What is Stainless Steel 304, 316, and 316L

Stainless Steel (SS), in reality, is a generic term referring to a variety of steel types. Steel is made from iron and carbon in a two-step process. Once the impurities are removed from the molten steel, the addition of chromium (Cr) and other alloying elements such as nickel (Ni) produces Stainless Steel. These elements create a corrosion-resistant product know as stainless steel.

KEY POINTS

  1. What Is The Composition Of Stainless Steel?
  2. Is Stainless Steel Good Quality?
  3. Why Does Stainless Steel Not Rust?
  4. Is Stainless Steel Rust-Resistant?
  5. What Grade Of Stainless Steel Will Not Rust?
  6. What Can Cause Rust On Stainless Steel?
  7. Does WD 40 Remove Rust From Stainless?
  8. Does WD 40 Prevent Rust?
  9. Does Vinegar Remove Rust From Stainless Steel?
  10. Do Vinegar And Baking Soda Remove Rust From Stainless Steel?
  11. Does Coca-Cola Really Remove Rust?
  12. Can Lemon Remove Rust?
  13. Does Bleach Remove Rust?
  14. Which Is Stronger, 304 Or 316 Stainless Steel?
  15. What Is The Purest Stainless Steel?
  16. What Is The Highest Grade Of Stainless Steel?
  17. How Can I Tell If My Stainless Steel Is 304 Or 316?
  18. How Long Will Stainless Steel Last?
  19. Which Is Better, Steel Or Iron Railing?
  20. What Are The Four Major Types Of Stainless Steel?
  21. What Is The Difference Between SS 316 And 316L?
  22. Is 304 Stainless Steel Good Quality?
  23. What Makes Stainless Steel Corrosion Resistant?
  24. Heat Resistance
  25. Welding Characteristics
  26. Processing – Hot Forming
  27. Processing – Cold Forming
  28. Machinability
  29. Specifications
  30. Standards

1. What Is The Composition Of Stainless Steel?

A corrosion-resistant alloy Stainless Steel is made form of iron, chromium, and, in some cases, nickel and other metals. Entirely recyclable, Stainless Steel is the "green material" of the construction sector. The actual recovery rate of close to 100% is environmentally neutral and inert. Its longevity ensures it meets sustainable construction requirements. It will not leach compounds that could modify its composition when in contact with elements like water.

2. Is Stainless Steel Good Quality?

Stainless Steel is an alloy made of several different types of metal alloys that, when combined, make for more substantial and more durable steel than when used separately. By adding and subtracting various elements to Stainless Steel, engineers have created many different varieties of the alloy, each changing the characteristics and uses of Stainless Steel. ANSI 316 Stainless Steel is a perfect alloy for use in railing systems for durability and corrosion resistance.

3. Why Does Stainless Steel Not Rust?

Stainless Steel does not rust because of the interaction between its alloying elements and the environment. It contains iron, chromium, manganese, silicon, carbon, and, in many cases, significant amounts of nickel and molybdenum. Chromium plays a dominant role in reacting with oxygen to form product film. This chromium oxide layer creates a barrier that limits oxygen and water access to the underlying metal surface. All Stainless Steel, by definition, contains at least 10 percent chromium.

4. Is Stainless Steel Rust-Resistant?

Stainless Steel gets its name "Stainless" because of its superior corrosion-resistant due to the interaction of the metal and the environment. Stainless Steel contains iron, chromium, manganese, silicon, carbon, with ANSI 316 having nickel and molybdenum added. These elements form a very thin, stable film known as the chromium oxide layer when reacting with oxygen. Being a few atomic layers thick, the film develops quickly and acts as a barrier limiting oxygen and water access to the metal surface. The result is Stainless Steel protects itself and has a very low rate of corrosion if appropriately maintained.

Passivating Stainless SteelWhy Doesn't Stainless Steel Rust?

5. What Grade Of Stainless Steel Will Not Rust?

Austenitic Stainless Steel dominant industry and comprises over 70% of total Stainless Steel production. Containing a maximum of 0.15% carbon and a minimum of 16% chromium protects against rust. The chromium combines with the oxygen to create a chromium oxide layer. This layer is corrosion resistant and prevents rust formation protecting the underlying metal. ANSI 316 performs better than ANSI 304 in outdoor or extreme locations, including chlorinated or salty environments.

6. What Can Cause Rust On Stainless Steel?

Stainless Steel can rust when the chromium oxide layer is damaged. Often this is caused by exposure to cleaners, chloride, high humidity, marine environments, and/or mechanical abrasion. Once you remove the rust on the surface, passivate the surface to recreate the protective layer on the surface. A natural process by exposing the chromium in the Stainless Steel to oxygen.

