The Armour Archive

I bought some 1050 and I want to try a basic heat treating. I under stand that you bring the steel to temperature then quench. What I don't understand is if you quench it or not when you heat it up for the temper.

You do not typically quench a 2nd time. Heating an oven is expensive in an industrial application. If you were thinking of going 6 hours then quenching you could go 5:45 and then turn the oven off to slow cool for the same effect but 4% less fuel cost. The quench wouldn't get you anything structurally or chemically anyway.

Sean

The temper is a prolonged soak at a given temperature for a given time. When I am tempering knives I do not quench after the heat cycle, I let the blade cool slowly to ambient/room temperature before putting it back in the oven for the next cycle. Occasionally if I am in a hurry to move on to the next step of polishing I will dunk the blade so I can handle it.
Most manufacturers will publish a heat treat guide for their particular recipe of a steel, and then there is the Bible http://books.google.com/books?id=boKzK- ... de&f=false Which is now handily available from Google books.

Thanks that answers my question. Let me explain a bit better what i mean when I say basic treatment .I am treating a plate basket hilt. I am heating the piece in my wood burning furnace. I can get the steel to a bright orange. I plan on doing the tempering in my gas oven.

Seems like a reasonable plan. Bright orange is 2000F so you can loose a few degrees before you hit the quench tank. An oven will get you into the low range that the book recomends tempering at (600F) although other armorers report getting good results as low as 450F.

http://forums.pelicanparts.com/uploads1 ... 810183.jpg

Thank you Sean for your quick reply. Now to try it out!

Yup. Bring it up to bright orange (I would check for non magnetic with a handily placed welding magnet or something similar) and quench.
Polish off any fire scale so you can see your tempering colors and toss (place) it in the oven at something over 400 degrees.
Farther on in the book I linked is the tempering curve for 1050. http://books.google.com/books?id=boKzK- ... to&f=false
(upper right hand graph) It shows that at 400 degrees you will get about RC 55 and at 600 you will get about RC 50 with 0.125 soaked for an hour.
That will be a bit harder than spring but still pretty resilient.

I'd try it out and see how it goes.
Make one and toss it out there, bet the guys they cant break it.
Keep tuning your process until you have an indestructible piece.

Looking forward to seeing the results!

Oooh! I'm saving that page to link to when others ask questions about heat treating. Very useful.

The 55->50 Hrc difference is notable but mostly from a scratch resistance standpoint. It's not a linear progression with strength. If you look at yield and tensile (ultimate) strength on the next page which only goes as low as 600F you see that tensile (ultimate) strength regresses upward but that yield strength is pretty horizontal. That's not uncommon in steels tempered in these ranges. If you look at % elongation and % reduction in area they also regress in the downward direction indicating that the material is more brittle. In general if I can get similar yield strength (which is dent resistance) at 600F as 400F but make it less brittle (cracking) I'll take it. I can hammer out a dent but I have to outsource welding a repair and a weld repair messes up the heat-treat.

The key is "State your assumptions". The table stipulates a 38mm (1.5") round bar. That's pretty different then .040" steel sheet. It's possible to see a shift in the table based on geometry. That's where practical experience and testing take over. It's quite possible that 400F IS better then 600F as a combination of HRC, Yield, Ultimate and %elongation but it would take a lot of testing to prove or disprove it. Right now personal experience might be the best rule.

Ultimately I doubt our medieval forefathers had IR temperature guns, convection ovens with digital thermometers and factory precision steel. They worked by eye and by feel. Heat to the color of a oak-leaf in fall, quench in water and urine as cold as a deep well and re-heat until the olive-oil ignites on contact is probably as scientific as it gets and it still worked for them.

Sean Powell

My recipe for 1050 is hear to 1650 f then quench in hot water (from the hot water tap) then temper at 675 f for an hour. Having accurate temperatures is pretty important I suggest investing in a pyrometer

I would love to know how ticklish this stuff really is and what ranges really work. From his mid-14th c. BOTN thread, Craig says:

I'm starting this thread for the parts of a mid 14th century ACL/BotN kit that I'm building as an example beginners kit. The suit is all 0.040"/19ga/1.0mm 1050 spring steel except for the helmet that will be 0.090"/13ga/2.3mm 1050 spring steel. The all armour plates will be heated to 1500F/816C and quenched, then tempered for 30 minutes at 650F/343C, and blackened with linseed oil at 570F/299C. The buckler is tempered for 30 minutes at 600F/316C.

He doesn't appear to say what his hardening quench is.

I expect that if we ask really nicely we would find slight differences in every armourer's hardening and tempering methods.

If anyone else who actually does this wants to chime in, it would be fun to hear differences. I would think that a reasonably complete description would be:

I heat the armour to xxxxx temperature and hold it there for tttt time using yyyyyyy (what yyyy is will give us some idea of how precise this is) and quench it in zzzzzz at ppp temp making sure it doesn't drop below ttt temp. I then temper it to qqqqq for rrrrrr using sssss (which will again show precision) within ttt time of the hardening process.

I threw some of these variables in because I have instructions for tempering 4130 that say "don't let it get below 100 degrees between hardening and tempering"... which appears to an unnecessary step with my 4145 since I waited a day to temper it and it (so far) seems fine in my power hammer heads. I haven't tested an additional anvil I just made yet, but it will have gone below 100 as well.

I expect that some of these people are using electric kilns with digital systems that will hold a temperature. It appears that others are being much more freewheeling.

Anyone care to fill out the survey? I expect many of us would like to know.

Wade

I really only temper tools, so I checked with a buddy who does harden and temper 1050 and got:
Well, it varies based on several things, but mainly thickness of the material.
After that:

I heat the armour to 1425F temperature and hold it there for 5-10 minutes time using a digitally controlled electric kiln and quench it in transmission fluid (or water, but trans. at the moment) at <no particular temp>. I then temper it to 500F for somewhat longer than the soak time for hardening using the same electric kiln used for hardening (mainly because the pieces are now coated in transmission fluid and it makes a mess of the house if you use the normal oven). The soak times are short because the metal is way, way thinner than anything the charts use as a basis for calculation.

I heat the armour to "1600F" temperature and hold it there for "1 minute" time using "the timer on the kiln" (what yyyy is will give us some idea of how precise this is) and quench it in "water" at "room temperature". I then temper it to "650F" for "30 minutes" using "the timner on the kiln or a clock" (which will again show precision) within "1 or 2 hours" time of the hardening process.

Best Regards,

Craig Nadler