hunterNDN

mixed results heat treating 1045

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Hello everyone!

So I've been blacksmithing for several years and have been following this and other forums equaly long but have never posted anything yet.

But now I have a question. I've been heat treating several hammers and axes lately and have not gotten the hardnes I wanted. The hammers are axeptable I think mid 40's HRC (still a bit on the soft side compared to my reference pieces of 1045 but doable) The axe (mordaxe with blade and poll) just realy does'nt want to the blade didn't harden after 2 attempts and the poll only slightly I think low 40's Its about as hard as an old normalised leaf spring I have lying around here. 


So some parameters. hammers and axe are made from ,the same stock of c45. I'm hardening in brine 4pounds of salt in 4gallons of watter and added some dishwasher. Heated to 1500-1550f° (I'm gaging temperature by collor so maybe the pieces where a bit hotter but not hugely so). Did not let it soak for 10-15minutes per inch of thickness though but never had any problems with that before.Quench by Plunging and agitating until it stops screming  then let the residual heat temper the piece to about straw and  try to keep it at that temp for a couple of minutes. Normalised the pieces before hardening (only do 1 normalising sycle for thicker stuff). Heated to 1500-1550f° (I'm gaging temperature by collor so maybe the pieces where a bit hotter but not hugely so). 

I was wondering If anyone had an explanation for this? note the axe took a lot of heats to finish could it be decarb? checked hardnes before and after removing some of the top material.

 

PS.

Sorry if I didn't pose the answer in the right topic and excuse me for any spelling mistakes English isn't my first language :p

 Thanks in advance!  Nick

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Sounds like a good sequence to me.  Surprised you are only getting mid 40's Rc, how are you testing that?  I have been successful with simple water quenches for hammers made from 1045.  Not sure if c45 is the same though.  Are you completely certain of your alloy?

As far as axes, I've only either made them from higher alloy steel (at least 60 points carbon), or forge welded in bits of up to 1095 steel.  You can certainly get decarb on many successive heatings to forging temperatures, but I don't know how far that will penetrate the thickness.  Did you experience a lot of scaling?  Gas forge or solid fuel?

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Hello, thank you for the fast reply!

I'm working in a side blast forge with cokes.

c45 is very similar to 1045 , should at least heat treat similar to 1045 as far as I know but maybe someone with more knoweledge about alloys will chime in.

for the rc, I tested it (read bang together and look at the dents xp) against a piece of c45 that I heat treated sucsesfully.  should be about 50rc I recon  (some testing it against files , testing it for rebound banging it againsdt other pieces of steel :p) i don't have a RC measuring device nor some of those testing files so the only thing i can do at the moment is  look at what the steel does compared to other pieces with a known or at least better known rc. If you know a good way to accurately test the rc (without having to dish out large amounts of money) please do tell. bottom line is,the hardness i'm getting is softer than what I'm used to which would be spearheads and hammers, all be it smaller ones about 30mm square and poleaxes also about 30mm square)

As far as the thickness of the axe goes. The beard is only about 1/5 of an inch in thicknes and the edge  itself is 2,5mm  (blunt axe head for reenactment) and there was enough scaling indeed, don't have a power hammer and have to do everything by hand without a stricker. relatively heavy stoch 40mm square and upset  it for more material at the blade end.

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Thank you!

I have updated my account and added my location. As for the rest of the information I knew most of it but thank you for the reminder!

 

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Hello Thomas,

already ground into it to rule that out :/  But I'll grind off some more tomorrow. I'm going to try a third hardening anyways after some testing with the parent bar. but thank you for the heads up.

is it possible that the blade is not very thick and it didn't have that much carbon to start with, even the core is decarburized to much to realy do anything? I don't know to much about decarb so I don't know how deep the layer of decarb can penetrate especialy in medium carbon steels.

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A lot of that depends on your work methods.  If this is for re-enactment fighting they probably have requirements on what alloys can be used; so going for a higher C might not be allowed. If it's for re-enactment display or non-fighting use I'd try something like 1084 and temper the poll/eye/body back while leaving the edge purple to blue.

