Hot or cold?

[Gerry Slater]

What’s easier to forge-weld, hot rolled mild steel or cold rolled mild steel? Thanks.

[Steve Sells]

there is no difference, did it seem there was one when you tried?

[pnut]

Just how much it costs at the steelyard. Hot rolled is cheaper and if you're going to put It In a forge there's no point in buying cold rolled.

Pnut

[George N. M.]

The only difference between hot and cold rolled steel is how crisp the edges are and how smooth the flats are.  Cold rolled has sharper corners and smoother flats and is usually more expensive for the same size as hot rolled.  There is no difference in the metal.  There should be no difference in forge welding as long as you have prepared your welding faces properly.

"By hammer and hand all arts do stand."

[Frosty]

Cold rolled is ground to much closer tolerances after a finish cold rolling which increases work hardening. Cold rolled is harder as it comes and an exact dimension. IF you put cold rolled in a forge it's lost the properties you pay extra for before it reaches red heat. 

By analysis they're close enough to the same as to make no difference.

Frosty The Lucky.

[Kozzy]

There is often also a scale issue between the two.  Though the metal is the same, the processing on HRS can leave scale that must be removed.  CRS is descaled before rolling to size.  For the average smith, the process of forging is re-scaling to some extent so it's generally not worth the extra expense for CRS unless you are forge welding the factory surfaces (which should be cleaned anyway before welding)

In the last year or so, I've done some work with 2 different major steel mills who were trying some new wild ideas for descaling.  Apparently descaling is one of their biggest frustrations and adds quite a bit of cost so they are willing to throw money at just about any possibility which may have some merit.  The old chain flail systems just aren't cutting it for them.

[Judson Yaggy]

I must respectfully disagree with the consensus.  At my steel yard hot rolled (hr) is A36.  Cold rolled (cr) is still 1018, or so they claim.   Slightly different chemistry, and cr forges somewhat more easily.    I'm not far from the border with Canada and most of our steel is still imported from there despite the tarrifs so this may be a regional thing.  It will also forgeweld easier becasuse of the cleanliness of the surface (no mill scale).  A pile of hr widgets stacked up in the gas forge for texturing stay seperate pieces, while the same widgets of cr will start sticking to each other after a while, unintentional forge welds.  Intentional forge welds may be acomplished at lower temps with cr as long as it's the material's first pass thru the forge.  

May be splitting hairs here, I buy hr whenever possible due to the lower price as noted above.  But some sections, especialy sheet, plate, and small bar are more common in cr, and it welds very well.  Just my observations from forging every day.  

Kozzy, descaled hot rolled available commercially would be great!  Please keep us in the loop!

[Frosty]

No you're not splitting hairs Judson, you're absolutely right. Unless you specify 1018 or mild, most hot rolled on the rack will be A 36 and a less consistent consistent/precise analysis. 

Seemingly small details like this can make a big difference if they catch you unawares.

Frosty The Lucky.

[pnut]

A-36 is a performance specification while 1018 is an alloy isn't it? The place I buy steel offer hot rolled 1018 all the way up to 1080 in square and round. Guess I'm lucky although the smaller sizes in 1018 is more likely to be out of stock. At any of the big box stores the "weldable" or mild steel they sell hot or cold rolled I would assume is A-36 unless otherwise marked.

 

Pnut

[anvil]

Ive always been under the impression that hot rolled and cold rolled are the same A36. First its hot rolled to a close tolerance, then cold rolled to a closer tolerance. An extra step and a closer tolerance equals a higher cost.  Ive never checked specs at the steel yard. 

I wonder if some 1018 comes cold rolled? Im pretty sure that 1/4" key stock etc is cold rolled and thus work hardened A36. Intuitively id guess 1018 might not have enough carbon to work harden. Fair warned, thats totally an assumption.

[Ted Ewert]

One thing I've come across with HR is inconsistency in the hardness. Every now and then I'll hit a hard spot while drilling through a piece. I assume this is a piece of recycled alloy which got in the mix and didn't blend well. Doesn't say a lot for the quality control, although in most applications it wouldn't matter. 

[ThomasPowers]

I ditto the warning the "mild" is NOT a specification it could be anything below 30 points carbon and these days you generally get A36 when you ask for mild UNLESS you specify 1018 or 1020 or... and are willing to pay extra for the alloy.

It used to be that hot rolled was generally A36 and cold rolled was generally 1018 or 1020; but they are cold rolling A36 now I have been informed as cheapness trumps quality these days.

[anvil]

https://www.industrialmetalsupply.com/blog/difference-between-hot-rolled-and-cold-rolled-steel/

Heres the process. 

 

[SLAG]

Anvil,

A great reference.

Thank you for sharing it.

SLAG.