G is 6010 root 7018 fill and cap.
My problem isall my roots pass a guidid bend test but flat, horiaontal and overhead are all breaking beside the weld. The breaks show no inclusions or porosity and look like a malleable cast. The 7018 plates bend without failing on the root and face bends but the others don't.
Any ideas would be really appreciated.
I run the roots at about 70-75 amps, fill and caps about 5 amps hotter depending on the machine. Overhead is slightly hotter.
Are your plates cut so that the grain (rolling direction) is running the 3 inch direction? That can make a difference.
CHGuilford
Actually the palte is cut from a 6 x 3/8 flat bar so I would imagine I'm welding across grain but bending with the grain?
are you grinding the root pass down a little before you put the hot pass (2nd pass) on? if you're not doing that, then you might have some wagon tracks, slag inclusions, or other nastys hiding in the crevices left from the root pass. your vertical up welds might be passing because 7018 is a relatively slow rod. that means that more heat is put in, and those wagon tracks are melted away. vertical up also tends to get more penetration than the other positions because the arc melts away the base metal, and that metal flows downhill, blending w/ the welding rod metal.
also, some people swear by using 7018 for a hot pass. some people swear by 6010. I myself like using 6010 because I know it works (passed all my certs. w/ a 6010 hot pass). 6010 penetrates a lot, and it freezes fast when using whip and pause technique. so, what I do is grind down the large hump in the middle of my root pass and then whip and pause a quick bead of 6010. then i grind that down a little and continue on w/ 7018. a hot pass also tends to refine the grain structure of the root pass by heating it up. lots of times the root pass cools off so fast that it's brittle and needs to be annealed (heated up to a cherry red color).
oh, and when you wrote "5G", i assumed you meant "3G", since you're not welding on pipe...5G is a pipe laying in the horizontal position.
good luck!
Unfortunately the test doesn't allow for grinding, filing or anthing other than a slag hammer and wire brush. My vertical is actually at a 45 degree angle in front of me (halfway between o/head and vertical) I tried turning up my heat about 5 amps after my root to burn into the plates more and burn out any slag that might have been caught in my corners but they still break. The root passes are bending fine so I don't think there's a problem with hard spots in my roots. Is it possible for mild still to become austenitic beside the weld? The breaks look wery similar to cast iron and are right along the fusion line. Also I remember reading that to acertain degree the more rod angle the more penetration.
I'm making sure that my root pass is ABSOLUTELY clean (pick, slag hammer and wire brush) berore doing my hot pass so I don't think slag inclusions are a factor....but you never know.
By the way, thanks for taking the time to reply
yes, there is a heat affected zone (HAZ) in every weld. that could be your problem too. i'm not sure that mild steel would develop a HAZ that could be hard enough to break the way you're describing. i know medium carbon steel has a problem w/ the HAZ getting too hard. maybe the other guys in here know something about that...
try a hot pass about 10 amps more than what you do your root pass with. that's about all i can figure.
I'm just curious, why are you taking the "all position" test. 1G, 2G, 3G, and 4G when 3g and 4g qualifies you all positions under AWS D1.1, "section4.18.1.1. Welders. The production welding positions that a welder is qualified for shall be in conformance with table 4.8." CJP, and PJP welds are covered, as well as production pipe welding... Maybe because of the bevel angle, you may be qualifying for a unprequalified joint, but it still had to be qualified per any code...back to the queston at hand, why don't they acid etch the samples before they bend them? I've done that for 308-L tests at nuclear facilities on carbon steel A36 because it's not normally going to bend around before it breaks, but I have made that test numerous times. Perhaps another idea, you could X-ray the coupons. If they insist on bending the specimens, put a radius on the edges, and don't grind longitudinal to the weld. If in fact there is some slag or LOF in the toe of the root or fill passes, and it doesn't show, the inspector won't look at the coupons near as long if the grinding marks are across the face, and not with it.
I agree with Boilermaker, sounds like you got your positions mixed up for an all-position plate test. 5G is a pipe position. All-positon plate test under ASME IX is 2G, 3G and 4G.
In any case, I've seen the problem you describe with the face bends quite a bit. It is likely due to the rolling direction for the flat bar being parallel to the weld and tranverse to the bend specimen, as was already suggested. I have also seen it occur when the cover pass is very wide. Could be the 60 degree bevel on each plate (120 degree included angle) you described. Reduce the angle to 37-1/2 deg. per side for open root E6010.
Marty
I stand corrected. Actually the plates are 30 degree bevel each side 60 degree total angle. Again, this is the required angle for the test. The test is a journeyman Quailification test in Alberta canada and is required to do any pressure testing(I believe it's the equivilant of an CWB A ticket) with 4 1/2 or more years expeience as a weldor you can challenge this test and recieve a journeyman ticket. This ticket allows you to work in Alberta as a certified weldor. A "red seal" test allows a weldor to work interprovincially in Canada.
