I just lost my response and now I typing it all over again. Curses!
I looked at the photos and have to conclude that the initial weld was deposited with either GMAW or FCAW from the appearance of some of the weld beads. It looks like E7018-H4R was used to facilitate a repair that was unsuccessful.
I disagree with the thought that lamellar tearing is the problem because I would expect the lamellar tear to be in the base plate. From the photos that doesn't appear to be the case. I would expect to see the lamellar tearing to occur adjacent to the HAZ in the base plate and I would expect to see that it is nearly parallel to the surface of the base plate, not in the weld bead as shown in the photograph.
I agree that due to the center-line cracking observed in the photograph, sulfur should be considered. However, the writer states that Lincoln E7018-H4R electrode was used. It looks like the E7018 was used for the repair, but I suspect there is more to this than is being conveyed to us. The Lincoln E7018-H4R (I suspect that it is Lincoln Excalibur electrode) has a relatively high manganese content that should be sufficient to counter any sulfur present in the base metal even if it is on the high side of the sulfur permitted by the ASTM standard. I use that particular electrode when I am repairing steel castings that I know have high sulfur content with good success.
The transverse crack observed in the photograph is a clue that the residual stress in the longitudinal direction are very high. The longitudinal crack in the same photograph is a clue that the transverse residuals stresses are very high. One would expect both to be present in a joint between heavy sections such as is the case with the column and base plate.
I have questions with regards to the actual groove configuration. The writer says they are "double V bevels", which I suspect are bevel grooves, but because the writer is not using standard AWS terminology, it causes me to make some educated guesses as to what he really means. What I don't know is whether the column flanges are beveled on one side, i.e., the outer surface of the flange where the welder can weld the full length of the joint without interruption, or if the flanges are double bevels so the flanges are beveled on the outside face and the inside face of each flange. The welder would be able to weld the outer face without interruption, but the inner surface would be interrupted by the column web and would necessitate an access hole through the web to make the weld continuous. The later case isn't typical in my experience. Then there is the issue of whether the flange welds are complete joint penetration groove welds or partial joint penetration groove welds. We don't know!
The writer says the welds cracked after the "second filler". Sorry, but I have no idea what that means. Assuming the grooves were double bevels, i.e., there was a bevel groove on both the outer face and inner surface of each flange, does he mean that the weld cracked after the first side was welded to completion and the second groove weld was started? If the weld detail consisted of single bevel grooves on both flanges, does he mean that the weld in the second flange to be welded cracked after the first flange was welded to completion? Again, I can't tell from the details provided.
With the limited details provided, I still believe the high restraint that resulted from fitting the base plate tight up against the end of the column shaft is the culprit. I believe the placement of soft steel wire between the end of the column shaft and the base plate provides a means of accommodating the contraction of the cooling welds and minimizes the resulting stress to prevent the longitudinal crack from initiating.
As I stated previously in this response, I don't believe we are being told the entire story. We are being fed information bit by bit. I waiting for "Paul Harvey" to say, "Now for the rest of the story". Wouldn't it be refreshing if we had all the details up front so we would have to guess what the real situation is?
I've attached a sketch of the weld detail I think the writer is trying to describe. I would like to know if the sketch is close to what the real weld detail looks like of if the joint looks different. I would also like to know what process and electrode material the initial weld was deposited with. Based on the photographs, I assume the initial weld cracked and then the repair that was attempted cracked. Tell us the whole story, not bits and pieces.
Best regards - Al
Hello Al, I just recently looked through this post. One of the pictures of the cracking that is present here reminds me of conditions that are present when the pieces to be joined are beveled and then gapped or not, prior to welding. The initial welding from one side exhibits inconsistent levels of fusion through the joint for whatever reason. Yet, when the welding is performed from the other side, possibly the root hasn't been prepared properly(back-gouged or ground to clean out all traces of incomplete fusion or excessive or incomplete fusion) before welding from the second side has taken place. This tends to allow cracking to appear in line with the groove as well as transverse to it as levels of fusion aren't consistent and can appear in various directions. Not very scientific, but a condition that I have noted through experiencing similar types of things over the course of my career. Just a bit of additional food for thought. Best regards, Allan
Hello Allen;
Do all the weld passes appear to be SMAW to you or am I missing something?
