brittle fracture CS 516 Gr.70N
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Customer Care
Sep 13, 2020, 10:35:04 PM9/13/20
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Dear Fiends,
I have a question about how excessive heat input affects SAW type welding, in a steel SA 516 Gr. 70 N. That is, a material subjected to Charpy test at -45C, and gave brittle fracture with absorbed energy between 4 to 6 lb-ft.
The WPS / PQR clearly rated, but shop production welding gave these results on pressure vessels.
My certainties indicate that coarse-grained ferrite and widmanstatten ferrite could be formed during the cooling of the weld (highly brittle), and not the expected acicular ferrite, which is the appropriate structure for excellent ductile fracture results in this type of steel.
I open the forum,
Thanks for your attention.
Regards,
Sent from Mail for Windows 10
Ramin Kondori
Sep 17, 2020, 2:25:55 AM9/17/20
to material...@googlegroups.com
Dear Ramon,
Could you share the test results (the lab roport)...?
Has the samples failed in weld metal or HAZ...?
Additionally, please provide us with other test results (tensile test, macro, etc.).
Details are very important here.
Regards
Ramin Kondori
Sr. QA/QC & Welding Engineer
-----------------------------------------------------------
PG-Dip. in Welding Engineering (IWE AT 0070)
BSc. in Civil Engineering (IUT)
BGAS Painting Inspector
ASNT Level I&II
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Customer Care
Sep 18, 2020, 11:20:21 PM9/18/20
to material...@googlegroups.com
Dear Ramin,
I extend the comment on the brittle fracture at -45 C of a SA-516 Gr.70N carbon steel with SAW process, using Flux / wire: F7A6-EM12K.
The findings were:
Manufacture of five pressure vessels, with shell thickness 32 mm /
Destination an Olefins Plant, propane refrigeration section.
By ASME VIII, Div. 1 impact test was required according to UG-84 / Minimum value 20 ft-lb per type of steel.
Charpy test: three 55x10x10 mm samples, absorbed energy was measured at -45C / values of 4-6 ft-lb
Given these out-of-range values, we polished the samples and evaluate in the metallographic microscope: microstructure massive of coarse-grained ferrite and Widmanstatten ferrite was found. Ideally, for reliable service results, the welding forms an acicular ferrite-like structure, for excellent toughness against thermal shock at low temperatures.
The other faces of the fractured samples were observed in the electron microscope-SEM: topography was found with a high cleavage transgranular fracture, typical of a brittle fracture with total absence of dimples and with 60% of charred areas. Burned welding.
Investigating a little more, it was learned that the workshop did use the correct flux-wire combination F7A6-EM12K, and the qualified WPS, but made a mistake: in the night shift work and to speed up the manufacturing, it abused excess heat input, modifying the variables forward speed and voltage on the SAW machine, thereby violating the qualified WPS.
The Licensor, wanted to test in another Laboratory, extracted a longitudinal weld segment. It set up your Charpy tests, with results of 2-3 ft-lbs.
The pressure vessels were repaired on site, to meet quality assurances.
Other remarks:
The quality certificate for SA-516 Gr.70N steel plates indicated Charpy values of 92 ft-lbs., average.
Mr. Pradip, has made his technical observations to this case (LinkedIn), among others the optimal value of heat input for the SAW process in welds with toughness tests, and recommends being attentive to the oxygen levels during the fusion and cooling process of the weld.
I am left with one question: How can a Welding Engineer or Welding Inspector detect or measure oxygen levels in a shop weld and if this variable should be annotated on the WPS qualified?
To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/CAEagfUidzGPHkE%3D%3D4sQKZerN2-q5TqXG-4xsdz5_OinMEo1zNA%40mail.gmail.com.
Ramin Kondori
Sep 20, 2020, 11:37:59 PM9/20/20
to material...@googlegroups.com
Dear Ramon,
Regarding Oxygen level, you cannot measure it in the shop (it's not like GTAW/GMAW) but rather, you have to remove samples from deposited weld and send it to the lab.
