What NOT to do with 4130

[Mark D. Chapman]

So I had done a weld in some 4130 and I thought I would do a full anneal to make sure any stresses were relieved. I put the 0.050 breastplate in the kiln and followed the process documented in the literature for a full 14 hour anneal cycle.

Result. Heavy scale layers inside and out that flaked away in large pieces. The actual material thickness was reduced to 1/3 of its original thickness as a result of the huge amount of scale formation, ruining the piece.

Nowhere in the literature did it mention that this should only be done in a controlled atmosphere furnace.

Learn from my mistake and avoid this.

Mark
Sadder but Wiser

[Indianer]

Alright... this is bad. It saddens me and I am far away, here across the ocean.

Allow me to make this warning a question: What other typical armouring steels do you guys know that behave like this?

This is valuable. Bad. But valuable.
Indi

[wcallen]

I expect that most normal steels will suffer pretty badly if you let them sit at a glowing temp for much time at all in a normal oxygen rich atmosphere. I know that we certainly got huge scale from just heating/working mild in a huge coke forge.

In armour thicknesses, I expect that "a full cycle" is way over-kill anyway. A lot of this stuff is designed for tool and die where you are dealing with thicknesses that really take a while to even out.

Wade

[Scott Martin]

Shades of Vermilllion's casecarburizing fail!
http://forums.armourarchive.org/phpBB2/ ... 1&t=152996

Or am I the only one who remembers this?

I find that 1050 anneals nicely if you heat to orange and leave it in the forge overnight to cool. The friend who does this for me (and makes knives for a living) suggests just heating to orange and dropping on a kaowool pad, then folding the pad over. This is "good enough" to anneal knives (A2 or 1095) so it should work fine for armour. As Wade has pointed out, the long cycle is intended for large blocks of steel.

Scott

[James Arlen Gillaspie]

We need Craig Nadler in on this discussion. A simple normalizing process won't work on 4130, as it has a tendency to air quench. I do think, however, that it would ameliorate any potential problems with a weld. The reason we like 4130 is that it is very forgiving of sloppy heat treating, bad cross sections, and stress risers in a way that 1050 is not so forgiving, and pretty much alleviates the potential brittleness than car result from a bad heat treat. I might just spend a bit of time holding the weld area at a dull red temperature before allowing it to cool, but that's about it.

[Scott Martin]

Hi James

Unfortunately a lot of the folks who have played with quenching / tempering aren't very active these days. 1050 also air quenches when normalizing - but the normalized material is still much more ductile than if quenched or tempered.

the 10xx series tends to be more susceptible to embrittlement, than 41xx alloys (4130, 4140, 4150 - the latter of which is used in M16' barrels). 10xx alloys will "anneal" (actually normalize by slow quench - most folks working it wouldn't be able to tell the difference) by heating to orange and wrapping in an insulator (whether this is the firebrick of a forge or Kaowool) The "anneal" recommendation is from a knifemaker with >20 years experience (who is teaching me to heat treat, and also anneals my stuff when needed) so I'm happy passing on his recommendations - especially since he gets his info from his boss, who has been making knives professionally for >50 years.

Craig prefers 4130 if he needs to choose between the "simple" steels ecause it has good (minimal) embrittlement characteristics - Dave Wise (Sir Alexis) slack quenches 4130 with no tempering, it's that forgiving. Note that the precipitation hardening alloys behave somewhat differently, but I *think* that they also normalize - they harden using something that looks like a long anneal cycle, and there *is* an annealing protocol, but it is very prescriptive.

When I talked to Wade about heat treating he said that he would just normalize his carbon steel armours, since that was "good enough" to give it the strength needed, and didn't require additional equipment. Alan Williams has pointed out a number of armours that were simply normalized rather than slack quenched or tempered, and this can't be dismissed as accidental.

Back on topic, there are useful instructions to be found for welding materials (such as carbon steels) and the most common carbon steel recommendation is to pre-heat before welding to ameliorate crack formation.

Scott

[Indianer]

1050 also air quenches when normalizing - but the normalized material is still much more ductile than if quenched or tempered.

Scott

We had that before, I know. Just in brief: When you say it air quenches, you mean it technically hardens already. A bit. Thus, the "normalized" yield strength or so I read up in the data sheets is much lower than what I tend to get when I "normalize" in the shop?

When I talked to Wade about heat treating he said that he would just normalize his carbon steel armours, since that was "good enough" to give it the strength needed, and didn't require additional equipment.

Scott

Meaning
1. heat to a uniform orange
2. suspend to let cool in air, not a conducting surface like the anvil
3. that's it. That's a possible way to heat treat.
?

Thanks guys... and yeah, I should have deducted myself that thin sheet flakes away easily regardless of material. I was just so... flustered? by the term "controlled atmosphere furnace".

[James Arlen Gillaspie]

Drat! I forgot completely about antiscaling compounds!
https://www.brownells.com/gunsmith-tool ... 23076.aspx

Most armour ever made of medium carbon steel was air cooled. Then there is a lot of slack quenched stuff during the 15th century. A full martensitic heat treat is a very high end sort of thing, for the most part. Air cooled 4130 is a LOT more resistant to deformation than mild steel.

[wcallen]

Since I am being quoted..

What I have actually done with most of my 1050 armour is to work it hot as needed (for many big pieces, this ends up heating it in various portions of the armour at different times) and letting it cool naturally after the hot work. Then on to the normal plannish and grind and move on from there. I am not doing a full heat/normalize as a separate step. I don't have a kiln.

The material I get is cold rolled annealed from Admiral Steel, so it is pretty soft when it comes to me. The heat/cool that happens from normal hot work does seem to provide a noticeable amount of "hardening" - but not enough that you can't cold work it somewhat significantly afterward without any intentional heat treatment. Just doing significant cold work helps too.

A real heat treat would provide significantly more strength than this. But this is significantly better than mild.

When things open up and I can start abusing John's kiln, I do want to do some real heat treating.

When I have heat treated 1050 semi-intentionally (usually for tools) a quick heat, quench and color run without any soak time definitely works in armour thicknesses. It is easy to test - heat up a piece of 1050, dunk it in a bucket of water, hit it and watch it shatter. No soak required. Definitely don't do that with a piece you care about.

Wade

[Andrew Bodley]

This should be a link to an interesting book on understanding he a treating. It's written with blade makers in mind. But armour uses thin sections of carbon steel. The final requirements for armour are different but understanding how and why is useful.
https://www.google.com/url?sa=t&source= ... iFIj2N11oi
Andrew

[Andrew Bodley]

This should be a link to an interesting book on understanding he a treating. It's written with blade makers in mind. But armour uses thin sections of carbon steel. The final requirements for armour are different but understanding how and why is useful.
https://www.google.com/url?sa=t&source= ... iFIj2N11oi
Andrew

[Mark D. Chapman]

Thanks for the commentary everyone. I lost so much thickness that I am starting over on the breastplate. Practice makes perfect. This time I will not riase so agressively in the armpit area and hopefully eliminate any cracks before they start. I will have to check out that book reference.

Mark