7. Does WD 40 Remove Rust From Stainless?

WD-40 can assist the process of removing rust on metals like iron, chrome, and Stainless Steel without damaging the surface or removing any coatings. It was initially designed as an anti-corrosive compound for the aerospace industry. The process is to spray it on the surface, wait approximately 10 minutes and scrub it off with an abrasive cloth.

The lubricating qualities loosen the bonds between the rust and the metal surface. Being a moisture deterrent is will also provide temporary protection from rust. The chromium oxide layer will not form while the WD-40 is on the surface. At Inline Design, we recommend if using WD-40 to remove rust, you clean the surface once you remove the rust and perform the passivation procedure.

8. Does WD 40 Prevent Rust?

Standard WD-40 will only provide temporary protection from rust and corrosion. WD-40 has a long-lasting corrosion inhibitor formula, WD-40 Specialist® Corrosion Inhibitor, an anti-rust spray designed to protect the surface for up to 1 year. Inline Design strongly recommends you clean the surface once you remove the rust and perform the passivation procedure.

9. Does Vinegar Remove Rust From Stainless Steel?

Pour a decent amount of vinegar onto a cloth or soft scrub, and rub it on the stainless surface where rust has appeared. Leave vinegar for 5 to 10 minutes on the surface. Then clean it with cold water.

Inline Design strongly recommends that you passivate the surface to create the protective layer after any rust removal technic.

10. Do Vinegar And Baking Soda Remove Rust From Stainless Steel?

Everyday household products like vinegar, baking soda, and salt make excellent cleaning agents, but together, they form a highly effective rust remover.

Alone, vinegar, baking soda, and salt all make excellent cleaning agents, but together, they form an extremely effective homemade rust remover. Adding vinegar can be combined with baking soda or salt to make a paste used to remove rust. Any vinegar and salt or vinegar and baking soda mixture will need time to break down the rust. Simply apply the paste with a soft cloth, rubbing gently in the direction of the grain. Inline Design strongly recommends that you passivate the surface to create the protective layer after any rust removal technic.

11. Does Coca-Cola Really Remove Rust?

Yes, Coca-Cola can remove rust. Coca-Cola has over 41 uses that utilize carbonic acid in the drink. The carbonic acid will eat away rust if the item is submerged for an hour or more. You will need to scrub off the Rust direction of the grain and rinse with water. Inline Design recommends that as a final step, you passivate the surface to create the protective layer on the surface after any rust removal technic.

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12. Can Lemon Remove Rust?

Lemon or Lime juice will dissolve rust when applied to the surface and left on for 30minutes. Flush with water and allow the surface to air dry. This is the same basic process when using our passivation kit, as citric acid is the active ingredient and is not harmful to the environment.

More info iconPassivating Stainless Steel

13. Does Bleach Remove Rust?

Bleach is often the go-to product when cleaning tough stains, but it is a nonstarter with Stainless Steel and rust. When you use bleach to clean rust on Stainless Steel, it will make the rust significantly worse. The sodium hypochlorite in bleach is an oxidizing agent, and rust is oxidation.

14. Which Is Stronger, 304 Or 316 Stainless Steel?

ANSI 304 and ANSI 316 have been compared since they were first developed. Both 316 and 304 Stainless Steel are good for corrosion resistance, strength, welding, and heat resistance. ANSI 316 ranks slightly more robust due to increased variation in alloying elements, Chromium, Molybdenum, and Nickel. While ANSI 304 is often less expensive, the lifecycle of the ANSI 316 with reduced maintenance costs often makes up for this cost difference. Applications with exposure to chlorinated solutions, chlorides, or marine environments ANSI 316 shows better resistance and is considered superior.

15. What Is The Purest Stainless Steel?

There are multiple grades of Stainless Steel, each with a slightly different alloy composition and slightly different physical characteristics. All steels are made from a basic iron and carbon mixture with Stainless Steel containing chromium, which gives Stainless Steel its corrosion resistance. Like standard steel, Stainless Steel can get marked up by fingerprints and grease, discolor, and eventually will rust without proper care. The difference is Stainless Steel is resilient. Stainless Steel can withstand time and abuse before showing signs of wear.

16. What Is The Highest Grade Of Stainless Steel?

Grade 316 Stainless Steel has more nickel and molybdenum in its makeup, giving it better chemical resistance to the environment. This makes it ideal for marine applications. The general mechanical properties of the two metals are mostly comparable. The addition of nickel and molybdenum makes grade 316 a more expensive alloy than Grade 304 per ounce of material.

17. How Can I Tell If My Stainless Steel Is 304 Or 316?

With over 60 different grades of Stainless Steel, 304 Stainless Steel and 316 Stainless Steel are by far the most common. Aesthetically, there is no difference. The only way to tell the difference is to test them chemically, looking for the addition of molybdenum.

