3 of 4 armourers responded with spontaneous laughter...

[Maelgwyn]

3 of 4 armourers responded with spontaneous laughter when they held my old 16g mild steel shield boss in one hand and my new 22g carbon steel boss in the other. The fourth (Krag) also responded with spontaneous laughter, followed rapidly with marking, cutting and hammering out his own boss so that we could heat treat both new bosses in the same batch yesterday evening.

Try the spring steel once and you'll never go back to overweight armour again.

[Robert P. Norwalt]

Sounds cool. Where do you order your 22ga? Are you going to produce them commercially?

[Maelgwyn]

http://www.aedmotorsports.com

and no, but I'm sure others will. I think Krag's was for a commission. His was made of 1050 and shaped for a flat shield. Mine is 4130 and shaped to fit a curved shield, which is a real pain. Max at North Star armoury is also starting to work with 4130 carbon steel and might be willing to fill an order for a boss.

[Robert P. Norwalt]

Thanks

No, I can make my own no prob's, I was curious as to the treatment, and property's. Would have helped if I'd said that, huh? Appreciate the link.

Robert.

[Krag]

Thanks

No, I can make my own no prob's, I was curious as to the treatment, and property's. Would have helped if I'd said that, huh? Appreciate the link.

Robert.

If done right...hard and springy. if done wrong easily bent or easily cracked. We did some test strips using an electric furnace with pyrometer to use as a color/heat reference for when we used the big furnace. We failure tested the pieces. The 4130 seemed to really like 1725*F and quenched into ~140*F oil mix (75/25 veg oil/tranny fluid). The piece was probably closer to 1675 when it actually hits the oil due to moving from furnace to oil in cold Texas air.

When heating, heat up your furnace and turn off the gas. let the piece come to the temp/color you want. Gentle blasts of gas are fine to boost the heat up slightly. You don't want to overheat your piece! If you took it to yellow and scaling bad...time to start over.

Your piece shoul resist deformation, but eventually bend when it fails. if it cracks/breaks when it fails, this could be bad. Splints, lames and such can be a tad harder than things like shild boss, cops and such due to how they absorb a blow...they can bend slightly. Domed items don't give as well. I usually temper at 475 for 30 minutes for both 4130 and 1050. "Roasted to a golden brown with a slight purple tint." Purple-Dark blue is OK also. Light blue and grey is over-tempered and essentially normalized!

That's the extreme short version of heat treating armour. If you start doing it, get some in-depth info and experiment a bit. the above is just a guide and my interpretation of color may not be the same as yours.

I still plan on doing a webpage with several test strips done at various austenizing temps, and quenching temps and quenching mediums. Then, taken to failure.

[Robert P. Norwalt]

Great reply. thanks Krag.

Since the outfit in question is Indy, and I live near there, I'll be able to forgo shipping costs. Sweet.

let you know how it goes.

Oengus.

[Krag]

You might be able to buy drops and such at discounted rates. I've got some good deals in the past on their "leftovers".

[KerryStagmer]

critical temperature for 4130 is listed in Bethlehem steels heattreating book at 1550 with quench to oil. It will need very little tempering say 2 hours at 400 deg in your oven to be 45-48 Rc and it should give no fracturing problems at all.

1050 is tricker as it can see hardness up into the mid to upper 50's where it would be far to hard to use and would break. it is MUCH easier to form not being an alloy, but im much more partial to chromoly (4100 series)

Kaliban would be the right guy to get exact temperatures and tempering times from as he does this all day long at his day job

[mattmaus]

You don't want to overheat your piece! If you took it to yellow and scaling bad...time to start over.

Because I gotta know....

If you do overheat... what then?

I ASSUME. Let it aneal/normalize and then re-heat treat.

[RalphS]

Problem 1: you'll get coarse grain, which means the piece gets fragile, even when tempered properly.
Solution: normalise (preferably a few times), and start over.

Problem 2: you may lose carbon in the surface layers, which means lower hardness.
Solution: recarburise in strongly reducing atmosphere (lots of carbonmonoxide) or with special carburising medium. Generally not recommended for home-use, but not undoable.

One important thing to remember: it's the time at temperature before the quench which is important, not the final temperature just before you hit the quench medium. So the temperature drop between kiln and quench is already part of the quench, not part of the soak.

[Magmaforge]

Try the spring steel once and you'll never go back to overweight armour again.

