“Stainless steel” on a drawing is not enough — the grades differ considerably in corrosion resistance, machinability and price. Here are the grades most often used for turned and milled parts.
The common grades at a glance
| Material | AISI | Strengths | Limits |
|---|---|---|---|
| 1.4301 (X5CrNi18-10) | 304 | the standard, easy to weld, good resistance | not for chloride environments |
| 1.4305 (X8CrNiS18-9) | 303 | much better machinability | less resistant, only partly weldable |
| 1.4404 (X2CrNiMo17-12-2) | 316L | with molybdenum: resistant to chlorides | more expensive, harder to machine than 304 |
| 1.4571 (X6CrNiMoTi17-12-2) | 316Ti | like 316L, titanium-stabilised | harder to machine |
| 1.4462 (X2CrNiMoN22-5-3) | duplex | high strength, very good resistance | tough, demanding to machine |
Which grade for which application?
1.4301 (304) is the right choice for most parts in dry or normal environments, for mechanical engineering and indoor applications.1.4305 (303) pays off for turned parts in larger quantities that are neither welded nor exposed to strong corrosion: it machines much faster, which lowers the unit price.1.4404 (316L) and 1.4571 (316Ti) belong wherever salt, chlorides or cleaning agents are involved: food and pharmaceutical engineering, swimming pools, coastal areas and shipbuilding.Duplex 1.4462 is the choice when high strength is required in addition to corrosion resistance, for example for pump and offshore parts.What this means for machining
Austenitic stainless steels work-harden during machining, are tough and conduct heat poorly. They need sharp tools, a steady cut and adapted cutting data — machining takes longer than with structural steel. In our costing we therefore apply a cycle-time surcharge for stainless steel compared with aluminium.
Our tip: always state the material number and check whether a free-machining grade meets the requirements. More about our stainless steel turned parts.