Quenching hot steel

[La gib]

Hi guys

I am new to all this and have recently acquired the tools needed to really have a go.
I have made a few items and only last week completed some metal work to fit to a mirror that I made.

My question is a beginner’s question. I have read some info regarding hardening and tempering but it goes in and out again so will have to take a bit at a time.

So, when forging some mild steel I heat it to orange then shape it with a hammer on the anvil. It usually takes a few heats to get the desired finish I want, and then at that point I quench it in my water bucket.

When the metal gets quenched it will not be red hot but will be hot enough to make the water bubble up, hiss and fizzle.

This allows me to handle the newly forged piece and clean it on the wire wheel.

So my question is

What effect does quenching the, hot piece, at this temperature have on the finished item.

And what would the effect be if it was quenched after being heated to orange.

Cheers Alan

[Greenbeast]

With mild steel it doesn't matter, quench as often as you need from whatever heat it's at.

[La gib]

Hi Greenbeast,

Thanks for the quick reply, that helps me a lot.

I'll carry on practising.

Cheers Alan

[HWooldridge]

Even mild steel can harden in water and although you said it would done at a black heat, habit may dictate that you begin quenching from a higher heat. You will then start noticing pieces that won't bend cold or allow a hole to be drilled. Better to develop the habit of forging and letting it fully air cool.

[Drewed]

It is also easier to brush off the scale before you quench.

[Don A]

If you're using A-36 (hot rolled) from a steel supply or hardware store, I'd be careful about quenching unnecessarily.

The actual steel content is a mixed bag, so sometimes quenching will crack it. especially in thinly worked areas (like fullered necks and split sections).

I use my slack tub on an absolutely as-needed basis. If a couple minutes hanging from the horn or laying on the floor will accomplish the same thing, I stay out of the water.

[Steve Sells]

I only use the quench tub for cooling my tongs, or putting out a grass fire if I am outside doing a demo.

[La gib]

Thanks guys. maybe I'll get in the habit of just laying the work down on the ground out of the way to air cool.

I have just been out dressing the surface of the anvil as it was qwuite badly pittedwith rust when I got it. Got most of it out but some are quite deep. Used an angle grinder grinding disc then going through the grits on the belt sander. Will finnish with the random orbit sander and the angle grinder with the wire cupwheel.

Cheers Alan

[ThomasPowers]

I'm with Steve.

Back in the "Good old Days" when mild steel was 1018 and not A36 (or even very low carbon wrought iron); quenching was the norm having little effect on the metal.

Unfortunately today's A36 is a lot fussier and a floor normalize is a better choice for cooling, (or even hanging on a wire in cold climes)

Arranging your work processes to allow your metal to cool on it's own is not that difficult and the ease of working softer metal can make up the "lost time".

[Dave Huntress]

mild steel still comes in 1018 or 1020 series doesn't it? But thats cold rolled steel or CRS. At least thats what online metals list it as. Hot rolled is softer isn't it? There is such a thing as work hardening as you hammer and stretch sheet metal when working it cold. Probably doesn't happen as much when heating bar stock but my opinion is it does harden the material to some point. As already stated natural cooling is probably best if you have more tasks at hand. If it's a finished piece then why not quench it... just my .02

[Don A]

You can specify cold rolled 1018 and get it from my supplier. It's usually a next day order.

1018 is an actual content designation 10 = simple (no complex alloys) and 18 = .18% carbon (within a certain tolerance)

Hot rolled is A-36. This is a structural designation. It's supposed to be in the "mild steel" range, but the actual content is a gamble.

Think about all of those crushed cars you see being hauled down the interstate. We sell the scrap to China, they melt it and roll it, then sell it back to us as A-36 (perhaps an exagerated analogy, but you get the picture).

Anyhow, I have seen hot rolled that will forge weld, and some that absolutely would not. Some will even harden when you quench it. Some will crack when you forge it, let alone quench it.

A-36 is like a box of chocolates... you never know what you'll get.

[ThomasPowers]

You can get cold rolled and hot rolled in pretty much *any* alloy these days. Do not depend on it being a particular one without a *spec*! (More and more cold rolled A36 is showing up!)

Hammering when hot doesn't affect the hardness at all as it's way above the dislocation climb temperature that "heals" work hardening. (It can affect the grain size in certain situations though).

