quenching a sword

RAM³ wrote:


Absolutely true, and sword and dagger was well established by then :-) Love the Scot's, the only time it's correct to say blood channel ;-)
Regards Charles
Add pictures here
βœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
If the blade was made out of a leaf spring he should have stress relieved the steel before forging it into a blade i.e. forging the curve in the opposite direction and or normalizing (heating above the critical temp for a long time and cooling slowly) in a heat treat furnace if available Maybe he was just showing off! (what I dont know?) Snewt

Add pictures here
βœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Well there's leaf spring and there's spring steel.
I buy lengths of spring steel and get about 5 standard sword blades and an odd one out of it.
I've never used a leaf springs, as I don't know what it's been through, and there is a lot of bad press about using old leaf springs.
If he was just showing off he deserves a kick in the nut sack >:-(
Regards Charles
snewt wrote:

Add pictures here
βœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Chilla wrote:

re:old leaf springs
Old leaf springs have microfractures in them from all those years of being flexed over billions of potholes, and no amount of heat precesses or forging will remove them. Steel is cheap, why risk a catastrophic failure if you don't have to? OLS is good for machetes, get new stock for blades that matter.
Charly
Add pictures here
βœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Hi snewt. The smith told me that he made it out of a piece of new steel; 1070 as I recall.
Eric

message
Add pictures here
βœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
1070... geez and he's still getting warping, he must be grinding the sh*t out of the blades.
Some stats about this metal:
1070 is a plain carbon (non-alloy) steel
Carbon: 0.65 to 0.75 Manganese: 0.60 to 0.90 Wear resistance: medium Toughness: high to medium, depending upon carbon content Red hardness: very low Distortion in heat treating: very low Forging: Start at 1,750 to 1,850 F Austenite forging: yes Hardening: 1.450 to 1,550 F Quench: Oil Tempering: 300 to 500 F Rc hardness: 62 to 55, depending upon carbon content.
I suspect he's using a higher carbon content steel and he definitely shouldn't be quenching in brine.
snipped-for-privacy@gmail.com wrote:

Add pictures here
βœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If he had quenched in oil and pulled it out as soon as it quit glowing... he could have straightened it out before it "hardened all the way up".
The more Cr and/or Mn in it, the more time you got.
The whole thing doesn't switch to martensite at once, some of the blade is still austenite at some point. Right? ;)
BTDT :) ...with butcher knife blanks and they are tricky as anything to straighten while the sucker is fresh out of the quench tank. :) Using pliers and the oil on it is smoking to beat heck so it's not the easiest thing for me to see either. Especially since I heat treat at night? :)
What's tricky is while you're fiddling with it, the stiffness and elasticity of the blade is changing constantly. The dangged thing is turning into mostly untempered-martensite from all-austenite.
If you got the-warp-out half-way... then about triple that same strain is going to be needed the very next try. It's constantly changing and it's changing fast. :) If you warped it backwards double what it was... ;)
But for a true sword-maker I figure a guy could get good at taking major warps out of the sword fresh from the quench tank and take care of the little warps later after it's tempered? <shrug>
I finish grind my blades extra thin so I have to do the grinding in a two step process, having figured out that a hollow ground blade, the edge needs to be at least 1/32" thick, and I later grind it to half to one third that.
So yeah, a thick-club;) of a knife could be heat treated and polished without later grinding... just not any of my knvies. ;)
I quench in real quenching oil and never use brine but my extra thin 1095, 1.22%C (old files) and 50100-B blades don't need water anyway, let alone the O1 or 8670-M blades.
http://www.panix.com/~alvinj/graphTTT.jpg
See? All you've got to do is get it below about 750F quickly and "you've got it done-quenched ;)" and the time from there, don't really matter if it's cooling in air it'll turn to martensite anyway.
What do you think? :)
Alvin in AZ ps- The swords to beat are Howard Clark's made from L6 (like 4370) bainite using salt tanks. He forges the blades from L6 rounds. pps- don't know why, but swords have never done a thing for me :/
Add pictures here
βœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Jan 27, 8:46 pm, snipped-for-privacy@XX.com wrote:

...
Hi Alvin. Good to hear from you. Thanks for the information. This is useful to remember. So, you use the TTT diagram to tell you when to stop tweaking? The danger zone should be some combination of temperature and fraction martensite. I guess if the blade is balanced (finish ground), there should not be too much tweaking to do. I have never heat treated a knife or sword, but may have to do it one of these days.
Eric
Add pictures here
βœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

http://www.panix.com/~alvinj/graphTTT.jpg (ASMs "Tool Steels")
The line they call the "M point" is usually called the "Ms-line" for "martensite start".
Some older graphs you'll see an "Mf line" for "martensite finish" and those are now considered bogus... there is no "real" Mf-point.
The colder you get it (without letting it stop cooling) the more martensite will be formed from the retained austenite.
That's why I cold treat my knife blades. "higher hardness with no loss of toughness" -Roberts and Cary (ASM)
See the point at 1000F and at 10 seconds? Quench the steel from ~1500F down to and hold it at 1000F for 10s. That's 100% pearlite. Like railroad rail... or the top half of a cold chisel.

Actually that part of it is all in the "feel". :)
The TTT or ITT graph only shows you what's going-on in-theory.
The TTT graph is a road map to show you where you are and what you can get-away-with ...in this case. ;)

Yes, you can see in the graph the temperature constraints you'll need to stay within for certain things to happen... also the time constraints are shown too.
Time Temperature Transformation graph
The graph itself doesn't tell it all... left-out are things like you've got time to plastically deform the part before it gets "too hard" and-so too resistance to plastic deformation etc...
That part's, in the wordy part. ;) Dangged wordy part anyway. ;)
Metallurgy books are my-kinda-books, they are full of graphs and tables and only enough words in between to make sure you "got" everything out of the graphs and tables. Cool huh? :)
I'm not into books without indexes.

Finding-out what you can get away with is in your own hands and tools.
There are a lot of chapters dedicated to warp prevention and suggested steps to take to limit warping. Warp prevention is big business. Take A2 tool steel for an example, tough to find tool steels for sale where A2 isn't listed and it's a "go between" warping vs expense.
"Metallurgy Theory and Practice" by Dell K. Allen ;)
http://www.panix.com/~alvinj/graphFig6-7.jpg
Alvin in AZ
Add pictures here
βœ–
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.