Hey guys. I decided to do another test knife since its been a while. I should have taken more pictures of the testing but I didn't, sorry. I am using 1084. First I stuck the tip of the knife in a 2x4 and bent it over several time with no breakage. It pulled up chunks of wood and slightly bent. After probably 10 times, approximately 3/16 of the tip broke off. I was alternating sides, so it was working the tip back and forth. Next I put the blade about 1 1/2 inches in the vice and tried to bend it 90 degrees. As it has done before, the hardened edge broke (deferentially hardened blade). I worked it back and forth 3 times to completely break it to see the grain structure. I dont think the pictures do justice but it is a dull gray, no shimmer. I dont forge cold. I normalize ( over non-magnetic, at non-magnetic and then under non-magnetic followed by cooling down in lime until room temp). I edge quench once in canola oil at 130 degrees and let it cool down with the oil. I temper at 390 twice for 90 min. I dont have any problems with me edge holding ( no chips, no curling). I believe I have good grain structure but I want to bend 90 degrees and not have any breakage. Can I get some help.
Please describe your process for achieving what you call a (deferentially hardened blade). What is your quench process?
Joshua States
www.dosgatosforge.com
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I turn the lights off in the shop, heat the edge with a torch slowly constantly checking with a magnet. When I reach non-magnetic I quench only the edge in the 130 degree canola oil rocking back and forth. for about a min letting the rest of the blade cool off. Then I place the entire blade in the oil and let everything cool to room temp.
If anybody has any ideas on what I could do differently so that my edge won't crack, I would love to hear it.
Chad 1084 is one of the easier steels to heat treat, but it prefers a full quench. I would do a full quench then temper at 400-425. Then I would draw the spine of the blade with a propane torch with the edge in a water bath. Have about one half inch in the water the blue gray color will stop about a 1/4" above the water line. The edge quench will bend very well, but I suspect your temper was too low, and an edge quench is not the best for a knife.
Brion
Brion Tomberlin
Anvil Top Custom Knives
ABS Mastersmith
Thanks Brion. I'll give it a shot. What temp. are you thinking I need to draw the back to? I've never done one like that. I assume not too hot if your suggesting a propane torch?
About the temper: I've never had any chipping when I temper at 390 so I assumed I was hitting the sweet spot. I figured going higher would increase the possibility of have my edge roll when testing. Is the point just to pass the bend test?
So I tried drawing back the spine and tempering at 400 degrees. I still have good grain structure but the blade snapped after about a 30 degree bend. I'll try a higher temp. on the temper and see how it goes.
