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Old 08-23-2019, 12:17 PM
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LKeithR LKeithR is offline
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Join Date: Aug 2011
Location: Langley, B.C.
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Quote:
Originally Posted by J. Whitton View Post
...A customer brought in some "handmade" wrought chain that they are wanting to use to hang a rather large antique sign. The chain links are made from .250" square stock and are approximately 2.5" long and 1.125" wide. This sign is a little over 100lbs.

Let me fist state that I know very little about wrought iron but I feel this would not be adequate for safely suspending such a large piece. I suggested that we replicate this look with a cold rolled link version. I've always thought of wrought iron chains being too brittle to be nothing more than decorative...
Quote:
Originally Posted by J. Whitton View Post
...Unfortunately the links aren't welded. In my opinion these appear to be mass produced by some automated process...
I think there is some confusion here as to the actual material the chains are made of. True "wrought" iron is an old material that is pretty rare these days. It hasn't been made commercially for some time and I highly doubt that these chains are made from it. It's much more likely that you're dealing with a plain mild steel. The term "wrought iron" is used a lot these days to refer to the process of making ornamental iron products like gates and railings but whether the stuff is hand-forged or not the actual material used is still just mild steel.

The term "cold-rolled" is also sometimes misunderstood--again it refers to a process and not to a material. All steel comes out of the mill in a hot-rolled form. It is the secondary process of "cold-rolling" that produces squares, flats and rounds to a more precise size with a smooth, scale-free finish.

The rolling process also adds a little strength. Probably the most common cold-rolled material in North America is A1018 steel--normal yield strength in hot-rolled form is about 58 kips while cold-rolled material will have a tensile strength of around 64 kips. A fairly popular machining steel is A1040 which in the hot-rolled state will have a tensile strength of about 76 kips; in cold-rolled form the tensile jumps to about 85 kips.

As for strength, if you're hanging a 100 lb. sign using two of those chains (I would presume you're using one on either end) that chain should be more than strong enough. If it makes you feel better you can close up each link with a touch of weld but I don't think it's necessary...
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