I suppose I could be corrected, but I believe it has been many years since Case put regu0lar carbon steel into their folders.
I started dealing with cutlery in the 1980s, and started forging blades about that same time. During that time, case has been using something called Chrome/Vanadium steel, along with their stainless line.
Chrome vanadium steel is a tool steel that resists rust and corrosion better than regular carbon steel, but to my liking is the same PIA when having to sharpen in a
field situation.
Here's wjhat AI says about Chrome/Vanadium;
AI Summary
To clarify the relationship between chrome vanadium steel and carbon steel, consider the following points:
Chrome vanadium steel is an alloy that includes carbon steel as its base.
It is enhanced with chromium and vanadium for improved strength and durability.
The carbon content in chrome vanadium steel typically ranges from 0.1% to 0.5%.
The addition of chromium increases corrosion resistance and hardness.
Vanadium contributes to better wear resistance and toughness.
This alloy is commonly used in tools and automotive applications due to its properties. Here's a short primer on carbon vs C/V steel...
https://engineerfix.com/chrome-vanadium-vs-carbon-steel-which-is-better/