MEAM.Design - Materials - Stainless Steel (304)
Instron Testing Video and Data
Tension Testing (mov) Δ - Excel Data
Containing at least 10% Chromium by mass, these steel alloys usually have higher strength and much improved resistance to corrosion, but are typically more expensive and harder to machine than regular carbon steels. We will focus on two main families of stainless steels:
- With less than 0.15% Carbon and at least 16% Chromium, these non-magnetic alloys are the most commonly found stainless steels. The three most popular variants are:
304 - The most common grade of stainless, also known as 18/8 (18% Chromium, 8% Nickel). 304 is relatively inexpensive, is weldable, but is difficult to machine. UTS = 73 kpsi, Y = 31 kpsi.
303 - The addition of sulfur and phosphorus to 304 results in significantly improved machinability, but this alloy is difficult to weld. 303 is also considerably more expensive than 304 (approx. 4x). UTS=90kpsi, Y=35kpsi.
316 - Known as "marine grade" stainless, the addition of Molybdenum gives 316 improved corrosion resistance, especially in salt-water environments. The machinability is similar to 304, and the price point typically falls between 304 and 303. UTS=90kpsi, Y=60kpsi (note- the higher yield strength makes 316 significantly harder to bend).