I have seen a number of cases where students leave their knife blade in a gas forge and go off to get a snack and later wonder why it won't harden...They also do not remember that blades should be done in as few heats as possible. Or the reason why a large forge is often worse for doing long blades than a small forge.

 

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I've been making re enactement  weapons for about 6 years now and Have made them out of 5160 (or something similar they were old leaf springs) or c45 which is easy to get I normaly keep 1084 for my knives. as far as alloying is concerned never heard any rules about it. it's generaly the shape of the "point" and the state of the edge that is important (although that has a relation to the hardness of the material). 

 i've had a bottom blast with coal, a atmosferic gas forge on propane and my current one side blast  mostly fired with cokes (and sometimes soft wood coal which I make here from time to time) and scale and decarb can be a problem with al of these options but mostly with smaller items the number of heats doesn't get out of hand but this particulat piece has a lot going on if you are doing it by hand and it might be that the blade just doesn't have the juice left for any substantial hardening :p then again a soft blade is better than a brittle one  in mock fighting  and at least it's still harder than mild steel :p but it's still a shame if it doesn't come out like you intend it to. 

on the other hand this is try 2 the first try was made from a piece of railroad track but something similar happened, to much heats ,to much working time, (there's quite a difference in material needed  to make a pollhammer head as oposed to a mordaxe, about twice the material in the blade area) and cracks appeared in the blade and poll (or it is not the composition of steel i believed it to be  althpough I did an oil quench)

It might simply be better to make these "bigger " items when I finally start and finnish my forging press, but funds won't allow it at the moment.

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As to your problem.

I'm old fashioned. I always anneal as part of my heat treat procedure. I also use the mark one eyeball to judge colors.

Make sure you have a constant light source. 

Forge

Normalize

Anneal

Cold work

Harden

Temper.

 

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First let me say that you have much more experience than I do so this may sound silly since it's pretty basic but  ,Is your fire  too shallow? That will cause excessive scaling. Did you test with a magnet?  Depending on the light I have a hard time judging colors sometimes and without a magnet I've been pretty far off the mark before. As I said though you have much more experience than me and I'm sure you've taken the things I mentioned in to account but there's a slim chance it may be of some help.

Pnut

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On 11/11/2019 at 6:17 AM, pnut said:

Depending on the light I have a hard time judging colors

If you are forging outside or don't have a constant light in your forge, consider a "dark box". This is a wooden box, 5 gal bucket, or the like. Put your hot iron in this to be able to read your colors more accurately.

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Teaching bladesmithing, especially when using alloys with very limited forging ranges, I keep having to point out to students that as the ambient gets darker the steel looks brighter and so what looks barely warm enough to forge at noon may look at the upper forging range in the evening.  The dark box can help that out too!

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Interesting.  That got me to look up the diagrams in the heat treater's guide just to see if I could spot something going on.  With 1045, the final hardness is severely affected by the part size. A 2" dia bar will never get above about 40HRC at the surface and more like 30 at the core when quenched in water..and way worse with oil.  This stuff hates larger profiles in it's hardenability.   A 4" dia bar will never get above 30 HRC no matter how hard you try.

FYI, the book wants a water or brine quench for anything above 1/4" thick or you'll get nearly nothing for hardness.  Oil only for thin sections.

Oh...and one more weirdness.  The book has a chart of hardness variation based on pull-tests at a commercial operation.  Doing everything perfect and consistent, they still got 20-25% variation in hardness over a 2 month run period--and it was a pretty flat bell curve so those outliers were not just the random oddball but fairly common to see.  Coming out low was more common than coming out high.

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Thank you all for answering and sharing your ideas and oppinions! Much appreciated!

Also ,sorry for the late reply. Kinda lost track because i was working it out on my own and the notifications landed in the spam :/

But what I found out may interest anyone who ever has the same problem. It is quite in line with what Kozzy has shared.

So i took different stock of what i baught for c45, hardened different pieces with different methods and did several pieces in different temper collor of each stock. (everything was forged down to similar size in a couple of heats first) and the stock i used for the hammers was noticably softer than  my ussual stock but still useable, so if they bothe were c45  then indeed the results can noticably deviate from stock to stock.

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Most professional blade makers I know have had at least one incident of being sent the wrong steel from the Manufacturer/Dealer. That might be a possibility in your case too.

