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I'm having trouble coaxing hardness from a sword-length 1050 blade I'm working on. File still half-bites and doesnt full-skate after a water quench. (I made sure I verified my eye-balled temp estimate with a magnet to check that it was at non-mag before quenching.) Am I asking for too much hardness from a simple 1050?

 

Forged out a cut-off into a blade-shaped section and quenched...same results with the file test though I can get it to snap in the vice. I'm suspecting the "1050" I was sold is lower carbon stuff. Does the fact that I can snap it in a vice but not get it to pass the file test mean anything in terms of guestimating C content?

 

...Man, I wish I could get some half-decent steel out here. :angry:

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Unfortunately I do think that the quality of the steel that we get varies greatly from batch to batch and that the specs from the factory don't necessary apply to your particular iece of steel.

I've never had problems getting my batch of 1050 to harden correctly.

I am about to run out of this batch and I am dreading getting a new order.

I think is best to get a larger order so that you have enough material of hopefully the same quality and then figure out your heat treating for that batch and stay consistent. But if you get a "bad" batch then you are stuck. Well you can always use it for pattern welding.

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I've made some chisels out of 1040, water hardened at bright red, and they easily reached full hardness.

If your 1050 doesn't harden well probably it is around 0,30%C. Maybe spark test could help you to find out if the carbon content is so low.

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The fact that is snapped in a vise indicates that you got a predominately martensitic structure. However, the ultimate hardness is governered by the carbon content. The range of carbon in a 1050 steel is approximately 0.48-0.55 - so can vary. Aslo, you may have some decarb.

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Sounds like the mower blade I made. It'd harden but not extremely hard. Other high carbon would shatter when struck, the mower blade wouldn't, but it'd snap with some force while in the vise. So it did get hard but I'm thinking due to the carbon content, it didn't get extremely hard. And like Scott said, I might have had some Decarb as well.

 

I saw a new blade packaged up at a hardware store and it said "high carbon" but if the one I used was the same steel, there's still no telling what they are calling "high carbon" =P

 

Could be a same sort of thing.

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In case it helps anyone else with a similar problem...

 

I had another go at some tests with this batch of material and found what it wanted was a looong soak ('bout a minute or two even!) at slightly higher temp than I would normaly austenize at. Test piece seems to have no appreciable grain growth and now passes the file test.

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'High carbon' could mean anything over 1040 for consumer stuff. Where do you get steel in the Phillipines? I don't get a lot of scrap around here that isn't 1008-1010, which I might use in place of iron for fittings and stuff. I order bar stock from Admiral here in the US.

Is there much decarb happening in a salt bath at all? I didnt think that would be a problem with molten salt.

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Decarburization can be a problem in molten salt at elevated temperatures of austenitizing. It could from a salt bath that needs neutralization. One easy way to check is called the razor blade test. Take a steel razor blade - not a stainless one, and immerse it in the salt for an appropriate mount of time for your blade or part. Remove the razor blade, and quench it in cold water. Wearing gloves and safety glasses, put the razor blade in a vise, and use a pair of pliers to bend it. If the blade snaps, decarburization is not a problem. If it bends and deforms, then the bath needs rectification.

 

Scott

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The non-magnetic temperature is about 1430F and only .80C steel will be fully austenitic at this temperature. Lower carbon steel needs about 75-100F more heat to become fully austenitic. If you quench without getting fully austenitic, you will not form as much martensite as is possible and hardness will be lower than expected. Also, try normalizing first, this will help break down carbides and distribute the carbon for more uniform hardness.

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