Best regards - Al
Hello Al, to me it looks as though the welds have been excavated with a carbon arc and sand blasted as well so I couldn't really tell which process has been used. The quality of the photographs make it really difficult to see much detail as well. After looking at these again I believe my first assessment of these is likely wrong, I thought that I was looking at a condition which was much further inside the joint. I wonder what an analysis of these base materials would yield in the way of carbon content and other elements? I also wonder about the machine parameters if in fact much of this was done with FCAW gas-shielded? I cannot think of any sort of issues that could occur with the use of SMAW and show up like this. On the other hand, if it has been done with FCAW gas-shielded I do believe that excessively low voltages might yield a condition that could cause something along these lines possibly. That's just my take Al and as you stated: Paul Harvey would probably say "and that's the rest of the story". So I'm sure we'll all need to get a bit more information before this one unravels. Have a great day, Allan
fcaw repaired with smaw is known to potentially cause welding issues, diluting the AL. causing a more brittle deposited weld.
Hello Hogan, some time ago on another thread I mentioned that back during my schooling days my instructors had said that it was okay to apply E7018 filler over E6010 filler, but not the other way around. At that same time I asked the question about other combinations such as this that could potentially cause issues. Apparently you may have missed that one or not yet been a participant on the site, I would have appreciated your input. I do now. That is an interesting point as there are numerous instances where field mechanics and others who are responsible for the repair of heavy equipment and other products would likely face this sort of scenario quite often. Manufacture: FCAW gas-shielded, Repair: SMAW or FCAW self-shielded in many instances. Do you have any more information on this topic? Thanks and regards, Allan
Hello Hogan and Allen;
I've encounters cleaning difficulties with using FCAW over SMAW tack welds. I haven't encountered problems welding with low hydrogen over FCAW, but I have to imagine it is dependent on the specific FCAW electrode that was used to weld the joint initially.
Allen, I think you and I agree that that it doesn't appear that the entire weld was deposited with SMAW electrode.
Where's Paul when you need him?
Best regards - Al
Some of the welds were done with FCAW , This procedure failed ,then was arc gouged out and cleaned . The second procedure was smaw 7018 h4r 1/8 . The results was the same (Failed UT ) cracks in welds. WE have arc gouged and cleaned several times. We have 10 flanges to weld , 5 of the flange welds are single bevel with full penatration w/a 1 1/2" thick flg. we welded all smaw w/ 7018 h4r . All passed UT, the other 5 were 2 1/2" thick with a double v bevel w full penatration (>I ) The thicker weldes are the ones that seem to be given us problems. Over the weekend we have managed to get one to hold and pass UT. The procedure we used was a post weld heat treatment (Resistance Heat Treatment ) we controled the cooling rate for three hrs. This seem to work for us. Now if this solves the problem with the rest of the welds we will be happy. IM not convinced that the isues were the welding procedure or the processes. But just the material being welded . I dont think we should of needed to do a PHWT on A 572. Thanks for the input and not being too tuff on me for my lack of techanical comunication skills. Im still learning this side of the biz .
do you perform MT on the excavations?
Hello Roadhand, one small additional point of interest for you to consider. In many cases the thickness of a particular plate, regardless of it's grade, will necessitate altering the chemical content of the specific material. If you have 1/4" A-572 and 2 1/2" A-572, an analysis of these two plates may be different even though they are both identified as "A-572". The reason for this difference is due to the difference in cooling rates upon completion of the manufacturing process. Because the thicker plate cools more slowly it would likely end up being "soft"(think in terms of annealing) when compared to the thinner material, thus chemical alterations and additions are done to allow for this slow cool in order to maintain the tensiles, yields, and other properties for this specific grade. It is possible that these differences could be a part of the problem you are experiencing with cracking and be the reason why the PWHT has been able to prevent this in some cases. A little bit more to consider. Best regards, Allan
Aevald, this is what i came up with on a quick search of FEMA 353, and it's predecessor FEMA 267 (interim guidelines)
Fema 267
Except to the extent that one requires Charpy V-Notch toughness and
minimum yield strength, the filler metal classification is typically selected by the
Fabricator. Compatibility between different filler metals must be confirmed by
the Fabricator, particularly when SMAW and FCAW-SS processes are mixed.
Generally speaking, SMAW-type filler metals may not be applied to FCAW-SS
type filler metals (e.g. when a weld has been partially removed) while FCAW-type
filler metals may be applied to SMAW-type filler metals. This recommendation
considers the use of aluminum as a killing agent in FCAW-SS electrodes that can
be incorporated into the SMAW filler metal with a reduction in impact toughness
properties.
this wording is not in FEMA 353. the closest I coud find was :
Fema 353
3.3.2 Intermix of Filler Metals
For welded joints requiring CVN toughness in Seismic Weld Demand Categories A and B , when FCAW-S filler metals will be used in combination with filler metals for other processes, including FCAW-G, supplemental toughness testing shall be conducted as prescribed in Appendix C.
hope it helps.
Hello hogan, I believe that is very good information to know and should be considered by many when working as we do. Thanks for including that. Best regards, Allan
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