If it's "finished" why not toss it out into the driveway to cool on it's own?

[pkrankow]

Anyhow, I have seen hot rolled that will forge weld, and some that absolutely would not. Some will even harden when you quench it. Some will crack when you forge it, let alone quench it. A-36 is like a box of chocolates... you never know what you'll get.

It is kinda frustrating when an experienced person cannot even do a simple fagot weld when teaching welding...

If it's "finished" why not toss it out into the driveway to cool on it's own?

My favorite method! Toss it on the gravel under the table.

Phil

[JNewman]

Hot rolled can be 1018 as well. I bought some mild steel round bar recently that the Mill test report listed it as 1018. My understanding of the extra yield strength in cold rolled is due to the work hardening form the cold rolling process. As soon as you heat the bar to forging temperatures that work hardening is gone.

[HWooldridge]

If you want to forge nice soft steel, go find some C1008. It is used for armatures in some electrical applications; hammers like butter and can be drawn into loooong tapers without cracking or breaking. I'd bet you could also quench and drill it with no problems.

[pkrankow]

If you want to forge nice soft steel, go find some C1008. It is used for armatures in some electrical applications; hammers like butter and can be drawn into loooong tapers without cracking or breaking. I'd bet you could also quench and drill it with no problems.

I have a small number of motor guts (3 or 4 pounds) does this stuff forge weld easily too? The individual pieces are pretty thin.

Phil

[ThomasPowers]

The less carbon the higher the welding temp. Of course very low carbon wrought iron forge welds very nicely just at a very high temp!

[Jason @ MacTalis Ironworks]

It is kinda frustrating when an experienced person cannot even do a simple fagot weld when teaching welding... My favorite method! Toss it on the gravel under the table. Phil

We sure saw that didn't we? Like I said, sometimes no matter what you do, you can't get a weld.

[K. Bryan Morgan]

Here's the specs I was able to find. One did say that it could be up to 0.29% carbon however.

Iron (Fe) 99%
Carbon ( C ) 0.26%
Manganese (Mn) 0.75%
Copper (Cu) 0.2%
Phosphorus (P) 0.04% max
Sulfur (S) 0.05% max

[HWooldridge]

I have a small number of motor guts (3 or 4 pounds) does this stuff forge weld easily too? The individual pieces are pretty thin.

Phil

Yes, it forge welds easily. Like Thomas said, slightly higher temps but the seams close up well.

[NeatGuy]

What are transformer laminations made from? They are very soft.

brad

[saintjohnbarleycorn]

since we are talking about this. I have a sand floor, if I throw it on the floor, won't one side transfer heat out fairly well, if the sand is damp? If so should I put it on a piece of steel or something? This is for "don't know what it is mild steel"

[ThomasPowers]

Ahhh steel will suck heat out of it far faster than sand. If you worry put it on top of your vermiculite can.

[Jack Evers]

Since few of us have a way to quantitatively test hardness, let me suggest a simple experiment to show what heat treatment can do to even mild steel. Hardness is linearly related to bending strength. Take a convenient piece of steel, say 1 inch by 1/4 or 3/8. Clamp it in in your vice with a foot or two sticking out, hook a spring scale to the end and note the maximum scale reading as you bend it. Now straighten it out (either hot or cold) heat to an orange and quench. Now repeat the experiment. It will be much harder to bend. Reheat it, cool in ashes or vermiculite and repeat the experiment. It will be even easier than it was in the as received state.

I just did the first two on a piece of 1" by 1/4" cold rolled with the scale hooked 24 inches from the vice. 32 pounds bending strength as received, 52 pounds after heat and quench. A 60 % increase in strength and if I had a way to measure hardness it would have increased about the same. I reheated and allowed the piece to cool slowly in the forge, bending pull was 24 pounds, 75% of as received. I reheated again and allowed it to cool lying on my anvil, bending strength was 30 pounds, about the same as received.

Since the bend will be near the clamped end, It is not necessary to heat treat the entire bar. the first eight or ten inches protruding from the vice is enough. Also note that bending moment is what's important. If I'd have only left a foot sticking out my pulls would have doubled.

[ThomasPowers]

Transformer lams are a clean low carbon steel/silicon mix as I recall as they don't want residual magnetism in them. (and No it is *not* like wrought iron which has a greater silicon percentage and it's totally distributed differently!)