The steel for the plane blades is the D2 tool steel for cold working knifes.
This steel is well responsive to cryogenic treatment. The extreme cold treatment (-320°F) increases the toughness of the steel without any decrease in its hardness. You get increased wear resistance without any increase in brittleness . Thus, a cryogenically treated blade will hold its edge longer and will increase working time without resharpening.
The blades are hardened to 61 HRC
I produce not only blades for my own planes, but I also can offer plane blades based on your own drawings or samples.