A little experiment

[Doug Lester]

One of the steels that I work with is 9260 and not too long ago it was pointed out to me that it was a steel that would display a quench line or hamon with clay quenching. So I decided to make a test blade with it and give the technique a try. The blade below was forged, given a rough grind and coated with furnice patch that I had thinned out just slightly with water before applying maybe 3/16" thick. It was austinized to a little above non-magnetic and quenched in peanut oil heated to about 130 degrees and tempered at 400 degrees. I actually had to harden twice because I didn't achieve good hardness the first time around. I figured that I didn't quite achieve austinization the first time around so I repeated the process getting the steel just a little hotter. No soak other than to make sure the steel was heated through.

I ground it out to 600 grit on the grinder then switched to hand sanding with WD-40 as a lubricant. I took it all the way out to 1500 grit, hoping that I might see something with just polishing. Nothing showed with polishing but it popped right up with ferric chloride mixed 1:4 parts in distilled water.

Below is the knife which will be given a simple handle and tested with chopping and slicing before I break the blade to check toughness and grain size. I did experiment with a hollow grind on the clip, but that didn't turn out well.


Doug

 

[franklin]

Doug never worked with 9260,what does it resemble? and were would you get it?
Never heard of it.

 

[Doug Lester]

I get my 9260 from Admiral Steel. They only have it in two sizes and they list it in with the 5160 for some reason which is close to it in heat treating and use. It is a high silicon alloy, about 2%, with a little chromium. The silicon makes it want to retain austinite on quenching you I would deffinantly be sure to temper three times to get as much to convert as possible. In depth or harding it would be between 1060 and 5160. From the IT diagrams that I have it will start forming "free" ferrite, ferrite not associated with pearlite, on slow cooling in less than 1 second, a lot sooner than 5160, but won't start forming pearlite for at least 2 seconds. I'm assuming that this rapid formation of the "free" ferrite is what gives the differential hardening as represented by the difference in the etched areas. I don't have the money to send a blade off to a lab for microscopic analysis of crystaline structure so I don't know if the spine is free of all martensite or not.

Doug

 

[kevin - the professor]

Well, I will be darned. I had no idea that could work. How did you lay the clay out? was it a straight line like the hamon, or did you put curves and ashi and just get a straight line anyway? I now want to know if it responds to ashi and such. If you could coax some activity out of it, then that would be a good alternative for a sword blade, for sure.
kc

 

[bubba-san]

I like 9260 . Made a few swords and blades from it . Takes a pretty fair hamon . The metal seems to have better lateral strength than 5160 .
pic of 12 " tanto .

 

[Doug Lester]

I wasn't wanting to get too fancy with this so I layed the clay out with a flat edge. I was looking more for evidence that the blade could be differentially hardened by clay coating. I too assumed that 9260 was a more deep hardening steel until someone else posted picture of with a blade quench line. As I said, it starts to form proeutictic ferrite (I guess that's the correct term) rather quickly, though it takes about another second to start forming pearlite. I may just have to look up a lab to get a price on microscopic testing to see what the mixture of crystals in the spine is.

Doug