Vegetius said one should train with triple weight swords and double to triple weight shields, then use the good stuff in war. Maybe grossly overweight armour that creates cumulative joint damage isn't good, but keep the heavy stuff around to practice/train with now and then.
-Mag

[RandallMoffett]

When we talk of grossly overweighted what are we talking about? Historical armour? I am doing some looking right now on this very thing and 22 guage sounds pretty thin to me for most armour historically. Unfortunatly I get weights and not guages from most reading so I cannot say for sure but looking at 18 guage seems to be a nice similar weight between similar pieces. I am currently close to getting a copy of the knight and the blast furnace leant to me so perhaps that will give some more insights on historical armours guages/tempering. As always I have no doubt that tempered steel will hold up if properly done much better than other steels. Just wondering what grossly overweight was relative to.
RPM

[Maelgwyn]

Ok, time for some real measurements. On the postal scale at work the old 16g shield boss weighs 17.5 ounces. The new one weighs 8 ounces.

Anyone have any credible weights for extant shield bosses? It would have to be well-preserved so that corrosion losses are not too significant. Perhaps something from Dura Europos?

[Barnet]

WOW , I could feel they were lighter, but WOW .

[adric]

Ok, time for some real measurements. On the postal scale at work the old 16g shield boss weighs 17.5 ounces. The new one weighs 8 ounces.

Anyone have any credible weights for extant shield bosses? It would have to be well-preserved so that corrosion losses are not too significant. Perhaps something from Dura Europos?

WOW thats inpressive. My kydex ones come in around 5-7 ounces and they are freaking plastic!

[Alcyoneus]

You can buy digital 'radar gun' style pyrometers. Harbor freight had them on sale for $50, but since I didn't have $50, I didn't check on the temperature ranges. I know you can get them in the right range for under $200.

[Krag]

You don't want to overheat your piece! If you took it to yellow and scaling bad...time to start over.

Because I gotta know....

If you do overheat... what then?

I ASSUME. Let it aneal/normalize and then re-heat treat.

IMHO, if you start with 22ga steel and you heat it up to yellow for more than a few seconds, it is now trash. You decarburized all surfaces and probably scaled away one full gauge thickness. Your steel will now be very pitted due to scaling. Cleaning it up will take off close to another gauge thickness, leaving it as is will leave you with a surface so prone to rusting you'll have rusted fingerprints within a minute of touching it...and I can't stand painted armour.

Like someone else said, time above austenization temp is more critical than the max temp reached. I heat my forge up to about 2000*, then cut the gas and place the parts in. They will come to temp, evenly, in about 20-30 seconds. The forge usually cools to around 16-1800* as the parts are coming up to the same temp. If the forge cooled too much, I blast some gas in for a couple seconds at a time to boost the temp slightly (propane will auto-ignite at these temps).


We started at 1600*F but it just wasn't hardening well. Probably because it was about 50* in the shop and it took a second to go from furnace to oil. Thin stuff cools fast! Bumping it up to ~1700 had the best results.

No pyrometers needed.... Know your steel. Do some test pieces and learn the colors of diffferent temps for that steel. Keep your lighting the same. If you're chanigng something up, cut some small test strips and HT them like you plan on doing your piece. When you get the right time/temp, then move on to your piece.

If you have a small volume of quench medium, watch your medium temp. You only need to get down to 4-500* for most quenching, but you can easily get your oil up to 500+*. Sheet metal quenched into 550* oil can do odd things, none of which are desired. If you want a list of what doesn't work...I could provide volumes . Nothing ventured, nothing gained...experiment and have fun!

NOTE: Oh yeah, infrared heat will smoke leather gloves in seconds from a foot away. Reaching into the forge will do it even faster. Hot gloves are hard to get off in a hurry. Never use damp gloves...the moisture will flash to steam and par-boil your fingers!

[RandallMoffett]

Ask and ye shall recieve;

Boss

The iron of the dome was fairly thick (3-5 mm), though the flange was somewhat thinner (Lowe 1990; Manx Museum, Douglas Man: pers. obs. 1994; Musee des Antiquites Nationales, St. Germain-en-Laye France: pers. obs. 1994).

Will keep digging for you though,
RPM

[RandallMoffett]

Maelgwyn,

I was looking for the Dura Europos shield and the sources I found say it was found without boss. It maybe incorrect though. If you have more info let me know,
RPM