Question about flexible versus rigid steel in fillet knives etc

[Dave Thinkstoomuch]

One knife I really like is Frontier's old fillet knife. Great classic lines:

http://www.collectors-of-schrades-r.us/frontiers/pages/FT-76-6.htm

It came in both flexible (like 167UH and most fillet knives) and rigid blade models. This got me to wondering...

What's the difference steel-wise? Are some types of steel flexible and some not or is it about the way the steel is hardened and tempered?

I have read nothing here to imply that the Steelhead was made with different steel than a Bear Paw so I'm guessing it has to do with how its hardened etc. Any info greatly appreciated.

 

[Codger_64]

In the case of the three Safe-T-Grip fillet knives, the 146OT Minimum Flex (1996-2000) is just a shorter version of the longer 147OT Pro Fisherman (1993-2004) using the same blade stock thickness. To make the 246OT Maximum Flex (1996-2000) version, they used thinner blade stock. I am pretty sure the heat and cryo treat is the same on all three.

 

[Dave Thinkstoomuch]

Thanks Codger. In the case of the Frontier's the two appear to be exactly the same size though which is what made me wonder. Perhaps the flexible one is just thinner but I have had pen-knives with thin rigid blades and thats why I didn't immediately just think thinner stock.