It is well established that low oxygen level is essential for better toughness test results (typically less than 300 ppm but should not be too low). Flux composition plays a major role in oxygen contamination and as in steel-making, welding engineers try to lower the Oxygen content. Although using Basicity Index has been criticised by many, using basic fluxes (with Basicity Index > 1) could usually guarantee Oxygen contents of between 200-350 ppm and lead to desirable toughness test results.
But remember, these apply when you have this problem in the weld metal (not in the HAZ).
Many times, high heat input also could create coarse grain regions in HAZ, especially below the cap pass if the voltage is high and the wide cap pass makes the weld cross-section look like a mushroom. I have seen this one so many times. It has nothing to do with the Oxygen level and you will also see very low toughness test results (all because of high Heat Input).
Regards
![IIW-Logo-Colour-small]()
Ramin Kondori
Sr. QA/QC & Welding Engineer
-----------------------------------------------------------
PG-Dip. in Welding Engineering (IWE AT 0070)
BSc. in Civil Engineering (IUT)
BGAS Painting Inspector
ASNT Level I&II
To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/BL0PR03MB4243D7E65F27221BAF10FF4DAA3F0%40BL0PR03MB4243.namprd03.prod.outlook.com.
pgos...@rogers.com
Sep 21, 2020, 4:25:04 PM9/21/20
to material...@googlegroups.com, Customer Care
Hi Ramon,
I’ve attached 2 data sheets FYI. C-51012, is the data sheet of Lincoln
electric for Lincoln 882 flux. The basicity index of this flux is 1.6. Side
by side I’ve attached the data sheet of O.K 10.62 flux, the basicity index
of this flux is 3.4. .
In the past, I had used this flux(10.62) extensively both of Narrow Gap
Sub-Arc process as well as Conventional Double Vee , Tandem SAW of SA 516/70
and other low alloy steels , for impact down up to -45 Deg C. It passed
without any trouble. FYI higher basicity contributes to :-
* Tolerance to higher current
* Is a good scavenger, deoxidant.
Lincoln’ data sheet are excellent. However welding conditions for AWS SFA
5.23 wire flux classification test and ASME Sec-IX qualification tests are
not the same.
In my response I had mentioned about Oxygen level in the weld metal. It’s
difficult to measure in the production shop floor, however good consumable
OEM’s have this data.
Coming back to the problem , I believe the failure is on the Production
Test coupons??. Do you have the welding data of the failed production
welds?
As the failure weld joint has to be cut/ gouged and rewelded. It’s
advisable to shop weld a production coupon, with the existing batch of SAW
Flux & wire , within the amperages , voltage and travel speed as per the
WPS(I mean the Q values) and proceed further once you’re satisfied.
Widmanststten, trans granular these are all secondary things. If the heat
input is out of range (excessive), Charpy Impact is bound to be so low. I
believe , you’ve nailed down some of the observations in your email(as
highlighted).
Thanks.
Pradip Goswami, P.Eng, IWE
Consultant-Welding-Metallurgical Engineering
Cell & Whatsapp-905-9793232.
Personal:pgos...@rogers.com
From: Customer Care <bric...@hotmail.com <mailto:bric...@hotmail.com> >
Sent: September 21, 2020 2:41 PM
To: material...@googlegroups.com
<mailto:material...@googlegroups.com>
Subject: RE: [MW:31483] brittle fracture CS 516 Gr.70N
Dear Ramin,
Excellent answer.
The other thing is, to guarantee high toughness values in a Charpy test on
C-Mn fined grain steel with SAW process, it would be annotate in the
qualified WPS, Notes section, to the Quality Inspector as follow:
1. Get the quality certificate of the flux/wire. Check the base index of
the flux, as indicated in the WPS. Its conservation, free humidity and high
purity.
2. From the production wel bead to the Charpy test, collect samples slag
generated by the process.
3. Along with the specimens machined for the Charpy test deliver the slag
sample to the lab for analisys % oxigen content in the form of oxidation
inclusions.
