Stainless steel classification

Alloy of iron and chromium (Cr >12%), nickel is also an important component

Heat-resistant steel

Creep-resistant steel

Corrosion-resistant steel

Austenitic stainless steel

The most widely used stainless steel. The typical content of alloy elements is 18%Cr+8%Ni (18/8), but to increase corrosion resistance, the alloy content can be as high as 26Cr+22Ni. 

Work hardening usually occurs during processing, and the cutting depth should be greater than the surface hardened layer. (Non-magnetic)

Processing is prone to produce:

Chip edge

Work hardening

Poor chip breaking

Ferritic stainless steel

Contains 17%Cr and 0.1-0.25%C, sulfur can be added to improve processability (not hardenable) (magnetic)

Relatively easy to process

Martensitic stainless steel

High carbon content (0.2%-2%), can be hardened. After hardening, it is a martensitic structure. The Cr content is generally 13%-18%. (Magnetic)

Easier to process

Tool application

Try to use small tool tip radius

Sharp cutting edge (reduce chamfering and cutting edge rounding)

Large rake angle

Cutting parameters

Sufficient cooling

Roughing - large cutting depth, large feed rate, low cutting speed

Excessive wear on the back face will make the cutting edge blunt, causing hardening of the machined surface, making finishing more difficult.

Leave enough machining allowance for finishing so that the cutting depth is greater than the depth of the hardened layer.

Reduce cutting speed for high chromium Cr content.