I'm goint to try cutting my plates longitudally and see if that helps. As far as ASME codes I'm not sure if they're used in Canada. I believe the testing organization is the Canadian Welding Bureau(CWB). Any pressure, tig, mig etc...tickets are done through them
The ASME IX codes are for your pressure vessel & high pressure pipe welding which need to be qualified through the different provinces Dept. of Labour. CWB testing is for structural steel & production type of work (which are items resold to the public and are CSA approved). These are two separate entities, a ticket in ASME IX is not valid for CWB. A CWB issued ticket is only valid for 90 days unless you are working in a CWB certified shop or i believe union as well (ironworkers). correct me if i'm wrong.
Well, I was about ready to take up a new trade...seemstress, hairstylist, and thought I should get one of the other guys in the shop to burn some plates together and guess what....they broke in exactly the same manner as mine have been breaking. It made him feel not so great but it sure made me feel better. I'm not sure what to do now but I thought I'd say thanx to you guys for all the input.
I'd gotten to the point of being counterproductive with changing heat, rod angles, fitup, amperage etc... now all I've got to do is find some new GOOD steel.
thanx again
From your response you are already cutting the test plates correctly as far as grain direction goes (3 inch long from a 6 inch wide bar). On the assumption that your electrodes, technique, etc. are good, you might try using bar from a different heat number or even cut the coupons from plate. If allowable, you might try using a grade such as A992 that might have a better grain refinement. For that matter- I didn't notice if anyone else covered this- but you might try a different lot of electrodes. We have had similar problems with skilled welders failing seemingly simple tests and changing the materials used made the difference.
Hope this helps, keep us posted.
CHGuilford
I phoned the College this morning and talked to the head instructor there. After I explained about my procedure, problems and my possible career change the first thing he said was, "sounds like a bad lot of steel, did you get a mill report??"
I'm off today but tomorrow I'm going to get some coupons from somewhere else and keep my fingers crossed. I let you know how it goes. I'm not supposed to use scissors since the accident so I was definately not looking forward to a career change.
tq
tq,
this might be a stupid question but are you bending the coupons to the specified radius for the material and thickness?
There's no such thang as a stupid question (only stupid answers).
I don't think the radius is the problem because it's same radius the testing station is using.
tq
tq,
well it seems like you have checked out everything else. you may just want to double check the radius. I was call by one of our clients that had a similar problem, come to find out they were bending the coupons at too tight of a radius.
I tried the different plates and the same results were had. I'll try phoning the testing facility tomorrow and find out at exactly what radius they use and whether or not they are using rollers to decrease resistance during the bending. I know I can hear the plate "howling" a bit euring the bend. On the positive side, the plat actually broke about 1/4 inch form the weld as opposed to directly along the weld today so maybe progress was had.
I've found it to be beneficial during testing to not put in any weave passes over 1/2" wide and to use a temp stick to ensure that the test plate is below 600 degrees between passes. Also be sure that your 7018 rods have been properly oven stored and have not been exposed to any type of moisture or out of the oven for more than 2 hours. (moisture contaminated flux on low hydrogen electrodes causes under-bead cracking which is not visible on the surface and could possibly be your problem)
I agree with Wild T on bend radius, esspecially if the base metal is breaking outside the weld area or HAZ, check the yield strength of your base metal and compare to fig. 4.15 AWS D1.1, not familiar with CWB but it also should have provisions for the yield strength of test coupons.
Problem solved.....finally, 6 weeks of bending and breaking not to mention all of the ideas from you guys as well as the guys at work and believe me, I tried every last one of them.
The problem WAS the material. I clued in today when I was watching my boss bend a piece of 3 x 3/8 flat bar in the manual bending machine and he's grunting and huffing and says "*#&$ this stuff is hard to bend"
Well, I'm thinking, maybe the carbon content of the flat bar we get is higher than mild steel flat iron should be. So I go outside and find a small piece of 8 x 8 x3/8 square and cut two 3 x 6 pieces from it.
Bevel it with the torch, put on my land, set my gap, tack it to my stand, and weld, weld, weld. Then I torch it in half, let it cool and subject it to what has become my personal nemisis..the bending machine.
Sweet as pie and easy as you please two perfect specimens are bent right before my eyes . So I try a couple more coupons in various positions, bend them, and not a crack, split, or break to be had.
Like I said before, thanks to all for the input and great ideas.
Dave
well, at least you got lots of practice, and you're VERY qualified for the job now! *smiles*
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