What type of steel is this?
What type of steel is this?
(OP)
I've got a building built in 1993 that was built using (reportedly) recycled bridge steel (don't know when the bridge was built). We are doing a remodel and are having some trouble welding to the existing wide-flange beams (cracks have been visibly detected at all of the welds so far). I had them sample a couple of the flanges to have a chemical analysis done so we could try to determine exactly what type of steel we have and develop and weld procedure. It's a 3-story building and samples were taken from the bottom flanges of random beams at each level. After the analysis, the testing firm reported that there were actually two types of steel being used, 1018 and 1020 steel. Attached are the test results.
As you can see, there are a couple of other chemicals floating around in the steel sample as well. The testing firm, who is also acting as the CWI, tried a test weld by preheating the sample to 225 degrees F at approx 3" from the weld. During their bend test after welding, the sample cracked and broke in the preheated portion of the sample, not at the weld, and at not much of a bend angle either (see pic).
Are these results indicative of 1018 or 1020 steel? Has it been carburized and that's what is causing the welding difficulty and extra chemicals? My main issue is developing a weld procedure for the old steel. So far the testing firm has tried preheating and welding with a flux-core wire feed.
Any ideas?
As you can see, there are a couple of other chemicals floating around in the steel sample as well. The testing firm, who is also acting as the CWI, tried a test weld by preheating the sample to 225 degrees F at approx 3" from the weld. During their bend test after welding, the sample cracked and broke in the preheated portion of the sample, not at the weld, and at not much of a bend angle either (see pic).
Are these results indicative of 1018 or 1020 steel? Has it been carburized and that's what is causing the welding difficulty and extra chemicals? My main issue is developing a weld procedure for the old steel. So far the testing firm has tried preheating and welding with a flux-core wire feed.
Any ideas?





RE: What type of steel is this?
The Silicon content is interesting. It is normally in the 0.15-0.35% range, unless purposely kept low. It is usually kept low for weldability reasons, so this is not the issue, but it is interesting.
What is not reported in the levels of Vanadium (V), Titanium (Ti), Boron (B), or Columbium/Niobium (Cb/Nb--these are just different names for the same element). These are often used for added strength and their presence in the 0.03% level or higher could cause trouble (0.0005 for Boron). Just taking a wild guess, this is what you are dealing with.
rp
RE: What type of steel is this?
RE: What type of steel is this?
Redpicker, would Vanadium, Titanium etc normally be tested for in a chemical analysis or do you have to specifically test for each one?
Jwhit, I thought preheating the weld was in part to drive off any residual gases. Is this not the case? Also, I'm not familiar with aluminum nitride; why would it be present?
I should also tell you that the Rockwell B hardness tests for the two materials came back ranging from 70-83. Do you think we are still dealing with 1018 or 1020 steel? I've never heard of it being used for w-flange beams before.
RE: What type of steel is this?
RE: What type of steel is this?
RE: What type of steel is this?
RE: What type of steel is this?
As far as a plan of attack for getting a good weld on this, what would you recommend? Do we need the additional testing (Al, V and Nb) to figure this out?
I really appreciate your help, guys.
RE: What type of steel is this?
RE: What type of steel is this?
RE: What type of steel is this?
RE: What type of steel is this?
two things: I understand this means the bridge steel was taken down and rebuilt, NOT re-melted into new shapes, right?
If so, is there surface contamination and residuals on the weld areas (old salt, paint, oil/grease/tire rubber/atmospheric "gunk" maybe) that is fouling up your surface before and during welding? If you are grinding clean the weld areas, how "clean" are they, and how deep is the grinding "on average" and "in actual practice"? Just "shiny" may leave lost chemicals on the surface, smearing them into the metal pores.
RE: What type of steel is this?
The steel all had lead paint on it that was removed by sand/water blasting. I'm not sure that they have done any grinding to try and clean the surface. I'll check and see.
RE: What type of steel is this?
Of historical note: A36 was first published in 1960 and replaced ASTM A7, which was structural steel used for bridges and building. A7 may be your applicable spec depending on bridge age.
RE: What type of steel is this?
This building was built in 1993, so there won't be a possibility of any heat treating. No existing cracks in the steel have been found. Unfortunately, we have no idea when the steel was originally put into use.
RE: What type of steel is this?
Let me know where that building is so I can put it on my list of structures never to enter.
"If you don't have time to do the job right the first time, when are you going to find time to repair it?"
RE: What type of steel is this?
RE: What type of steel is this?
Hmmmn.
If a significant lead layer were still present after waterblasting - because I know shotblasting if done poorly will only drive paint articles deeper into the pores and scratches in old steel - would that lead screw up the welds towards the breakage you see? .. I've never gotten a satisfactory weld (GTAW especially) on old painted surfaces until they were ground "bright clean" (rough is OK, but they have to be clear metal. Whenever possible, even after paint removal, I specify a qualified SMAW (stick) weld because the greater heat burns through better.
Obviously, not all of the welds broke off. Is there any pattern to which ones broke and which ones were good... so far good, that is?
RE: What type of steel is this?
RE: What type of steel is this?
RE: What type of steel is this?
RE: What type of steel is this?
i feel that you could probably monkey with the weld geometry to prevent the weld from pulling across the rolling direction to prevent the suspect laminations from giving away.
surface preparation before welding (light grinding, wire wheeling) to remove oxides, dirt and other crap, and prep the joint for welding is key. if surface preparation is the issue, also check holding oven temperatures for low hydrogen stick electrodes (7018). if they're out of the oven four hours they're no good.
RE: What type of steel is this?
RE: What type of steel is this?
RE: What type of steel is this?
Are you saying flux cored welding shouldn't be used for this type of welding, or you wouldn't use it knowing what we know now after all of the testing we did? The GC is going to ask for more time/money because he said he bid the job for wire feed welding. I don't want to screw him over, I would just like some input on whether wire feed should have ever been considered, and what's the actual time difference we are looking at.
For any of you still following, the MP test on the root weld and the final weld both passed and the SI is going to do a VI after 48 hours as well. The ended up grinding the surface of the steel and using E7018 electrodes. Thanks for all of your help on this one.
RE: What type of steel is this?
RE: What type of steel is this?
RE: What type of steel is this?
RE: What type of steel is this?
Figure a 7:00 am "payday start. If on a bridge scaffolding or deck, "maybe" 8:30 when the first rod is struck.
RE: What type of steel is this?
RE: What type of steel is this?
They started with FCAW and the welds were visibly cracked. So, they took a couple of coupons, welded them up using the same process (but they preheated this time) and the welds failed the bend test. So, now I've had them grind the existing weld surface clean and weld the tubes up with low hydrogen SMAW. This way passed the MP tests and the VI. Now the GC is asking for more money because he said he bid FCAW and SMAW is going to take a lot longer. Our specs say weld per AWS D1.1 AND use E70 low hydrogen electrodes so I think we are covered on that.
Does anyone know if the procedure for FCAW overhead is prequalified? I didn't think it was.
RE: What type of steel is this?