PRO HELP NEEDED: Fishy 1g test plate photos & opinions

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Hello everyone;I've been creeping around here for a couple weeks... and am impressed with the pros and sharp people here.I would greatly appreciate honest opinions from the experienced people here.  I had recently gone to re certify myself after being out of the trade for a while, and my certs expired.I was certified for structural welding, SMAW (stick) for positions 1-4G.  We always have done the combined weld coupon, with both the fillet (butt) plate and groove (beveled 30 deg). in the one unit with a 1/4" backing bar, and 3/8 plate.Now, after 2 months of practicing, I went in to do my test again... and was testing for my 1g and 2g (flat, horizontal) structural.  We use 1/8 low hy rod for the whole test.After some really odd/fishy business going on with my plate, my stuff came back as failures.  One is obviously broken... however, I have never seen nor heard of a coupon failing this way.I apologize about not having more detailed photos... but it's all I have to work with.We bend two root bends, on the outsides... which include one start/stop in each root, checked by the inspector.  The centre bend is a face or cap bend.You can notice the knurling... this is from the centre press... and indicates the inside of the bend.I greatly appreciate any notes on what you see here... I have a hard time understanding what has occurred.  The weldment failed in the middle of the weld, not at either plate which from what I understand is by far where most failures occur.  I also have a hard time understanding how the plates thinned and stretched on both sides of the plate.Lastly, I have a hard time understanding how plates put through a press for the 180 bend test exhibit NO curvature afterwards and are dead flat.I welded both 1G and 2G positions, alas, as the flat failed, the horizontal is not considered.I can tell you all that the horizontal was perfect except for some pinholes less than 1/64" and one or two 1/16 slits.  Not enough to fail according to what I've read.  The flat was exactly the same... no exhibited faults or fusion problems, just a few pinholes and one 1/16" slit.These were Lincoln 1/8" low hydrogen electrodes, loaded into a rod oven and warmed to about 250 4-6 hours prior to the test.  Rods were hot when picked up.  Two roots went in at 135 (room temp plate) and then back to 130 to finish the plate.All plates were hot rolled steel.  3/8 plates, with 1/4 backing plate.  Nice stringer bead went in at 45deg for the fillet, about 1/4 to 5/16 and even. No undercut.  Swept out the electrode to leave a longer crater for the stop.  Scratched my rod ahead then moved backwards to heat up for the start at the crater.  Next root pass was a nice hot weave about 1/3 up the bevel plate, and 2/3 up the fillet weld.  Same technique for the start/stop.  The rest was filled out nicely with fillet stringers and slight weaves.  Filled to flush with plate tops, and then ran 3 stringers to finish.  I ALWAYS wait for the hot puddle to melt into the fresh plate at the edges...  while tipping the rod so the puddle can wet up and fill the arc gouge... this is how I was taught, and every test I've done before (all the individual positions, and yearly check test, as well as many practice bends i've done for myself has passed with lovely results... worst thing I experienced was a few pinholes... Until now.At this point I must go through all the possibilities of what happened, before any further action can be taken on my part.I trust the good men here will help set me down the right path...TRUTH above all else!31221 Attached ImagesMiller Dynasty 200, Miller XMT 350... Looking eastward
Reply:I have to add:  I reason that the backing plate had mill scale on it, and was not removed prior to being tabbed up (supplied test coupons).  All were like this, and It's my fault for not dismantling and remaking the plate.  The mill scale is most likely the cause of the pinholes.PS, I'm not looking to hang anyone... I'm just completely flabbergasted at this.  I'm having no one able to give me likely reasons for this plate "explosion"  Hoping the peeps here could help!Miller Dynasty 200, Miller XMT 350... Looking eastward
Reply:Great White North as in Canada or are you in Alaska?I don't have much info on AWS related testing but the CWB stuff is easy to find.I typed in CWB 1GF and 2GF and this popped up from a shop South of me in Edmonton - I don't spend time typing out instructions that are readily available online. http://www.grbwelding.com/_CWB_Procedure_and_Rules.pdfFill your boots.Not to be snobbish but if you were previously certified in these positions, and have taken the tests before you REALLY should know the proper nomenclature for the test welds.Have a Good Night.Later,Jason
Reply:It looks like it might have had the piss ground out of it.  I would say it is down to ~1/4" in the weld area. I would speculate this is due to trying to remove gouging from where the backing was taken off.   I have seen more than a few bends pop right down the middle with no distortion of the plate.  The pictures suck, but the broken area looks like it has a good bit of LOF, and a nice big gas bubble.Experience is something you get right after you need it
Reply:Not taking anything snobbish...  I educated myself quite a bit years ago when I started, and yes, I did actually see that PDF you were referring to.Actual CWB documents are $$$ and hard to find.Yes you are correct, I was and am doing the combined fillet and groove plate.I appreciate the thoughts, I'm NOT looking for tips on how to weld, although I'm sure some will say I need them due to the outcome here...  I'm looking at some other failures here... as in what MODE of failure the metal underwent.I may have made errors, however... other issues seem more prominent.I am in Canuck land... born and raised.Honestly, thanks for any input. Originally Posted by Black WolfGreat White North as in Canada or are you in Alaska?I don't have much info on AWS related testing but the CWB stuff is easy to find.I typed in CWB 1GF and 2GF and this popped up from a shop South of me in Edmonton - I don't spend time typing out instructions that are readily available online. http://www.grbwelding.com/_CWB_Procedure_and_Rules.pdfFill your boots.Not to be snobbish but if you were previously certified in these positions, and have taken the tests before you REALLY should know the proper nomenclature for the test welds.Have a Good Night.
Reply:Fred s;THANK YOU!I appreciate the straight up honesty...  I also thought LOF... because nothing else made any sense to me.  A split straight down the middle with a square break is almost impossible IMO... the passes all overlapped significantly... usually target 1/2 previous bead if possible.Your thought of having the piss ground out of it... now there is one I missed.  Maybe that's why the "instructor/plate prep" person was so ****ing evasive about the whole affair.Thank you again... best I could do in the short time I had.BTW, you ever even heard of a refusal to have your own failed weld coupons? Originally Posted by Fred sIt looks like it might have had the piss ground out of it.  I would say it is down to ~1/4" in the weld area. I would speculate this is due to trying to remove gouging from where the backing was taken off.   I have seen more than a few bends pop right down the middle with no distortion of the plate.  The pictures suck, but the broken area looks like it has a good bit of LOF, and a nice big gas bubble.
Reply:I guess most of you can see.... that this isn't the plate number I was given for my test... it was ground out and changed.Don't even know if it is the same coupon I welded on.All questons referred to the "instructor/plate prep person" were avoided, and no answers given.My coupons were also refused to me, other than a few minutes to examine.Sorry 'bout the pictures, they ware the best I could do given the circumstances.Miller Dynasty 200, Miller XMT 350... Looking eastward