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Home Model Engine Machinist > The Tools and Tips > Metals > REEBAR-cheap source of High Tensile Steel

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Old 03-22-2016, 07:34 AM   #1
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Default REEBAR-cheap source of High Tensile Steel

As an apprentice in the UK in the 60s there were many grades of steel,many of which I was familiar with mainly mild steel or En2.Now in Australia the only 2 I know are 1214 free machining, or 1020 for welding.I don't know much about tensile strengths.Everything else for me is hot rolled.My main ref with what I am familiar with is grade of bolts. 4.6 = mild steel ?. 8.8 = high tensile
and cap screws 10.9 to 12.9
I saw a video on utube about machining rebar which I believe comes in 3 grades and would be classed as high tensile.A cheap supply of ht or very tough steel.Reebar is subject to strict quality control (it holds skyscrapers up)
The video shows making a special high tensile bolt from rebar with machining
very easy with rct.At the other exteme I saw a video of a contractor hiiting a piece of cheap imported rebar against concrete and it breaking.Poor quality very brittle.I assume a death trap
When a house was being built on the block next door I scrounged some pieces of rebar for possible use.I started with a 10" piece of nom 30dia and machined
to the most economical section. 22mm a/f octagonal just as an excersize
It machined well with good finish.I don't know the grade would call it high tensile,a good source of tough steel for pins,nuts and bolts etc.Any input
by others on the tensile strength of steels and differing names would be most welcome.The steel does ring when struck and is much tougher to file so
lets just call it High Tensile


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Old 03-22-2016, 08:24 AM   #2
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Very nicely discovered Baz.

As you may know, I tend to make things from dontknowwhatium, but have never even thought of or tried rebar. I will get a bit and try it out.

John


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Old 03-22-2016, 12:20 PM   #3
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I experimented with turning some rebar a few months ago. The surface finish I got wasn't great, but the price for rebar is cheap. From .5" rebar I got some .4" round once the extrusions were cut down.
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Old 03-22-2016, 12:45 PM   #4
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Yes machining the surface is labour intensive but I think worth the effort
I wouldn't buy it,its usually lying around near building sites hence very cheap
I walked round a new house build next door and picked up offcuts
nom 30mm dia total length about 1.5m and 20dia as much as wanted
Didn't get too much as I was unsure if I would ever use it,keep an eye on this thread I plan to machine up some hex.I can only say that the finish was far superior than with HRS and that was just rougth milling,i am going to try lighter finishing cuts etc with the next trial
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Old 03-22-2016, 04:50 PM   #5
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Here in America rebar can be made of anything. I have personally cut a piece on a chop saw and have seen 2 different materials in it. A dark layer was clearly evident, the metal was not mixed very well. I still would use it but would be careful with safety in mind, not that I make rocket parts or use them for brain surgery.
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Old 03-22-2016, 06:33 PM   #6
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Letting it sit outside for a few years won't do it any harm.

I don't think rebar is stockpiled as such, but basically comes straight from the manufacturers to distributors as and when needed (for large projects of course). So it will be full of all sorts of stresses.

As I have said before, all my ferrous stands out in the weather but under cover. Some of it has been outside for 20 years, and what is still bright and shiny I class as stainless, but I can tell you one thing, materials do cut a lot differently when weathered for a long period, much easier to cut with better finishes, especially cast iron, my sash weights come up like chrome, mind you, they are most probably well over a 100 years old before I get them.

Time to put a few bits into storage.

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Old 03-22-2016, 07:37 PM   #7
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I used to work where we cut threads on anywhere from #4 to #12 rebar. They're what holds the ceiling up in the Washington D.C. metro. I bet we made at least 500 tons of that junk. Very inconsistent material. Chasers would last all day on some and only 100 pieces on others.
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Old 03-22-2016, 10:21 PM   #8
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our thoughts on quality are same as mine.I assumes tight quality control
on one hand as the r,bars are calculated by structural engineers for building skyscrapers and bridges etc.Some are prestressed before encasement
On the other hand how critical is the quality if encased inconcrete.Go figure
Any comments from more knowledgeable people would be welcome
The first piece I tried however machined well with excerlent finish.From
experience I would say good quality HT steel and its free,just the stuff to keep in reserve for special jobs
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Old 03-23-2016, 08:37 AM   #9
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Rebar is not "high quality" steel , for the most part it is just cheap hot rolled mild steel. Source is the important factor.
In many third world countries it is made by re-rolling scrap steel from construction or ship breaking and there is very little control over content.
However as most of the scrap comes from the west , including redundant war ships there is no reason for the material to be inferior but I have often found laminations and spalling when machining.
Some foundries in the UK , unfortunately mostly gone now , would not buy re-bar scrap because of undetermined quality.
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Old 03-23-2016, 10:59 PM   #10
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China and India supply cheap matls and like everything else are cheap and poor quality.However for the western world there are stds for rebar and specifications and certifications,so to my mind good quality as would be required for building bridges etc.I googled and got plenty of info.There are 3 grades 30, to 50 tensile strength so some rebar must be good quality
in order for structural engineers to design reinforced concrete beams etc
Therefore to my mind not all bad.I seem to be lucky and have good stuff not foreign.Will keep you posted


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