Also, ultimately, these quality variables can be controlled, but if if the
weld experiment a high input heat excursion, different from qualified WPS;
undoubotable the final structure of the weld ends as coarse grained-ferrite
and widmasttaten ferrite and not in acicular ferrite, and with this,
unfortunate results in the values of absorbed energy.
Look, I started from an indirect case to clarify the brittle fracture
problems in C-Mn fined grains steel, when excellent toughness was expected.
The transgranular high clivaje topography with charred areas revealed the
bad practice of abusing excess high input in the SAW process, as well.
Note: the results of this investigation I lost, and truly, I am sorry.
Regards
Ramon Briceno.
Enviado desde mi smartphone Samsung Galaxy.
-------- Mensaje original --------
De: Ramin Kondori <ramink...@gmail.com <mailto:ramink...@gmail.com> >
Fecha: 2020/09/20 11:37 PM (GMT-04:00)
A: material...@googlegroups.com
<mailto:material...@googlegroups.com>
Asunto: Re: [MW:31483] brittle fracture CS 516 Gr.70N
Dear Ramon,
Regarding Oxygen level, you cannot measure it in the shop (it's not like
GTAW/GMAW) but rather, you have to remove samples from deposited weld and
send it to the lab.
It is well established that low oxygen level is essential for better
toughness test results (typically less than 300 ppm but should not be too
low). Flux composition plays a major role in oxygen contamination and as in
steel-making, welding engineers try to lower the Oxygen content. Although
using Basicity Index has been criticised by many, using basic fluxes (with
Basicity Index > 1) could usually guarantee Oxygen contents of between
200-350 ppm and lead to desirable toughness test results.
But remember, these apply when you have this problem in the weld metal (not
in the HAZ).
Many times, high heat input also could create coarse grain regions in HAZ,
especially below the cap pass if the voltage is high and the wide cap pass
makes the weld cross-section look like a mushroom. I have seen this one so
many times. It has nothing to do with the Oxygen level and you will also see
very low toughness test results (all because of high Heat Input).
Ramon Briceno <http://www.linkedin.com/in/ramon-briceño-976265b5>
Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
Windows 10
From: Ramin Kondori <mailto:ramink...@gmail.com>
Sent: Thursday, September 17, 2020 2:25 AM
To: material...@googlegroups.com
<mailto:material...@googlegroups.com>
Subject: Re: [MW:31463] brittle fracture CS 516 Gr.70N
Dear Ramon,
Could you share the test results (the lab roport)...?
Has the samples failed in weld metal or HAZ...?
Additionally, please provide us with other test results (tensile test,
macro, etc.).
Details are very important here.
Regards
Ramin Kondori
Sr. QA/QC & Welding Engineer
-----------------------------------------------------------
PG-Dip. in Welding Engineering (IWE AT 0070)
BSc. in Civil Engineering (IUT)
BGAS Painting Inspector
ASNT Level I&II
Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
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I’ve attached 2 data sheets FYI. C-51012, is the data sheet of Lincoln
electric for Lincoln 882 flux. The basicity index of this flux is 1.6. Side
by side I’ve attached the data sheet of O.K 10.62 flux, the basicity index
of this flux is 3.4. .
In the past, I had used this flux(10.62) extensively both of Narrow Gap
Sub-Arc process as well as Conventional Double Vee , Tandem SAW of SA 516/70
and other low alloy steels , for impact down up to -45 Deg C. It passed
without any trouble. FYI higher basicity contributes to :-
* Tolerance to higher current
* Is a good scavenger, deoxidant.
Lincoln’ data sheet are excellent. However welding conditions for AWS SFA
5.23 wire flux classification test and ASME Sec-IX qualification tests are
not the same.
In my response I had mentioned about Oxygen level in the weld metal. It’s
difficult to measure in the production shop floor, however good consumable
OEM’s have this data.
Coming back to the problem , I believe the failure is on the Production
Test coupons??. Do you have the welding data of the failed production
welds?
As the failure weld joint has to be cut/ gouged and rewelded. It’s
advisable to shop weld a production coupon, with the existing batch of SAW
Flux & wire , within the amperages , voltage and travel speed as per the
WPS(I mean the Q values) and proceed further once you’re satisfied.
