Two of the most common grades of austenitic stainless steel are 304 (1.4301) and 316 (1.4401). In appearance the 2 are indistinguishable and the few tests to differentiate between them include either hazardous chemicals (in the case of a molybdenum drop test) or expensive equipment (such as positive material identification).
The 2 grades though have very unique characteristics due to their chemical composition and care should be taken when selecting which type is best suited to your application.
304 stainless steel vs 316
Cost
The cost of stainless steel is largely dependent on the alloys that are present in their composition. All stainless steels require a minimum of 10.5% chromium and they are alloyed with iron which makes up a large proportion of their final makeup. The various other elements present though have an impact on the properties and characteristics and ultimately, cost.
316 contains a minimum 2.0% molybdenum which makes it much more corrosion resistant than 304 however, as it is a more expensive element, generally makes 316 a more expensive grade of metal.
Magnetism
Both grades are austenitic which means that they do not have magnetic properties however cold working can have an effect on this. When the stainless steel is formed or cut, there will be a slight increase in their magnetic properties although this is only minor.
Chemical composition
| Grade | C | Si | Mn | P | S | N | Cr | Ni | Mo |
| 304 | 0.07 | 1 | 2 | 0.045 | 0.015 | 0.1 | 17.5 - 19.5 | 8.0 - 10.5 | - |
| 316 | 0.07 | 1 | 2 | 0.045 | 0.015 | 0.1 | 16.5 - 18.5 | 10.0 - 13.0 | 2.0 - 2.5 |
Corrosion resistance
Stainless steel as a family of metals is very corrosion resistant but with the addition of molybdenum into 316, this increases the grades ability to withstand harsh environments. Often referred to as marine grade, 316 is suitable for use in environments that are more aggressive than ambient although care should still be taken to clean the metal regularly to prolong its service life.
Applications for 304 Stainless Steel
Most of the applications of stainless steel 304 are attributed to its high concentration of Chromium which gives the alloy excellent corrosion resistance. These applications include:
In making kitchen appliances like refrigerators and dishwashers
Used to make heat exchangers
Used in commercial food processing equipment and kitchen fittings like sinks and splashbacks
Used to make saucepans, cutlery and flatware
Architectural paneling
In making nuts, bolts, screws and nuts
Used in making brewery, food, and pharmaceutical production equipment
Generally, Stainless steel is used in applications that would corrode standard carbon steel.
Applications for 316 Stainless Steel
Stainless steel 316 was originally developed for use in paper mills. It is now commonly used in various applications which include:
Making food, chemical and petrol production and processing equipment
Construction of laboratory benches and equipment
Architectural panelling in the coastal region
Boat fitting
Mining screens
Kitchenware, sanitaryware and troughs
Tubing
Medical implants
Stainless 316 has better corrosion resistance than Stainless steel and often exhibits better strength at high temperatures.
