Bainitic 1095?

[jdm61]

I ran across a cutlery company whose name that I will not mention at this point that says that their hawks are bainite 1095 at 50-52 Rc and as such, the cat's meow when it comes to toughness. I also read a thread by our own Don Nguyen about his experiences trying to marquench )or is it austemper?) 1095 for a university assignment. His experience and the input he was given on here didn't sound like it was all that successful. Can you make an EFFECTIVE predominantly low bainite structure from a super shallow hardening steel like 1095 or are you going to get some kind of too soft witches brew of bainite (both kinds, country AND western) martensite, RA and pearlite or any combination thereof?

 

[BluntCut MetalWorks]

Maybe great toughness in block/thick form but lousy in edge tools. yep, edge rolls & rolls. Plus it chip big because crack line cascade a long cementite plates. Bainite sheaves use only ~0.4C, leave 0.55%C for cementite precip between these bainite sheaves. If possible, you want to prevent RA to precip as Fe3C but 1095 lacks a couple percent of (each) Si & Co & Mn for such goal. Even so, still not a good fit for edge tools.

Search for prof Bhadeshia's bainitic works. Recently a few threads poped-up in 2 other forums about his super-bainite. LOL - I blah my 2 cents there too.

 

[jdm61]

My understanding has been that 1095 is not a good candidate for marquenching/austempering because you just can't get it past the nose with a higher prettier quench. Are you talking about the "flash bainite? " I Understand that the folks who make armor for vehicles and such are really digging that stuff!!!!

Maybe great toughness in block/thick form but lousy in edge tools. yep, edge rolls & rolls. Plus it chip big because crack line cascade a long cementite plates. Bainite sheaves use only ~0.4C, leave 0.55%C for cementite precip between these bainite sheaves. If possible, you want to prevent RA to precip as Fe3C but 1095 lacks a couple percent of (each) Si & Co & Mn for such goal. Even so, still not a good fit for edge tools.

Search for prof Bhadeshia's bainitic works. Recently a few threads poped-up in 2 other forums about his super-bainite. LOL - I blah my 2 cents there too.

 

[Bo T]

400 F is the cutoff. Fast quench to 400 F, hold for x amount of time. Pull and cool to room temperature. Then treat it as any other 1095 blade. Cold treatment if you want. X will determine the ratio of bainite to martensite. Just info from several papers that I read, and pulling the points from memory. You will need to experiment to get the characteristics that you want.

 

[jdm61]

I know that is the standard recipe, but my question is how do you get 1095 to do that when 400 F quanchant is, by all accounts Much too slow to harden 1095 into a desirable state? Don't you still have to get past the "nose' to form the desirable low bainite?

400 F is the cutoff. Fast quench to 400 F, hold for x amount of time. Pull and cool to room temperature. Then treat it as any other 1095 blade. Cold treatment if you want. X will determine the ratio of bainite to martensite. Just info from several papers that I read, and pulling the points from memory. You will need to experiment to get the characteristics that you want.

 

[mete]

Some years back we had some serious discussion about bainite for knives ,when it was the latest thing !! Maybe you could find some of my posts. There are certainly uses for bainite as the good professor can tell you .He's got a new version of his bainite book which I had downloaded . 400 pages ! But for knives very litle use. The end product , tempered martensite vs bainite doesn't really show any benefit for bainite in blades.Some steels even require very longtimes for proper transformation. No miracle in bainite for blades !

 

[Bo T]

The quench speed from 1500 F to about 800 F is what is really important. In the old days they probably used molten alloy (lead and tin). I'd guess that Richtig may have done this with his knives. Today, I have read that molten salts will work. In either case the heat transfer from the blade to the quenching medium is fast enough to avoid the pearlite nose. In either case there is somewhat more care that needs to be taken then when marquenching into warm oil, water or brine.

 

[jdm61]

I saw a video a year or so ago where one of the old Sheffield firms was still using their old austenizing pots at late as the end of the "last century" The pots used a mixture of lead and mercury!!!!!! Yeah, you can see why there aren't many if any of those systems around anymore!!!

The quench speed from 1500 F to about 800 F is what is really important. In the old days they probably used molten alloy (lead and tin). I'd guess that Richtig may have done this with his knives. Today, I have read that molten salts will work. In either case the heat transfer from the blade to the quenching medium is fast enough to avoid the pearlite nose. In either case there is somewhat more care that needs to be taken then when marquenching into warm oil, water or brine.

 

[Don Nguyen]

I ran across a cutlery company whose name that I will not mention at this point that says that their hawks are bainite 1095 at 50-52 Rc and as such, the cat's meow when it comes to toughness. I also read a thread by our own Don Nguyen about his experiences trying to marquench )or is it austemper?) 1095 for a university assignment. His experience and the input he was given on here didn't sound like it was all that successful. Can you make an EFFECTIVE predominantly low bainite structure from a super shallow hardening steel like 1095 or are you going to get some kind of too soft witches brew of bainite (both kinds, country AND western) martensite, RA and pearlite or any combination thereof?

The biggest problem with the experiment that I did was the hardness tester on campus was calibrated correctly and the samples used for impact toughness weren't suitable to give accurate readings. I wish they had everything set up so that the experiments were worthwhile but it became a game of just numbers and chance, rather than useful data transferable to real applications (ie. there was diminishing return on impact toughness because the samples just bent and flew out).

With a shallow hardening steel I think it's more difficult to get bainite. Even with the theoretical quench speeds of salts I remember a few people having trouble getting the desired hardnesses for martempering and austempering.

I'll be playing a bit with bainite in 2015 again, just for the heck of it.

 

[jdm61]

Don, I would think that for the kind of blades you make, hard as woodpecker lips martensitic steel would be the preferred material.

The biggest problem with the experiment that I did was the hardness tester on campus was calibrated correctly and the samples used for impact toughness weren't suitable to give accurate readings. I wish they had everything set up so that the experiments were worthwhile but it became a game of just numbers and chance, rather than useful data transferable to real applications (ie. there was diminishing return on impact toughness because the samples just bent and flew out).

With a shallow hardening steel I think it's more difficult to get bainite. Even with the theoretical quench speeds of salts I remember a few people having trouble getting the desired hardnesses for martempering and austempering.

I'll be playing a bit with bainite in 2015 again, just for the heck of it.