What is the difference between 304 and 316 stainless steel?
History of stainless steel
Stainless steel, also known as inox steel is a steel alloy. The main difference between stainless steel and ordinary (carbon) steel is that the former is not subject to corrosion when exposed to water or air, while the latter is subject to corrosion. Therefore, stainless steel is used in applications that require not only the properties of steel but also high corrosion resistance.
How is stainless steel made?
In the steelmaking process, when ordinary steel is still in a molten state, various elements are added to the ordinary steel. The added elements and the amount of these elements will change the properties of the steel. If the amount of chromium added during steel production exceeds 10.5% of the total mass of the alloy, the resulting steel alloy is stainless steel.
Why is stainless steel highly corrosion resistant?
Stainless steel contains a large amount of chromium and therefore has high corrosion resistance. This chromium reacts with oxygen in the atmosphere to form a passivation layer of chromium oxide. Since this layer is formed, oxygen in the atmosphere cannot reach the actual steel surface. This prevents metal alloys from rusting or corroding. However, to do this, not only should a sufficient amount of chromium be present, but also a sufficient amount of oxygen. As a result, stainless steel may still corrode in environments with low oxygen levels.
What is the difference between 304 and 316 stainless steel?
Simply put 304 contains 18% chromium and 8% nickel, while 316 contains 16% chromium, 10% nickel and 2% molybdenum. The addition of molybdenum helps to resist the corrosion of chlorides such as seawater and deicing salts.
How do you know that you are using 316 stainless steel instead of 304 stainless steel?
It is difficult to know by naked eyes. There are no visible differences between two identical sheet metal parts (polished or sanded in exactly the same way). That's why you need a Material Test Report (MTR) of the actual material to verify that it is 304 or 316.
What is 304 stainless steel? What is it used for?
Type 304 with chromium-nickel content and low carbon is the most widely used austenitic stainless steel. Its alloys are all variants of 18% chromium and 8% nickel austenitic alloys. Type 304 is proven to be resistant to oxidation, corrosion and durability. All of these make manufacturing and cleaning easy, preventing product contamination and providing a variety of surface treatments and appearances. Type 304 stainless steel is used for corrosion-resistant electrical enclosures, auto-forming and decoration, wheel housings, kitchen equipment, hose clamps, exhaust manifolds, stainless steel hardware, storage tanks, pressure vessels and pipes.
What is 316 stainless steel? What is it used for?
Type 316 stainless steel is austenitic chromium-nickel stainless steel and heat-resistant steel. Compared with other chromium-nickel steels, it has excellent corrosion resistance when exposed to a variety of chemical corrosive agents (such as seawater, salt solutions, etc.). The alloy contains molybdenum since 316 stainless steel, and it has stronger chemical resistance than 304. Type 316 is durable and easy to manufacture, clean, weld and surface finish. It is more resistant to solutions of sulfuric acid, chloride, bromide, iodide and fatty acids at high temperatures. In order to avoid excessive metal contamination, stainless steel containing molybdenum is required in the production of certain drugs. Most importantly, the up-front cost of Type 316 stainless steel is higher, but you can save a lot of back-end costs-especially if your enclosure is to be used outdoors.