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Up Topic Welding Industry / Technical Discussions / CVN test failed!
- - By Nandesh Kumar (*) Date 12-17-2009 14:04
Gentlemen,

I'm new to this forum.

Just now I'm coming out from lab. My CVN test is failed!!

kindly give some inputs.....

Material ;API 5L GrX60 pipe
thk ; 19.1 mm
Dia : 24 inch
Root and hot pass :GTAW ER70S-6
others : SMAW E7018-1 H4 R

My welder welded it in PF (5G, uphill) in order to qualify the pipeline WPS.(all welding variables followed properly, including preheat) The  code we are following is ISO 13847 along with shell DEP. During welding, at 3' O clock position (the portion required for CVN testing), he felt that the base metal is not melting properly and he cut it and again welded it. He repeated it 2 times. Finally he completed the welding and it passed all the tests, even tensile, macro, hardness, bend test EXCEPT CVN!!! The values I got for CVN at weld center line was less than the required.

Can anybody please throw some light on the CVN failure?

respectfully,
nand7400
Parent - By 3.2 Inspector (***) Date 12-17-2009 14:28
I guess you are following EN 15614-1 for qualification of the WPS?
ISO 13847 seem to be a construction standard.

3.2
Parent - - By js55 (*****) Date 12-17-2009 15:30
Help us out here.
What test temp?
What specimen depth/location?
What were the results?
What heat input?
What do you mean by 'cut it'?
Parent - - By Nandesh Kumar (*) Date 12-18-2009 04:48
Gents,
ISO 13847 is not a construction code it says all about qualification of WPS , NDT, DT as well as production weld.

Test temperature is -31°C
specimen size as per ASTM A370, notch depth 2 mm form the root
Test results of 1 set ( 3 specimens) : 13, 20 & 21 (required is minimum average 41.64, individual 29.64J)
'Cut it' means , he removed the complete weld deposition and rewelded it.

Thanks in advance
nand7400
Parent - By MMyers (**) Date 12-18-2009 05:08
Were these center weld or HAZ charpies, and do you have any info about lateral expansion or percent shear? 
Parent - - By js55 (*****) Date 12-18-2009 14:16
Even though GTAW root/hot is represented in a CVN specimen the specimen will still predominantly be the SMAW process. Also, often with the first SMAW fill over the hot pass, (most of what will be represented by the specimens tested), the pass will sometimes be perhaps the thickest pass in the weldment (the bevel restricts the weld metal from spreading as opposed to higher in the bevel).
I have always argued that heat input is an overrated variable when it comes to success in impact tests. To me what is more important is recrystallizing the as deposited weld metal. The thicker the deposit the less of it that gets recrystallized given an equal heat input of the pass above it.  Recrystallized microstructures generally demonstrate better impacts(for most alloys). Many times I have actually increased heat input to obtain better CVN results. And for the very reason of increasing the recrystallized portion of a previous bead.
I do not know for sure that your material can achieve the requirement, but a thought would be to either increase the volume percent of GTAW in the specimen and/or reduce the thickness of SMAW beads thereby increasing the volume percen tof recrystallized microstructure being represented.
Parent - - By ssbn727 (*****) Date 12-18-2009 18:05
That's a much better way to approach it I believe! Recrystallization is far more important IMHO as Jeff so eloquently pointed out. ;) Too many folks focus on the base metal metallurgical aspects and distract themselves from concentrating on the weld metallurgy which is far different than what the base metal is telling them, so they forget time and temperature with respect to letting the weld recrystallize enough so the the grains are more refined, and instead rely too much on heat input control alone when considering how to achieve optimal CVN values. ;) Great Post Jeff!!! :)

Respectfully,
Henry
Parent - - By js55 (*****) Date 12-18-2009 18:14
Thanks Henry.
The grains in recrystallized weld deposits are also equiaxed as opposed to columnar, which is indicative of 'as welded' deposits and this equiaxed strucure makes fractures paths a little tougher to follow. to put it crudely.
Even the unrecrystallized portions can be tempered. Though still columnar they are stress relieved.
Parent - By ssbn727 (*****) Date 12-18-2009 18:26
That's not putting it "Crudely" at all Jeff! That's hitting the proverbial nail right on the head!!! :) :) Simplicity has it's own sense of eloquence! ;)

Respectfully,
Henry
Parent - - By js55 (*****) Date 12-18-2009 18:10
I would guess with 13 you are well below 50% ductile.
The 20 21 may be sitting at what? 50% ductile maybe, as a guess. Maybe a little more
You're moving towards the upper shelf.
Three things, related to my other post:
Watch your heat input (yes I know what I said).
Watch the thickness of your first SMAW pass. Make sure it gets tempered/reheated/recrystallized
Take a look at your coupon cross section with macros if you can and determine where in the macrstrucure the biggest volume percent of your specimen is located. Or, your lab should be able to tell you this.
Parent - - By Nanjing Date 12-19-2009 03:13
"required is minimum average 41.64, individual 29.64J"?

Is this what your specification calls for?

Forget about all the bull**** written.

U have made the wrong choice in welding consumables.

