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1000 and 1100 series steel


Dunlop Slayer
NAXJA Member
New Jersey
Got a project where I need to repair and strengthen a load bearing backing plate assembly fabricated with several pieces of 1000 and 1100 series steel.

Couple of questions if you happen to be familiar with and have worked with the stuff:

Can I MIG weld it, single and multipass? If so, recommended wire and gas?
Are there other steels that can be welded to it with a compatible wire? If so, what steel type and wire type?
Anything odd versus mode common steel types that I should be aware of?


Those are both unfinished terms, the rest of the designators are more important to the exact properties and needed to answer your question!
The steel was also categorized as "low alloy steel". I have some analysis sheets that I can add for more info if that would help.

The last 2 #'s are the critical ones designating the carbon content. They are both low alloy steels but the higher the carbon content the harder the steel gets. As that happens the welds are more susceptible to cracking. You didn't say whether they are cast, but pre-heating and slow controlled cooling help in these situations.

The shop I went to could not get an exact match on the type, just on the family. I guess I need to find a good reference and try and find a match. Carbon content was one data point they could not obtain. Here's a few of the reports for the various pieces of the assembly:

#1 - 1000 Series LAS
Element %
S 0.040
Cr 0.100
Mn 0.414
Fe 99.172
Si 0.232
Ti 0.019
V 0.010
Ni 0.020
Cu 0.030

#2 - 1000 Series LAS
Element %
Cr 0.074
Mn 0.378
Fe 99.351
Si 0.124
Ti 0.010
V 0.002
Ni 0.021
Cu 0.040

#3 - 1100 Series LAS
Element %
S 0.060
Cr 0.063
Mn 0.366
Fe 99.201
Si 0.254
Ti 0.013
V 0.005
Ni 0.020
Cu 0.019

#4 - 1100 Series LAS
Element %
P 0.039
S 0.092
Cr 0.049
Mn 0.939
Fe 98.288
Al 0.287
Si 0.223
Ti 0.022
Ni 0.026
Cu 0.035

Every piece of the assembly appears to be plate of various thicknesses from 3/8" to 7/8".

Tell us what your working on, take pics of the pieces.
Just want to comment that 1xxx series and 11xx series are categorized as carbon steels, not LAS. The term LAS is somewhat misleading. Such steels have small, but not insignificant amounts of selected alloying elements such as Cr, Ni, Mo, higher Mn.

It looks like the 10xx and 11xx categorizations are being selected based on indicated sulfur content. The higher sulfur improves machinability. If the pieces tentatively labeled as 11xx series steel have significant machining features, then it would make sense for those pieces to be from that series of steel. If those pieces have no significant machining features, then my guess would be that they could be all the same steel.

If this is a critical structure, then you may want to have OES performed on samples of the pieces to measure carbon content. I think that there a places that can do this for something like $50/specimen.

If its not a critical structure, then perhaps you can perform some trial welds on the pieces to determine weldability parameters.
Yes, I mis-spoke.......

Plain carbon steels are classified into four distinct series in accordance with the AISI system:

The 1000 series are plain-carbon steels containing no more than 1.00% manganese
The 1100 series are resulfurized (sulfur is added) carbon steels for machinability
The 1200 series are resulfurized and rephosphorized for machinability
The 1500 series have between 1.00 and 1.65% manganese
RCP and Max,

Thanks for additional questions and info thus far.

Until I can get access to the place I usual upload photos to for NAXJA, the ones I attached to this post are the best I can do.

Hopefully you can see where the 2 sections of this assembly have been cut apart. This was the only location that it was welded together and was flexing just enough to cause worry and start to cause problems. The plan as it stands now is to add gussets on either side to re-enforce this joint. The other modification is to remove the thinner extension on the other end and replace it with a slightly larger one in order to have a larger platform for the mount that sits atop it.

As to what this franken-bracket is: It is the backing plate for a keel on a sailboat. There are 3, 1.5" threaded rods that come though the 3 holes seen from above. 3, 2.25" nuts are used for fastening.

When I can get the higher res photos uploaded, you'll be able to see more detail.



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If someone used one of those chemistry guns to get the composition, I would guess that the samples with the higher sulfur values are from contamination. A high sulfur steel is not a good choice for marine applications.