welding 01

[dbalfa]

I built a through tang knife out of 01 and where I oxy/acet welded the tang bolt onto the tang broke just behind the weld - the 01 tang broke that is. So I ground it down, re-fit it and tried again, this time with a mig welder, which was my first choice but was out of gas. I heat-sinked the blade and got what I thought was a good weld, ground it smooth and tested it on the anvil and, as you probably have guessed, it broke again, much the same way. So now I am running out of tang in a hurry and figured I better raise the white flag for help- What am I doing wrong? I'm letting the weld cool to black before I quench, should I let it air cool?

Thanks

[Doug Lester]

I think that Wayne Goddard favors brazing the tang bolt onto the tang stub rather than welding it. You may well have a problem with the tang stub austinizing when you weld the bolt on and then it air quenches and forms untempered martensite in the O-1 when it cools.

Doug Lester

[brucegodlesky]

preheat and postheat should solve yer problem. I migweld stubs and take it to a blue color and inch or so either sid eof the weld.

[dbalfa]

Thank you gentlemen!
It is becomeing obvious what caused this failure.....PPM! That I can address-

[pipecrafter]

Dennis,

I've mig welded a stick tang (not a bolt tang) tang onto O1 before with no ill effects - but I weld it on prior to heat treat, and even prior to grinding in some cases. I have no idea if this is "proper" or what, but I've never experienced any failures this way.

[mete]

If you weld high carbon steels like O-1 you will form martensite . That must be tempered right away by postheat..It's a good idea to preheat also.

[pipecrafter]

Thanks Mete, I'll definitely be doing pre and post heat in the future.

[dbalfa]

I did as was suggested by Mete and others - pre-heat, weld, post-heat, and it worked well. I did first do a test piece and I could bend the 01 or all-thread without damage to the weld or metal. Welded the blade and it passe the test as well.

THANK YOU Gentlemen !