Copper as an alloying component of steel

G

Guy Thomas

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Feb 1, 2000
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Up until I started reading a metallurgy text I have ("Steel and It's Heat Treatment" by D.K. Bullens) I thought copper was merely an unwanted inclusion, a side effect of the recycling process in the production of steel. I did not think it could alloy with steel at all. This text however lists it as one of the alloying elements of steel and that it can even cause precipitation-hardening under the right conditions.

I would still like to see less copper in the spec sheets when I get my steel but I am somewhat less worried about it's presence now. For some reason I thought copper was immiscible with steel. Any comments on this? What effect, positive or negative, does copper have as an alloying element in a low alloy medium to high carbon content blade steel?
 
Very interesting thread I always thought copper was a bad thing to have in a forge. A mate of mine said it would tend to stop the steel welding. What does the artical say about that true or false.
 
Interesting!

I worked at a large manufacturing company that made cold forgings for the auto industry. We always paid attention to the steel certs as they often hinted as to the ductility of a specific heat.

Several years ago I meet with the metalurgist at Bethlehem's Rod division..(Johnstown wire)who carefully explained that copper undersirably reduces the ductility in steel...which caused cracks in the some of our cold forgings. He explained that copper residuals come from recycled heats rather than Direct Reduced Iron heats. Economic trends in the scrap market determine if steel mills use iron ore or scrap. Periodically the scrap price becomes more econimical than iron ore and thus steel mills flood the market with products that are higher in residuals. After a while, the cycle runs it course and scrap becomes more costly...then the market switches back to DRI. The metalurgist also warned that the residual copper cannot be removed. The reason for the warning was that marginally formable forgings may run OK this year with DRI...but may be very troublesome next year if the scrap market shifts.

Sincerely,
Rob
 
Anything in solid solution can have precipitation hardening efects, some metals or phases are just more effective.

Copper is used in so called weathering steels as a deliberate alloying element to reduce corrosion together with Cr.

TLM
 
The proper term for the effect of copper on steel is 'hot short', that is it tends to be brittle at forging temperature. There are some techniques that minimize the problem but they are not applicable to knife making.
 
The upshot I suppose is that there are some industry applications for alloying copper with steel but as far as blade steels go copper is an unwanted addition whose presence is unavoidable due to the use of recycled steel. My last batch of 1084 had rather high copper content but was apparently within an industry application "acceptable" level for spring steels and I haven't had any noticeable problems with it. Of course I've never had any "cleaner" steel to compare it to either.

Reg, I'm not sure about your question as far as copper contamination. I never made the copper connection but I had heard not to contaminate your forge with brass. That's one reason I'm in the process of building a propane powered furnace for making bronze and casting brass rather than melting small amounts in my blade forge.
 
The reason for not contaminating your forge with brass is the zinc. it has a fairly low melting temp and a low vaporization temp. breathing vaporized zinc is a good way to a quick appointment to the thin fellow with the scythe and black cloak.
 
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