Gonna order some steel, can you help me make up my mind?

jonathan creason

Well-Known Member
Since it's pretty much universally agreed that beginners should stick to known steels I'm looking to place an order with Aldo. I'm considering something in the 1075-1084 range, but I can't make up my mind as to which one. According to Aldo's site 1075 is a water quench steel, which makes me a little leary (mostly because I've never tried it). Anybody have any strong opinions as far as a preference goes?
 
Simple steels such as the 10XX and W series are very easy to heat treat. Just because a steel is water quenching doesn't necessarily mean that it needs to be water quenched. Most can be oil quenched but I have used some 1095 that the oil that I was using wouldn't put a hard enough edge on, I think that I was edge quenching in my version of Goddard's Goop, and had to result to a brine quench. That batch of steel might have done well with one of the commercially available super fast oils designed for agressive cooling of shallow harding steel.

The 1075 is pretty much a eutectic steel. That means that in the austinitic state the crystals will be saturated with carbon without any undisolved carbon left over to form cementite. It will also be harder that lets say 1060 due to the higher carbon content in any of the conversion products of austinite. It will also produce little, if any, free ferrite when cooled in air as opposed to the 1060. This will produce harder, more wear resistant but less tough and ductile pearletic steel. Also the plates of ferrite in the pearlite will be thinner and the plates of cementite in it will be thicker with the same result. The nose of the ITT curve will also be a little further to the right than the 1060 and easier to miss during quenching.

The 1084 is supersaturated with carbon when austinized. There will be carbon left over in the austinite to form cementite that will remain when the steel is quenched contributing to increased hardness and wear resistance. All ferrite that is formed will be in the pearlite formed during slow cooling. The martensite formed on quenching will have have more carbon trapped in it and will be harder as quenched and may require a slightly higher tempering temperature that the 1075.

All that said, there is probably not all that much difference between the two steels based on carbon content; not nearly as much as between 1060 and 1095. You will probably have more of a difference between the manganese contents of the steel. The higher the manganese content the higher the hardenability of the steel. You will have to ask Aldo which one has the higher level but I think that the 1084 has the greater manganese content. Basically the 1075 will be slightly tougher than the 1084 and the 1084 will be slightly more hard and wear resistant than the 1075 with the nose of the ITT cooling curve slightly more to the right based on the carbon content. Both are shallow hardening steels.

Doug
 
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Thanks for the response, Doug, that's a lot of good information. I don't have any plans to make any big blades that would be subjected to anything needing toughness with this steel, mostly EDC's and skinning knives, so I think I'll opt for the 1084.
 
Glad to be of help, Jonathan. Actually that was sort of an overview hitting the high points. There are a few other things that go on with heat treating, phase changes, and composition. Studying steel metallurgy has taught me that it's not all that straight forward, that more than one thing could be going on, and a lot of statements depend on a specific set of conditions. I worry a bit when I take off on a disertation like that that I'll either make a mistake or loose everyone with the details. To quote another person who posts on these boards: in theory, theory and practice are the same thing, in pratice they're not.

Doug
 
I had trouble ordering online, so I gave Aldo a call to discuss it with him. He also highly recommended the 1084 too (and was a pleasure to chat with to boot). It's a lot of new info, Doug, and keeping up is tough at times but it's info I need to learn. Thanks again for your help.
 
I'd stick with the 1084 for now. I think that 1075 he has has a very low manganese and thus needs a very fast quench, but perfect for hamons...
 
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