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One thing that can be used in sun light or a way to see when transformation temperature (hardening temp)  is starting to take place is a magnet.   I have not met a steel or alloy of steel that remains magnetic when in transformation temperature.  

As the steel goes thru this range it will be nearly the same time an time again temperature wise..  So, even in direct day light the magnet can help with seeing (the magnet will not stick vs stick) the temperature. 

Once the steel becomes non magnetic try to keep that temperature for a little longer before hardening to get a heat soak.   don't go any higher in temperature and don't go to long in the soak as both will increase grain growth/size. 

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The problem with a magnet is that simple carbon steels become nonmagnetic at about 1420F/770C, but the critical temperature for hardening is actually between 1450F/788C and 1500F/815C depending on your alloy. A magnet will show you that you're getting close, but it won't show that you're actually there.

However, Latticino showed me another trick that works even better than the magnet: SALT. Plain table salt (sodium chloride or NaCl) melts at 1474F/801C, so if you sprinkle some salt on your workpiece and it melts, you're at or above that temperature. I've had very good results with sprinkling some salt on my workpiece and putting it in the gas forge; when the salt melts, the surface is at 1474F.

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Ah, Good point on the salt..  i don't carry salt when I'm on the road but have a bunch of magnets I have pulled and stacked on the side of the forge.  LOL..  Salt would end up a huge chunk in a short order in the trailer. 

I  find the magnet it's usually close enough..  the basic concept is what was being shared..  The variance in just how archaic forging and heat treatment really are is such a wide spread or wide temperature spread to still arrive at good results.     People often get hung up on technical spec's yet for some reason things still work when not at the technical specs.   Working with metals is probably one of the most widely spread variations type thing that can be worked with..  It's crazy how things can work out. 1350 to 1800F are the overall transformation temperatures.. So there is a lot of wiggle room depending. 
 

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One nice thing about the salt is that you can use it on the entire piece all at once. I remember working on one blade (the longest I've attempted to date) and realizing that while the salt had melted along most of the length, there were two significant spots where it hadn't. I could easily have gotten no magnetism for most of the length, but if I missed those areas, I would have had two major soft spots in the blade.

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So, was it simply an uneven heat that created the colder spots (gas forge)?  If that works for you. That is the only important part..  It's another tool in the belt. 

I feel there is more there than just salt or tempil markers or which have you.. even Magnets.. It's all starting point.. Not an end..  

Technique, technique, technique.    (You could switch these with knowledge, knowledge, knowledge or skill set, skill set, skill set).. 

Having the tools in the belt that allow for further development if desired is the important aspect.  

And now you have a great tool in your belt of tools.. Nice.. 

 

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Another trick is to have a magnet hanging below the forge on a length of cord. If a piece is still magnetic, the magnet will pull towards it; if it’s not, it won’t.  

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Decalescence is the BEST way to judge critical temperature

 "De"as a prefix means "to be away from", or "without" and "calescence" means "to warm up" in Latin. So, "decalescence" means (roughly) "to be without warming up".

Since energy is matter, and matter is energy; the steel will release light and heat energy When heated. When you heat the steel to a certain point, the steel begins to change its atomic arrangement. Such a change requires energy to accomplish, so the steel cannot emit its light energy, and heating may slow down. This creates a visible "shadow" in the steel that can be used as a waypoint in the normalization and hardening processes. 

 

What your looking for is when the steel darkens or forms a "shadow" at the temperature right before you would be ready to quench. You continue to heat the steel until the shadow brightens until it becomes the same color as the area just outside of the shadow. You want to heat as evenly as possible until the shadow is gone. Heat thicker areas first, and then move to thinner areas. I pull my blade in and out of my forge's hot spot to achieve even heat. Some use a pipe capped on one end inside of the forge to create an even heat.

This phenomenon is best seen in low light conditions and is used for both normalization and hardening

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I too learned to heat treat with a magnet. Lol, like has been said, the loss of magnetism happens just below critical temp. So I always bring it to that point, then just heat it a little more.

How much more? Like a good cook,,, just a "pinch" more. I once asked a cook "whats a pinch", and his answer was "about 10 years worth of experience!"  Works for me.  ;)

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