Stainless Steel Alloy 316

Stainless steel alloy 316 has a couple of different designations. Grade 316 is also known as alloy 1.4401, while 3164L is known as 1.4404. This austenitic alloy is bypassed by stainless steel alloy 304 for commercial importance.

Molybdenum is the ingredient that gives stainless steel alloy 316 its remarkable resistance to corrosion. While it is highly resistant to corrosion and is often considered suitable as a “marine” stainless steel, it does not do well when exposed to saltwater in warmer temperatures. It will also pit and experience corrosion around crevices when exposed to warm chloride.

As with 304L, 316L is simply the version of stainless steel alloy 316 that contains a lower percentage of carbon. This makes it immune to sensitization, also known as grain boundary carbide precipitation. 316L is also ideally suited to welded applications requiring a 6mm or more, heavy gauge.

There are even more variations of alloy 316; grades 316Ti and 316H. Grade 316Ti is a stabilized stainless steel alloy, while 316H contains a higher percentage of carbon. The higher percentage of carbon allows 316H to be used in applications where exposure to high temperatures is likely to occur.

All versions of stainless steel alloy 316 have the same Rockwell Hardness B score of 95. The difference appears in the tensile strength and proof stress scores, with 316L having lower scores in both those areas.

Any fabrication of an application made from stainless steel should only use tools used exclusively for fabricating stainless steel. It is also extremely important that any surface or tool that comes in contact with stainless steel be cleaned prior to fabrication. Failure to clean can cause cross contamination by other metal which are more apt to experience corrosion, thereby promoting discoloration of the surface of the stainless steel item.

Cold working of stainless steel 316 is an excellent way to increase the hardness and strength of this particular alloy. Stamping and heading, as well as drawing are all possible with SST-316, however to relieve internal material stress annealing should be done once the cold working has finished.

Hot working of stainless steel alloy 316 can be easily done as long as proper temperatures of 1149-1260 C are maintained during the work. If the temperature falls below 927 C all hot work should cease until the temperature can be raised to the ideal ranges.

Heat treatment does not work on alloy 316. To guarantee the best corrosion resistance annealing by rapid cooling should be done once the work has ended.

For machinability 316 is excellent. It is important that chip breakers be used, cutting edges are sharp and that abundant amounts of lubricants or coolants are used to avoid the cutting edges becoming overheated.

Some of the applications to use stainless steel alloy 316 are: coastal paneling, balustrades and boat fittings, laboratory furnishings and equipment, as well as equipment used in chemical and petrochemical environments. It can also be found in brewery and food processing equipment, springs, nuts, bolts and even medical implants.

For more information about the actual chemical composition of Stainless Steel Alloy 316.

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