Widmanststten, trans granular these are all secondary things. If the heat
input is out of range (excessive), Charpy Impact is bound to be so low. I
believe , you’ve nailed down some of the observations in your email(as
highlighted).
Thanks.
Pradip Goswami, P.Eng, IWE
Consultant-Welding-Metallurgical Engineering
Cell & Whatsapp-905-9793232.
Personal:pgos...@rogers.com
From: Customer Care <bric...@hotmail.com <mailto:bric...@hotmail.com> >
Sent: September 21, 2020 2:41 PM
To: material...@googlegroups.com
<mailto:material...@googlegroups.com>
Subject: RE: [MW:31483] brittle fracture CS 516 Gr.70N
Dear Ramin,
Excellent answer.
The other thing is, to guarantee high toughness values in a Charpy test on
C-Mn fined grain steel with SAW process, it would be annotate in the
qualified WPS, Notes section, to the Quality Inspector as follow:
1. Get the quality certificate of the flux/wire. Check the base index of
the flux, as indicated in the WPS. Its conservation, free humidity and high
purity.
2. From the production wel bead to the Charpy test, collect samples slag
generated by the process.
3. Along with the specimens machined for the Charpy test deliver the slag
sample to the lab for analisys % oxigen content in the form of oxidation
inclusions.
Also, ultimately, these quality variables can be controlled, but if if the
weld experiment a high input heat excursion, different from qualified WPS;
undoubotable the final structure of the weld ends as coarse grained-ferrite
and widmasttaten ferrite and not in acicular ferrite, and with this,
unfortunate results in the values of absorbed energy.
Look, I started from an indirect case to clarify the brittle fracture
problems in C-Mn fined grains steel, when excellent toughness was expected.
The transgranular high clivaje topography with charred areas revealed the
bad practice of abusing excess high input in the SAW process, as well.
Note: the results of this investigation I lost, and truly, I am sorry.
Regards
Ramon Briceno.
Enviado desde mi smartphone Samsung Galaxy.
-------- Mensaje original --------
De: Ramin Kondori <ramink...@gmail.com <mailto:ramink...@gmail.com> >
Fecha: 2020/09/20 11:37 PM (GMT-04:00)
A: material...@googlegroups.com
<mailto:material...@googlegroups.com>
Asunto: Re: [MW:31483] brittle fracture CS 516 Gr.70N
Dear Ramon,
Regarding Oxygen level, you cannot measure it in the shop (it's not like
GTAW/GMAW) but rather, you have to remove samples from deposited weld and
send it to the lab.
It is well established that low oxygen level is essential for better
toughness test results (typically less than 300 ppm but should not be too
low). Flux composition plays a major role in oxygen contamination and as in
steel-making, welding engineers try to lower the Oxygen content. Although
using Basicity Index has been criticised by many, using basic fluxes (with
Basicity Index > 1) could usually guarantee Oxygen contents of between
200-350 ppm and lead to desirable toughness test results.
But remember, these apply when you have this problem in the weld metal (not
in the HAZ).
Many times, high heat input also could create coarse grain regions in HAZ,
especially below the cap pass if the voltage is high and the wide cap pass
makes the weld cross-section look like a mushroom. I have seen this one so
many times. It has nothing to do with the Oxygen level and you will also see
very low toughness test results (all because of high Heat Input).
Regards
Ramin Kondori
Sr. QA/QC & Welding Engineer
-----------------------------------------------------------
PG-Dip. in Welding Engineering (IWE AT 0070)
BSc. in Civil Engineering (IUT)
BGAS Painting Inspector
ASNT Level I&II
Ramin Kondori
Sr. QA/QC & Welding Engineer
-----------------------------------------------------------
PG-Dip. in Welding Engineering (IWE AT 0070)
BSc. in Civil Engineering (IUT)
BGAS Painting Inspector
ASNT Level I&II
Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
Windows 10
From: Ramin Kondori <mailto:ramink...@gmail.com>
Sent: Thursday, September 17, 2020 2:25 AM
To: material...@googlegroups.com
<mailto:material...@googlegroups.com>
Subject: Re: [MW:31463] brittle fracture CS 516 Gr.70N
Dear Ramon,
Could you share the test results (the lab roport)...?
