Stainless steel is one of the most commonly used metals in the world. Manufacturers and builders use it for a wide range of purposes, as it's implemented in the construction, automotive, HVAC, household goods industries, and many others.
The main reason stainless steel is so popular is its chemical and corrosion resistance. 304 stainless steel holds up well against acids, moisture, chemicals, bases, organic compounds, and many other potential hazards. Like all stainless steel grades, 304 stainless steel can resist these things because of a passivation layer, but more on that later.
If you're curious whether or not 304 stainless steel is the right grade for you, you've come to the right place. This article will delve deeper into what 304 stainless steel is, how it's made, where it's used, and its chemical compatibility. That way, you can know if it will hold up in your workplace or if you need to go a different route.
What is 304 Stainless Steel?
UNS S30400, better known as type 304 stainless steel, is an austenitic metal used in the steel alloy industry. 304 is the most common type of stainless steel worldwide, and roughly 50% of all stainless steel materials are 304 stainless steel.
One of the reasons that 304 stainless steel is so popular is because it's available in a variety of different forms. You can get 304 in flat sheets, rolls, shaped wire, slit coil, and many other forms. This makes it one of the most versatile stainless steel grades, further boosting its popularity.
Common Applications For 304 Stainless Steel
As we said before, 304 stainless steel is the most popular type of stainless steel in the world. It is used in nearly every industry that relies on metal or steel alloys, including the following:
The Medical Field
Many of the instruments and equipment used in the medical field, such as scalpels, bedpans, medical implants, and more are made of 304 stainless steel. Safety equipment, such as gurneys, trays, and sanitation equipment are also made of 304 stainless.
Construction
Construction is perhaps where 304 stainless steel gets the most widely used. Everything from sheet metal used in HVAC ductwork to support beams to scaffolding is made of stainless steel.
Automotive Industry
Stainless steel is being somewhat replaced by aluminum, but it's still a popular material in the automotive industry. It is commonly used to make trim pieces, hoses, safety features, and sometimes the entire vehicle frame.
Gas and Oil
Because of how demanding the gas and oil industries are, stainless steel filters are often necessary during the filtration process. Certain residential filters also utilize a stainless steel frame in their construction.
Household Goods
If you look on the bottom of your sauce pan or skillet, you'll notice that most of the high-quality kitchenware you have says stainless steel. In most cases, that means it's made of 304 stainless. 304 is commonly used because of its durability and stain resistance.
Hardware
Finally, screws, nails, bolts, nuts, washers, and many other pieces of hardware are made of 304 stainless steel. This helps them hold up better to the elements and makes them approved for outdoor use.
Different Corrosion Factors of Stainless Steel
As we said before, one of the main reasons that stainless steel, particularly 304, is so popular is because of its corrosion resistance. This is because of what 304 stainless steel contains, as well as how it's created.
304 stainless steel contains between 8% and 11% nickel, which makes it resistant to organic acids, such as phosphoric acid, sulfuric acid, acetic acid, nitric acid, and others. 304 also contains 18% to 19% chromium, which helps it hold up well against oxidation. Because it holds up well against oxidation, stainless steel is resistant to rust and is a good option for use in salty or wet environments.
As with all stainless steel grades, 304 stainless also possesses a passivation layer of chromium oxide. This layer then oxidizes when the surface of the stainless steel gets exposed to oxygen, thereby protecting the surface. The beautiful thing about the passivation layer is that it's self-sustaining, which means it never wears off.
Potential Problem Areas
In general, 304 stainless steel has very few weaknesses when it comes to corrosion. However, one potential problem area is when the steel gets exposed to chlorides. Pitting and crevice corrosion can happen in these instances, which means you should keep stainless steel away from:
- Potassium chloride
- Ammonium chloride
- Sodium hydrochloride
- Mercuric chloride
- Ethyl chloride
- Chlorine
- Other forms of chloride
Another potential problem area for stainless steel is when they are exposed to certain types of acids. While 304 holds up especially well against most acids, including nitric acid, chromic acid, and nitrous acid, it doesn't do so well against others, including:
- Hydrochloric acid
- Acetic acid
- Hydrochloric acid
- Hydrofluoric acid
- Sulfuric acid
Resistance to Heat
In addition to its resistance against certain chemicals and acids, 304 stainless steel is also resistant to heat. In fact, you can continuously use 304 stainless steel in temperatures as high as 800 degrees Fahrenheit. Additionally, if your stainless steel is going to be in and out of the heat, it can sustain intermittent temperatures of up to 1600 degrees Fahrenheit.
Stainless steel's resistance to heat is because of the combination of nickel and chromium used in its design. Stainless steel is also treated with a post-weld heat treatment, further adding to its strength and durability in extreme temperatures.
The Chemical Resistance of Stainless Steel
Finally, stainless steel is highly resistant to other chemicals aside from acid. This includes a wide range of both strong and weak bases, regardless of temperature or environment. Several bases and organic compounds that 304 stainless steel stands up especially well against include:
- Methyl ethyl ketone
- Sodium carbonate
- Potassium carbonate
- Magnesium sulfate
- Magnesium nitrate
- Sodium borate
- Epsom salts
- Ferrous sulfate
However, while stainless steel is resistant to most bases, solvents, and compounds, you should be cautious about using it around sodium hypochlorite. This, along with certain acids, can cause cracking and corrosion, regardless of how strong your 304 stainless steel is.