Instructables

ReBar!

I happened to find a 20' length of 1/2" ReBar in the woods behind my house (I have magical woods, i also found a 3' length of I-beam I use as an anvil). What kind of carbon content does it have (I imagine not terribly high) and would it be at all useful for making blades, or reserved for making tongs and trinkets (later down the road I'm going to make a caduceus) and the like.

i just made my first knife not too long ago, i use lump charcoal,great for blacksmithing, and i found out that it only takes you one time, the first hopefully, before you get the knack. needless to say, it didn't turn out how i wanted, but the next one was perfect. the third is coming soon, half way done, and it's doing great. all out of rebar. rebar has semi-low carbon content, good for blades if you aren't putting serious, and i mean quite a bit of stress, on the blade. for anything else like tongs it's perfect! as for a caduceus...sure. don't burn yourself.
th30be1 year ago
Would you have to heat it up or could you just hammer it down with out any type of heat source?
Your not going to be able to hammer out a blade from a cold piece of rebar. Well i guess you could with enough force but you won't be able to produce that force on your own.

Your better of getting the metal red hot before hammering on it to change its shape and composition. Besides forging the metal helps to increase its strength and durability. Its actually the rapid cooling of the metal that hardens it allowing it to hold an edge. A cold hammered knife wouldn't not hold an edge as well.
Alright. Fair enough. I made a charcoal foundry for casting aluminum. Would that give off enough heat to head up the rebar?
Should work if you keep a good and constant airflow in it. You just need to get the bar red hot so its soft enough to hammer on. Once you start working it you gotta keep working it or keep it in the fire. Don't let it cool and don't squelch (quickly dunk it in a bucket of water) it till your done. When you are done then get it good and hot then squelch it. This will help harden the steel.
I have made 3 knives from domestic rebar, 2 were the sharpest knives i've done and the other I scraped because I did not like the design and over ground it. I acid etched the utility knife I made myself and you can see varying patterns like ertched pure iron has but the knife is razor sharp and hardened very well. the other blades had no variations after etching so it might be a good technique to forge your blank to the thickness and shape grind it clean and acid etch to see how much variation there is. I use alot of 1018 to make Iron Age style weapons and it hardenes suprisingly well and wont shatter or break. I recently forged a knife from a steel ring inside of a sement ring and tempered, its sharp as a razor and very easy to re sharpen, its close to Iron Age steel and works very well. Experimenting is the fun part. Hope this helps.
DeusXMachina (author)  norseblacksmith5 years ago
That's really cool. I'm glad I know that now.
lgtwood5 years ago
I'm a newbie here, and I don't know anything about making things from steel, but I do work in a steel mill. The "melts" are called heats and each one is specifically tailored for the product being made. The steel is actually stirred to create consistency before it is cast into billets which are re-heated and rolled into finished product. The chemistry is consistent throughout the heat(about 100 tons). We make 4 grades A706(softest) ,40, 60 and 75.The profile of screws might have happened decades ago, but are impossible these days since our arc furnace works at around 4000 degrees if I remember correctly. Try new rebar from bridge projects or highrise buildings. These sometimes use grade 75. Hope this helps.
OrionBlade5 years ago
I've used rebar to make chisels, knives, and even a punch or two and a screwdriver in a pinch. It doesn't do well as a hot cut chisel, but once sharpened, A friend used a chisel I made for over six months cutting pockets in door jambs and hadn't sharpened it, looked brand new. The knives work great, and I have a pruning knife that I use to cut 1/2 inch diameter branches or smaller, and it's kept an edge quite well with only minor stropping - no re-grinding or anything ridiculous. Modern rebar is fairly consistent even though it's the "dregs" of a melt - once the steel is melted, the carbon/alloy content is fairly continuous throughout the melt. You will not find profiles of screws and the like as some mythology holds. From piece to piece you will find some variance in carbon content, etc. - but in one continuous bar, you're likely to be able to heat treat as though it was W-1 - just be sure you normalize before a quench and you should be fine.
The carbon content in rebar can vary wildly from one spot in a rod to another. You might be lucky enough to hit a uniform patch, but there's always danger of some high sulfur or high phosphorous or just way high carbon section causing cracking at the quench or during use.
Have you seen such things happen? It sounds like one of those legends spread by dealers in more expensive metal. I mean, rebar has got to be mass produced from huge batches of (molten?) steel; how it is supposed to have acquired these wildly varying sections?
I don't know for sure why those sections exist, but I guess the steel isn't kept liquid long enough to be fully homogenized (there's no need for perfect uniformity in rebar, as it'll just be normalized before use, which prevents most heat treating hiccups). I've been unlucky enough to experience rebar's variabilty. I made several j-hooks out of the same rebar stock and quenched them all as I thought they were mild steel. Four did fine. One shattered in the water. The last one split all to pieces when I drew it out.
abbabibble26 years ago
I just found that some grade 60 rebar is rather good for blades, resulting in pieces like this and this
Vendigroth6 years ago
Rebar's usually made of the last dregs of a steel melt, so y ou can never be really sure what's in it. I don't think it's the best stuff for blades, because one blade could be excellent and the next absolutely crap. Personally, I'd save it for non-hardened stuff
Goodhart6 years ago
In the United States, rebar comes in two grades of carbon content, Grade 60 and Grade 40. Grade 60 has a higher carbon content and, therefore, a higher tensile strength, but its stiffness can make it difficult to bend and cut. Construction workers always prefer to use Grade 40 rebar.
Raevun686 years ago
I have used rebar for blades in the past myself. I found an article once on the web (can not remember where) that stated the an easy way to tell how high the carbon content is by looking at the criss crossing marks on the outside of the rebar. You will notice that the rebar will have casting lines on the outside of the rebar. According to this article the more criss crossing lines indicates a higher carbon content. I found some scraps at a construction site near my home at that time and found that these pieces had a lot of criss crossing marks. So I figured I would give it a shot. The metal worked nicely and it was not too bad to forge, the one thing I did find to be a hassle was the rust factor. I became ill and was in the hospital for a while and my garage had a pretty bad draft and the moisture in the air did cause some rust, but I am sure if I had stored the blade blanks I made, the rust factor would not have been an issue. Also as stated above you can always test the rebar with the spark test or you could try to find a local supplier of rebar and see if there is any way to tell by looking at the rebar what kind of carbon content it has. I hope this helps with your question.
NachoMahma7 years ago
. I really don't know much about this, but no one else has answered so here goes. . I've seen magazine articles that show how to use the sparks produced by a grinding wheel to approximate the carbon content of metal. IIRC, smaller sparks that "finger" indicate more carbon. All the rebar I've seen appears to be pretty soft, so I'll guess it doesn't have a lot of carbon. . Just about any steel, if properly forged/hardened/tempered, should be able to make a good knife of some sort. Depends on what the knife is to be used for. . With 20' to play with, experiment! If you end up with a crappy knife, start making trinkets. :)