18. How Long Will Stainless Steel Last?

For most purposes, copper, brass, and bronze are equivalent to Stainless Steel in durability. They're all incredibly resistant to the elements but also can be very expensive. For that sole and fundamental reason, Stainless Steel comes in at the top of the list in the construction sector. In highly corrosive conditions, the Stainless Steel corrosion rate is much slower than carbon steel and aluminum. Stainless Steel has the best balance of durability and cost-effectiveness for outdoor commercial and industrial purposes.

19. Which Is Better, Steel Or Iron Railing?

Both Stainless Steel and wrought iron Railings are unmatched for strength and durability, lasting a lifetime, giving your home or office elegance and appeal. Each having its unique benefits; there are a few things to consider in deciding which is appropriate for your application.

The strength level, versatility, and appearance determine the right option for your needs. Iron is prone to rust and softer, requiring less work to mold but requires a protective layer.

Stainless Steel is fabricated faster, requiring less energy which typically lowers the overall project costs. Aesthetically the differences are subtle, with iron Railing be more regal with an old-world elegance developing a patina over time from oxidation, while Stainless Steel has shinier and lends to a more modern look and feel, often enhancing the view.

20. What Are The Four Major Types Of Stainless Steel?

There are more than 100 different grades of stainless steel, but they can be grouped into four major types:

Austenitic

It is the most widely used with excellent corrosion and heat resistance having good mechanical properties over a wide range of temperatures. Typical uses are housewares, industrial piping and vessels, construction, and architectural facades.

Ferritic

It has very similar properties to mild steel with better corrosion, heat, and cracking resistance. Typical uses include washing machines, boilers, and indoor architecture.

Martensitic

Very hard and strong, not as resistant to corrosion as austenitic or ferritic grades. It contains approximately 13% chromium and is used to make knives and turbine blades.

Duplex

A composite of both austenitic and ferritic stainless steel, which makes it both strong and flexible. Typical uses include paper, pulp, shipbuilding, and petrochemical industries, with new grades being developed for a broader range of applications.

21. What is the Difference Between SS 316 and 316L?

Grade 316 falls into the Austenitic grade and is the most widely known and specified grade of stainless steel on the market today. It provides superior levels of corrosion resistance, excellent impact toughness down to very low temperatures, is non-magnetic in nature, and is relatively easy to fabricate.

It is the standard molybdenum-bearing grade, second in overall volume production to 304 amongst the austenitic grades of stainless steel. The molybdenum gives 316 better overall corrosion resistant properties than Grade 304, notably higher resistance to pitting and narrow openings corrosion in chloride environments.

Grade 316L, the low carbon version of 316 and has very high immunity from sensitization (grain boundary carbide precipitation). It is extensively used in the oil, gas, and chemical industries because of its cost-effective corrosion resistance and ease of fabrication.

At elevated temperatures, 316L stainless steel offers higher creep, stress to rupture, and tensile strength than chromium-nickel austenitic stainless steel. These alloys may be considered for a wide variety of applications where one or more properties are essential.

22. Is 304 Stainless Steel Good Quality?

Grade 304 stainless steel is the most common grade of austenitic stainless steel because of its many uses in industrial and kitchen applications. Historically it has been known as 8/18 stainless steel.

ANSI 304 contains high nickel content, typically between 8% and 10.5% by weight, and a high amount of chromium at approximately 18% to 20% by weight. Historically it has been known as 8/18 stainless steel.

Other significant elements include manganese, silicon, and carbon. The remainder of the chemical composition is primarily iron. It is a highly heat-resistant grade and offers good corrosion resistance.

Chemical Properties
C Mn Si P S Cr Mo Ni N

316
(S31600)

0.08
max

2.0
max

0.75
max

0.045
max

3.0
max

min: 16.0
max: 18.0

min: 2.0
max: 3.0

min: 10.0
max: 14.0

0.10
max

316L
(S31603)

 0.03
max		 2.0
max		 0.75
max		 0.045
max		 3.0
max		 min: 16.0
max: 18.0		 min: 2.0
max: 3.0		 min: 10.0
max: 14.0		 0.10
max

304
(S30400)

