316 stainless steel properties make it the second most widely used stainless steel after type 304. The main difference between the two is the addition of molybdenum, this adds extra corrosion and oxidation resistance.
The steel is particularly useful for areas where the anti-corrosion is a must, hence it sometimes being referred to as marine steel.
What is 316 Stainless Steel
As mentioned above, 316 stainless steel is often referred to as marine steel, it has incredible resistance to chloride corrosion. The sodium chloride present in seawater attacks the Iron molecules in steel, this causes pitting corrosion. With the addition of 2-3% molybdenum, the steel attains anti-corrosion properties surpassing type 304 stainless steel. This makes it perfect for any environment where the application requires these properties. It is perfect for marine applications, including offshore construction and coastal architectural fascias.
Even though marine applications are the most common for 316, it was originally developed for the industrial processing of pulp in the production of paper. The steel was required because the sulfur compounds present in the paper manufacturing process are very corrosive and can cause pitting similar to chloride corrosion. The manufacturing process also has excessive humidity which again accelerates the corrosion.
Other Grades of 316 Stainless steel
The base 316 steel is available in other grades which add to the properties present in it.
316L
This grade is lower in carbon and has a higher resistance to corrosion in, for instance, warm water environments. It is also better for avoiding weld corrosion.
316H
This is the higher carbon variant of 316. It is the preferred choice when it is used where elevated temperatures are present. The increase in carbon also lends it to have a greater tensile and yield strength. The austenitic structure of the material also gives this grade excellent toughness, even down to cryogenic temperatures.
316Ti
In addition to the other 316 stainless steel properties, the addition of Titanium (0.5%) gives this grade better high-temperature strength and mechanical strength. The titanium atoms stabilize the structure of the 316 at temperatures over 1472°F.
316N
Nonhardenable, higher strength than conventional 316, yet it retains good ductility, as well as good corrosion and heat resistance.
Applications for Type 316 Stainless Steel
- Pharmaceutical equipment
- Pasteurization and fermentation tanks
- Food processing equipment
- Laboratory benches & equipment
- Brewery equipment
- Boat fittings
- Chemical and petrochemical equipment
- Coastal architectural paneling
- Coastal balustrading
- Springs for the marine, oil and gas industries
- Nuts and bolts
- Chemical transportation containers
- Heat exchangers
- Mining screens
- Street Furniture
- Springs
- Medical implants
316 Stainless steel properties
Corrosion Resistance
Amongst the 316 stainless steel properties, anti-corrosion is the most important. Type 316 Stainless steel has excellent corrosion resistance, no matter the environments it is exposed to. It is however not preferred when exposed to warm seawater when it can be susceptible to pitting and crevice corrosion.
Heat Resistance
Type 316 has good resistance to oxidation when it is used in intermittent service up to 1578°F and can also be used in continuous service right up to 1697°F. The steel is not recommended when used in water-prone environments at between 797-1575°F. In those instances, it is preferable to use the 316L variant of the steel. When these conditions apply and high strength is required above temperatures of 932°F it is recommended that 316H steel is used.
Fabrication
When any stainless steel is used in any fabrication it should always be carried out using tools dedicated to stainless steel. All surfaces and tooling must be completely clean prior to use. These precautions are to avoid any cross-contamination of the stainless steel by corrosive materials such as iron which may discolor the surface of the end product.
Cold Working
Type 316 stainless steel easily roll-formed into various parts. It is also suited to stamping, drawing and heading, in all cases it is recommended to relieve any internal stresses with post-work annealing. Cold working of the metal increases it’s strength and surface hardness.
Hot Working
Any hot working processes used in standard steel can also be performed on 316 stainless steel. It is however recommended that hot working not be carried out below 1700°F. In fact the ideal temperature range for hot working it should be 2100-2300°F. It is also recommended that post-work annealing should be carried out to ensure that optimum corrosion resistance is reached.
Machinability
Like most stainless steels, Type 316 and its variants have good machinability. The machinability can be further enhanced by:
- Make sure that cut edges are kept sharp, a dull edge can cause excess work hardening.
- Cuts to the steel must be light yet deep enough to prevent work hardening.
- Use chip breakers to make sure that swarf is kept clear of the work.
- Using coolants and lubricants will make sure that heat concentration at the cutting edges is kept to a minimum.
Heat Treatment
Type 316 stainless steel cannot be hardened by heat treatment. Solution treatment or annealing can be done by rapid cooling after heating to 2012-2048°F
Weldability
Type 316 can be fusion welded to excellent standards with and without fillers. It is best to use filler rods and electrodes made from the same base metal. It is recommended that heavy welded sections be annealed post-weld. For the best performance, it is best to use grade 316Ti when it requires heavy welded sections. We also recommended not using oxyacetylene welding.
