Stainless Steel Type 316
The finger planes are made of stainless steel does not readily corrode and it's much more harder than brass. 316 grade is one of the most common stainless steel used primarily for its increased resistance to corrosion. It’s, both strength and beauty, and that's also the reason why it has long been used to make fine watches.
Blades made of hight-speed Steel(HSS), approx. HRC 60-62
It's superior to the older high-carbon steel tools that it can withstand higher temperatures without losing its temper (hardness). This property allows HSS to cut faster than high carbon steel, hence the name high-speed steel. It is often used in power-saw blades and drill bits sed but we also use it in fine hand tools where their relatively good toughness at high hardness, coupled with high abrasion resistance, made them suitable for low speed applications requiring a sharp edge.