MS vs SS316: choosing the right steel for your turned part

One of the first questions we ask on any new part is simple: what does it need to survive? The answer usually points straight to the material. Here is how we think about the two families we machine most.

Mild steel & EN-series

Mild steel (and the tougher EN8/EN9 grades) is the workhorse. It is strong, machines cleanly, and costs less than stainless. It is the right pick for structural fasteners, machinery parts, collars and drums where the part is painted, plated or lives in a dry environment.

Where it struggles is corrosion. Left bare in a wet, humid or chemical setting, mild steel rusts, so we plate or oil it, or move up to stainless.

Stainless SS304 & SS316

Stainless resists corrosion because of its chromium content. SS304 handles most general and food-contact duty. SS316 adds molybdenum, which dramatically improves resistance to chlorides, the reason it is the default for valves, marine, coastal and chemical service.

Stainless costs more and is slower to machine, but for anything that seals a fluid or lives outdoors, it pays for itself in service life.

A quick rule of thumb

• Dry, structural, cost-sensitive? Mild steel or EN8.
• Wet, food, general corrosion? SS304.
• Valves, marine, chemical, chloride exposure? SS316.

Not sure? Tell us the application and we will recommend the grade that balances performance and cost for your part.