Has the samples failed in weld metal or HAZ...?
Additionally, please provide us with other test results (tensile test,
macro, etc.).
Details are very important here.
Regards
Ramin Kondori
Sr. QA/QC & Welding Engineer
-----------------------------------------------------------
PG-Dip. in Welding Engineering (IWE AT 0070)
BSc. in Civil Engineering (IUT)
BGAS Painting Inspector
ASNT Level I&II
On Mon, Sep 14, 2020 at 7:04 AM Customer Care <bric...@hotmail.com
<mailto:bric...@hotmail.com> > wrote:
Dear Fiends,
I have a question about how excessive heat input affects SAW type welding,
in a steel SA 516 Gr. 70 N. That is, a material subjected to Charpy test at
-45C, and gave brittle fracture with absorbed energy between 4 to 6 lb-ft.
The WPS / PQR clearly rated, but shop production welding gave these results
on pressure vessels.
My certainties indicate that coarse-grained ferrite and widmanstatten
ferrite could be formed during the cooling of the weld (highly brittle), and
not the expected acicular ferrite, which is the appropriate structure for
excellent ductile fracture results in this type of steel.
I open the forum,
Thanks for your attention.
Regards,
Ramon Briceno <http://www.linkedin.com/in/ramon-briceño-976265b5>
<mailto:bric...@hotmail.com> > wrote:
Dear Fiends,
I have a question about how excessive heat input affects SAW type welding,
in a steel SA 516 Gr. 70 N. That is, a material subjected to Charpy test at
-45C, and gave brittle fracture with absorbed energy between 4 to 6 lb-ft.
The WPS / PQR clearly rated, but shop production welding gave these results
on pressure vessels.
My certainties indicate that coarse-grained ferrite and widmanstatten
ferrite could be formed during the cooling of the weld (highly brittle), and
not the expected acicular ferrite, which is the appropriate structure for
excellent ductile fracture results in this type of steel.
I open the forum,
Thanks for your attention.
Regards,
Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for
Windows 10
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Customer Care
Sep 21, 2020, 11:11:56 PM9/21/20
to material...@googlegroups.com
Dear Ramin,
Excellent answer.
The other thing is, to guarantee high toughness values in a Charpy test on C-Mn fined grain steel with SAW process, it would be annotate in the qualified WPS, Notes section, to the Quality Inspector as follow:
1. Get the quality certificate of the flux/wire. Check the base index of the flux, as indicated in the WPS. Its conservation, free humidity and high purity.
2. From the production wel bead to the Charpy test, collect samples slag generated by the process.
3. Along with the specimens machined for the Charpy test deliver the slag sample to the lab for analisys % oxigen content in the form of oxidation inclusions.
Also, ultimately, these quality variables can be controlled, but if if the weld experiment a high input heat excursion, different from qualified WPS; undoubotable the final structure of the weld ends as coarse grained-ferrite and widmasttaten ferrite and
not in acicular ferrite, and with this, unfortunate results in the values of absorbed energy.
Look, I started from an indirect case to clarify the brittle fracture problems in C-Mn fined grains steel, when excellent toughness was expected.
The transgranular high clivaje topography with charred areas revealed the bad practice of abusing excess high input in the SAW process, as well.
Note: the results of this investigation I lost, and truly, I am sorry.
Regards
Ramon Briceno.
Enviado desde mi smartphone Samsung Galaxy.
-------- Mensaje original --------
De: Ramin Kondori <ramink...@gmail.com>
Fecha: 2020/09/20 11:37 PM (GMT-04:00)
Asunto: Re: [MW:31483] brittle fracture CS 516 Gr.70N
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Kannayeram Gnanapandithan
Sep 22, 2020, 12:01:42 AM9/22/20
to materials-welding
When basicity index increases Toughness value also increase, but weld visual may not be good. Heat input, Interpass are also very critical to get good impact values
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ISO 9712 Level 2 in VT,
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