Which stainless steel type is known for its high strength and toughness?

The type of stainless steel known for its high strength and toughness is often 420 stainless steel. This is a martensitic stainless steel, which is characterized by its ability to attain high hardness and strength through heat treatment. The structure of 420 stainless steel allows it to be hardened effectively, making it suitable for applications that require both strength and resistance to wear.

Additionally, it offers good toughness, which is critical in resisting fracture and deformation under stress. This combination of properties makes 420 stainless steel suitable for blades, surgical instruments, and other critical applications where durability and performance are vital.

By contrast, while the other stainless steel types listed do have distinct properties, they do not match the specific combination of high strength and toughness found in 420. For instance, 316 is known for its corrosion resistance, 304 is recognized for its general good performance in various environments but does not have the same strength characteristics as 420, and 202 is considered an alternate material with lower corrosion resistance and strength than the martensitic grades. Thus, 420 is the most advantageous choice when high strength and toughness are the primary requirements.