U should have went for something with 0.8% Ni content, a G class. If you did you would have no worries about your procedure or any possible production tests.
Parent - - By Nandesh Kumar (*) Date 12-19-2009 12:49
Thanks a lot gents, anymore inputs?
Parent - - By Nanjing Date 12-20-2009 04:39
Don't think you will get any more response from these clowns.

"The grains in recrystallized weld deposits are also equiaxed as opposed to columnar" what a load of irrelevant bull....!

Unless you are welding with robots forget all this nonsense.

Select the right consumable that will give you the guaranteed properties you need.
Parent - - By js55 (*****) Date 12-21-2009 13:48
In perhaps the, oh I don't 30 kackozillion carbon steel impact tests I've run I've never found it necessary to go to Ni for that temp. But of course the operative is to control your parameters. Which you have to do anyway.
There is nothing wrong with utilizing nickel but it is no excuse for perpetuating ignorance of the process. Therefore, I will grant you your crutch.
And of course being a 'discussion' board it certainly isn't "nonsense" as you say to try and provide for the poster some theoretical background to what he is trying to accomplish. Unless of course your thought is that you will always be around to berate your colleagues (I use the word loosely) and offer the holy grail of advice.
The other thing of course is, you could have reserved your spew for a private message. But, since you didn't (perhaps the primary point after all) keep in mind that many other people are reading these posts. Other people with applications with some variance to the original post but applications nonetheless wherein the technical knowledge can be valuable.
Parent - - By Nanjing Date 12-21-2009 13:54
Can some one please translate this into English?
Parent - - By jrw159 (*****) Date 12-21-2009 14:28
It is in English. Stop cluttering up threads with your useless drivel and insults please. I feel you have a lot to offer but this is not it.

jrw159
Parent - By Stephan (***) Date 12-21-2009 15:15
John!

I bow my head before you!

Thanks!
Stephan
Parent - By js55 (*****) Date 12-21-2009 14:30
I can translate it for you in two words, but again, there are many others reading these posts so I refrain.  :)
Parent - - By Nanjing Date 12-21-2009 14:52
ASME requirement is ER 70S-6 27J @ -30C. Topped of with E7018-1  which the ASME requirement is 27J @ -45C. (Does it say which welding position these are for?)

I would not put my house on the line for passing this with these particular consumables especially as the choice of the impact testing position is 3G position (standard I think) and temperature at a given requirement of 41.64J, individual 29.64J.

No, not a good bet at all!

As a sensible Welding Engineer I advise you to pick a welding consumable that will do the business.

Forget all these heroic comments "what I have done in the past attitude". When qualifying welding procedures make sure you select the right consumable that anyone can weld with.
Parent - - By ssbn727 (*****) Date 12-21-2009 19:07
It's minus 31 degrees C! NOT minus 30 C! Billy, Billy, Billy... Didn't I suggest to that you should go see an eye doctor before??? This is just another example which should convince you to go seek a remedy to your obvious eye problem. Note! This is not a personal attack or stab at "nanjing" It is merely a sincere reminder of a previous suggestion I made to him on a previous thread which I hope this time he will indeed take my suggestion a bit more seriously. ;) May I suggest Lasik! ;) ;) ;)

Henry
Parent - - By Nanjing Date 12-21-2009 22:20
Henry, have a look at A5.18 test temperature for ER70s-6 and you might see what I mean. If you still do not understand just ask and I will be glad to assist you further.
Parent - - By ssbn727 (*****) Date 12-21-2009 23:05 Edited 12-21-2009 23:08
Wrong! What I am referring to is what the Original Poster wrote since he should know first hand the test conditions and he wrote: Quote:

"Gents,
ISO 13847 is not a construction code it says all about qualification of WPS , NDT, DT as well as production weld.

Test temperature is -31°C
specimen size as per ASTM A370, notch depth 2 mm form the root
Test results of 1 set ( 3 specimens) : 13, 20 & 21 (required is minimum average 41.64, individual 29.64J)
'Cut it' means , he removed the complete weld deposition and rewelded it.

Thanks in advance
nand7400"

This is what I'm referring to Billy! Now would you please go get your eyes checked out already!

Henry
Parent - - By Nanjing Date 12-22-2009 00:56
Henry this is clear to everybody. The issue here is the wire is only tested at -30C with a minimum requirement of 27J when he really needs 42J. And please no more personal messages, I do not read yours.
Parent - - By ssbn727 (*****) Date 12-22-2009 02:25
YEAH RIGHT AND I'VE GOT A BRIDGE FOR SALE REAL CHEAP HERE FOR YOU TO BUY ALSO!!! Don't worry Billy! The folks in here will soon enough find out who you really are if they haven't already, so there's really no need to convince them because you'll do all of that for me - CAPECHE???

Henry
Parent - By Nandesh Kumar (*) Date 12-22-2009 06:45
G_Mens,

Anyway , now I used ER70S-3 for root run and E7018-G , for other passes. Once the tests are over I'll be back with the results...

regards,

Nand7400
Parent - By RonG (****) Date 12-22-2009 13:47
Sorry folks, I just can’t help my self sometimes when another one of my suppressed personality’s (Nanjing) emerge. I try to play nice but I just haven't  got the hang of it yet.
Up Topic Welding Industry / Technical Discussions / CVN test failed!

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