 0.08
max		 2.0
max		 0.75
max		 0.045
max		 0.03
max		 max: 20.0 Min: 5
max: 8.0		 0.10
max
Mechanical Properties
Grade Tensile strength ksi (min) Yield strength 0.2% ksi (min) Elongation % Hardness (Brinell (max) Hardness (Rockwell B) Max
316
(S31600		 75 30 40 217 95
316L
(S31603)		 70 25 45 217 95
304
(S30400)		 80 31 70 123 70
Physical Properties
Density lbm/in3 Thermal Conductivity
(BTU/h ft F)		 Electrical Resistivity
(in x 10-6)		 Modulus of Elasticity
(psi x 106)		 Coefficient of
Thermal Expansion
(in/in)/F x 10-6)		 Specific Heat
(BTU/lb/F)		 Melting
Range (F)
316
(S31600)		 0.29 at 68˚ F 100.8 at 68 212˚ F 29.1 at 68˚ F 29 8.9 at 32 - 212˚ F 0.108 at 68˚ F 2500 to 2550
304
(S30400)		 0.285 at 68˚ F 9.4 at 68 212˚ F 28.3 at 68˚ F 28 9.2 at
68-212˚ F		 0.12 at 68˚ F
2,550 to 2,650

23. What Makes Stainless Steel Corrosion Resistant?

The ability of stainless steel to resist corrosion is related to the chromium content in the steel. The chromium is the alloy element that endows stainless steel with its corrosion resistance.

  • 316 is generally more resistant than 304 in a range of atmospheric environments and many corrosive media due to the molybdenum increased chromium content.
  • Subject to pitting and crevice corrosion in warm chloride environments and stress corrosion cracking above about 122°F (50°C).
  • Considered resistant to potable water with up to about 1000mg/L chlorides at ambient temperatures, reducing to about 500mg/L at
  • 140°F (60°C).
  • 316L is usually regarded as the “marine grade stainless steel” – but is not resistant to warm seawater.
  • 304 can withstand corrosion from most oxidizing acids.

24. Heat Resistance

There are four design factors that engineers consider when choosing materials to serve in elevated temperatures. These design factors include service life, allowable deformation, environment, and cost.

  • High-temperature oxidation resistance in intermittent service to 1600°F (870°C) and in continuous service to 1700°F (925°C)
  • Grade 316L is more resistant to chrome and carbon being drawn out and reacting with the atmosphere
  • Use of 304 in the 425-860 °C range is not recommended if subsequent aqueous corrosion resistance is important

25. Welding Characteristics

Austenitic stainless steel is readily welded, weld metal and HAZ cracking can occur. Weld metal solidification cracking is more likely in fully austenitic structures which are more crack sensitive than those containing a small amount of ferrite. The beneficial effects of ferrite has been attributed largely to its capacity to dissolve harmful impurities in the weld.

  • Excellent weldability by all standard fusion methods, both with and without filler metals.
  • Heavy welded sections in Grade 316 require post-weld annealing for maximum corrosion resistance, this is not required for grade 316L.
  • ANSI 304 does not normally require post welding annealing

26. Processing – Hot Forming

Hot forming has numerous benefits in the forming process. The benefits can increase accuracy, Prevent of cracking, allow for formation of complex shapes, tighter radii and avoid material thinning.

  • ANSI 316 recommended maximum forging temperature between 2100°F and 2300°F
  • ANSI 316 should not be forged below 1700°F (927°C)
  • Corrosion resistance is obtained if the forgings are given a final anneal.
  • ANSI 304 forging is best with uniform heating to 2100°F (1149°C)

27. Processing – Cold Forming

Cold forming is also known as cold working. The technical definition is a metalworking process in which the shaping occurs below its recrystallization temperature. This allows Steel manufacturers to use high-speed processes to produce large amounts of products quickly, consistently, and cost-effectively.

  • 316/316L types being extremely tough and ductile, can be readily cold worked such as roll form, swaging, cold heading, deep drawing, bent, etc., without difficulty
  • Severely cold-formed parts should be annealed to remove stresses
  • 304 becomes slightly magnetic

28. Machinability

Austenitic Grade Stainless Steel is more prone to work hardening, and there is a need to invest in special tooling. One solution is using sharp tooling and replacing tools the moment they start to wear down or work at slower speeds with higher feed rates.

  • Type 316/316L is somewhat more difficult to machine than Type 304 because of its toughness
  • 316/316L machines with chip characteristics that are tough and strong
  • 304 cuts should be light but deep enough to prevent work hardening by riding on the surface of the material
  • Chip breakers and curlers are advised
  • As large a tool as possible with significant amounts of cutting fluid should be used to prevent vibration
  • Heavy positive feeds at low speeds should be considered since 316/316L work hardens rapidly

29. Specifications

ASTM/ASME ASTM A240

30. Standards

MATERIAL UNS EURONORM AFNOR DIN:
316 316L UNS S31600 / S31603 X1 CrNiMo 17 12 2 / X3 CrNiMo 17 12 2 Z 6 CND 17-11
1.4401 / 1.4404
304

UNS S30400

 X5CrNi18-10

Z 6 CN 18 09

1.4301