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What Are the Properties of 303-304-316 Stainless Steel


One of the great things about stainless steel is that it comes in many product forms and grades.  This gives manufacturers a variety of options to choose from.  The great news is that no matter what application you are using stainless steel for, there’s probably a grade that can meet your specifications.

Of course, there’s another side of the coin.  For many manufacturers, it’s hard to pick from all of the many alternatives.  For example, how can you tell the difference between grades such as 303, 304 or 316?  Are they really that different or are they basically interchangeable?

Any experienced metalworker will tell you that every grade of stainless steel is unique. 303 and 304 may sound like they are just slight variations on the same basic metal, but the reality is they have very different properties.  The same thing applies to 316 and every other type of stainless steel.  That’s why it’s imperative that you do your research and give proper consideration before making a final grade selection for a particular application.

303, 304 and 316 are all part of the same stainless steel family

It’s true that every type of stainless steel with the 3xx moniker is part of the same series of austenitic stainless steel.  That means there are certain chemical properties that they all share.

The 300 series of stainless steels is characterized by its chromium (approx. 18 to 30%) and nickel (approx. 6 to 20%) content, as they are the major alloying elements used in their chemistries.  Broadly speaking, these stainless steels are recognized by their ability to withstand high temperatures while retaining their strength, being easy to maintain and offering excellent corrosion resistance.

Stainless steels are generally divided into five categories.  In addition to austenitic, there’s ferritic, martensitic, duplex and precipitation hardening.  The differences are based on their distinct microscopic crystalline structures, each of which lends the steel a specific metallurgical profile.

Austenitic stainless steels are non-magnetic steels with low carbon levels.  They generally have excellent formability and weldability with good toughness, even at extremely low temperatures.  At the molecular level, austenitic stainless steels can be recognized by their face-centered cubic (FCC) crystal structure.  The grain is formed in this way because of the nickel alloying agent.

While austenitic stainless steels cannot be heat treated, it is possible to cold work the metal for better hardness, strength and stress resistance.  In addition to the 300 series, the 200 series is also austenitic in nature.  In contrast to the 300 series, these stainless steels have much lower nickel content but have nitrogen added.  It’s important to note that austenitic steels tend to be more expensive than ferritic stainless steels, but because of the increased durability and corrosion resistance the price is often worth it.

What are the characteristics of 303 stainless steel bar?

Alloy 303 was specifically developed for improved machinability and thus is an excellent choice for parts that need extensive machining.  As long as extreme environments are avoided the alloy offers good corrosion resistance.  This is because sulfur has been added to boost its machinability, meaning it won’t be as resistant to corrosion as other 300 stainless steels.  Its formability is also considered excellent, as well as its toughness, though its sulfur content does somewhat affect the latter.

The types of applications and industries where you are likely to find 303 stainless steel are those that require heavy machining.  The types of parts include nuts and bolts, fittings, gears, screws, switchgear, bushings, shafts, pump/valve parts and more.  Industries that feature this alloy include aerospace, automotive and architecture.

What are the characteristics of 304 stainless steel bar?

Alloy 304 is the most commonly used stainless steel.  It is very similar in chemistry to 303, the main difference being the lack of sulfur.  This means it is not as easily machinable, but it offers improved corrosion resistance and toughness.  It still provides excellent formability when compared with many other types of stainless steel, as well as ease of fabrication and weldability.

Because corrosion resistance is one of the main benefits of stainless steel, it’s worth taking a closer look.  304 can withstand many corrosive environments.  It is generally safe from pitting and crevice corrosion, excepting exposure to warm chlorides, and it is resistant to stress corrosion cracking up to 60°C.

As the most common of the stainless steel alloys, it can be found in a variety of industries. Examples include kitchen appliances, utensils, chemical containers, food and beverage processing, heat exchangers, springs, automobile parts, construction, architectural fixtures and paneling, aircraft and more.

What are the characteristics of 316 stainless steel bar?

The main things that distinguish 316 stainless steel from 303 and 304 are the addition of molybdenum as an alloying agent and a higher nickel content.  This combination means a significant boost to 316’s corrosion resistance, making it perfect for marine and chloride environments.  Other benefits include improved temperature, tensile, creep and stress-rupture strengths.  This alloy also offers good formability and weldability.

Alloy 316 benefits include durability and ease of fabrication.  It is extremely hygienic and easy to weld and finish.  Its corrosion resistance extends to protection against sulfuric acid, chlorides, bromides, iodides and fatty acids.  This is why certain pharmaceuticals must be manufactured with metal equipment made from 316.

Other applications for 316 stainless steel include food and beverage equipment, in particular when corrosion resistance is a high priority, as well as chemical equipment, laboratory benches, pulp and paper equipment and pollution controls. Additionally, you can find 316 in boats, heat exchangers, evaporators, textile plants and liquid tanks.

Your technical services provider

If you need information on which type of stainless steel alloy is right for your particular application, you should consult with the experts at Clinton Aluminum. Our team of professionals is dedicated to working with clients to help find the perfect material for the job at hand.  Our goal is always to be more than an equipment supplier, but to help our customers at every step of the procurement process.

Contact one of our friendly and knowledgeable associates today to learn more.

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