304 Vs 316 Stainless Steel, What is difference?
What is stainless steel 304 or 316? What are the differences between them, and what does each have to offer? The ASTM designation 304 and 316 both have their pros and cons. It’s important to know what you choose before buying a set of new pans or selecting a company for an upcoming metal project.
What is 304 stainless steel?
304 stainless steel is an alloy with the optimum combination of chromium and nickel, making it the most versatile of all stainless steel. It offers excellent corrosion resistance to various environments, including coastal atmospheres, industrial atmospheres, and a wide range of pH levels. It has incredible high-temperature strength and maintains its toughness at elevated temperatures.
What is 316 stainless steel?
316 stainless steel is an alloy that contains a higher percentage of chromium, making it almost twice as resistant to corrosion as the 304 .316 is also known for easily meeting the requirements of ASTM A53 and other industries. It is less expensive than 304 and offers comparable corrosion resistance, strength, and toughness in most applications.
304 VS 316 stainless steel
304 Vs 316 Stainless Steel #1: Chemical Composition
304 and 316 stainless steel are austenitic stainless steels, The 304 and 316 differ in composition. 304 is an austenitic alloy with a chromium/nickel mix of approximately 10/90. This means that a higher amount of nickel is added to the alloy, which produces a slightly harder, less elastic steel.
The chemical composition of 304 and 316 stainless steel mainly includes:
304 Stainless Steel
316 Stainless Steel
Iron (Fe) :
66%
65%
Chromium (Cr) :
18%
16% – 18%
Nickel (Ni)
8%
10% – 14%
Manganese (Mn) :
2%
2% – 3%
Silicon (Si) :
1%
< 2%
Phosphorus & Sulfur
< 0.03%
< 0.03%
304 Vs 316 Stainless Steel #2: Physical Properties
The physical properties of each type are different. The 304 is a soft, low-carbon steel that can be easily worked. It has a balanced combination of strength, toughness, and excellent Weldability.
The 316 is a hard, high-carbon steel that cannot be thoroughly worked without danger of cracking. It is also very difficult to weld and should only be used in joint parts that are very small in size or do not require heavy loads. It has a high toughness and excellent wear and tear resistance, making it suitable for knife blades and car parts applications.
Each type has its benefit according to your need, but you must know what you choose before buying or choosing a company for an upcoming metal project.
The physical properties of 304 and 316 stainless steel
304 Stainless Steel
316 Stainless Steel
Density :
7.93 g/cm³
8.00 g/cm³
Melting Point :
1400-1450 ℃
1370-1400 ℃
Thermal Expansivity :
17.3×10^-6/℃
16.5×10^-6/℃
Heat Conductivity :
16.2-24.9 W/(m·K)
16.2-21.5 W/(m·K)
Electric Conduction ：
1.45×10^6 – 1.6×10^6 S/m
1.29×10^6 – 1.4×10^6 S/m
Magnetism :
Yes
No
304 Vs 316 Stainless Steel #3: Mechanical Properties
The mechanical properties of stainless steel include strength, hardness, toughness, ductility, plasticity and other indicators. Different types of stainless steel have different mechanical properties,
The following are the mechanical properties of 304 and 316 stainless steel
304 Stainless Steel
316 Stainless Steel
515 MPa
590 MPa
Yield Strength :
1400-1450 ℃
1370-1400 ℃
Hardness :
17.3×10^-6/℃
16.5×10^-6/℃
Elongation :
16.2-24.9 W/(m·K)
16.2-21.5 W/(m·K)
Elasticity Modulus ：
1.45×10^6 – 1.6×10^6 S/m
1.29×10^6 – 1.4×10^6 S/m
304 Vs 316 Stainless Steel #4: Heat Resistance
The heat resistance of 304 and 316 stainless steel is also different. 304 is more resistant to heat than 316 because of its higher chromium content and easy Weldability. It can be used in a wide range of applications, even in places with extreme temperatures, although it can be used at lower temperatures than 316.
In contrast to the easy welding of 304, the hardening treatment of 316 stainless steel makes it very difficult to weld. Even an incorrectly shaped piece will result in difficulty before it breaks. Therefore, parts made up of 316 should be welded by professionals only as they usually break when welded by amateurs or hobbyists.
304 Vs 316 Stainless Steel #5: Weldability and formability
There are some differences between 304 and 316 as they are welded. The flatness of the surface of the 304 is usually better than that of 316 due to its high chromium content. However, there is a tendency on the part of 316 to be harder and require more force. In addition, in stamped or forged parts, it’s easy to create flaws in 316, especially when the forging temperature is relatively high.
Welding alloys with higher carbon content than pure steel can cause cracking in places with too much tension, which can also occur with 304. This means that if you’re welding a piece made up of 304, you should use TIG welding to ensure it doesn’t crack during welding. If you’re welding a piece made of 316, direct MIG welding is recommended because it makes it more likely that the weld will hold up to higher loads.
Therefore, if you’re welding a part of either 304 or 316, use TIG welding, not MIG. Select the appropriate TIG or MIG wire if you wish to use an AWS welder. When welding with TIG, ensure that your anodizing work doesn’t cover it too much so that the weld is hidden behind the anodized surface. Otherwise, the weld won’t stand up to the higher loads.
304 Vs 316 Stainless Steel #6: Durability
304 is more resistant to oxidation than 316 because of its higher chromium content. Therefore, 304 is better for exterior applications, even though corrosion is a problem in seawater. This means that 316 should be used when corrosion in marine environments is a problem.
Due to its higher carbon content, the 316 can be easily oxidized by atmospheric oxidation. Therefore the 316 may corrode if not grounded during forming or welding. The 316 can also rust if the atmosphere is humid and salty, which makes it unsuitable for exterior purposes.
The 304 stainless steel can be easily machined due to its high chromium content and relatively low carbon content, while the 316 is more difficult to machine due to its high carbon content and its hardening treatment. This hardness makes it more difficult to be worked with common tools like drills or saws; it also provides less play when being set in a jig, which leads it to break more easily in the workpiece than in 304. In addition, there is a tendency for the 316 stainless steel edge parts to crack when welding, which further hinders them from being machined by machines.
Therefore, 304 is a better choice for large parts and manual machining as it’s easier to machine. If you are working with a machine or have decided to use a machine, make sure that the material you’re working with is 316 (or even 316L).
The high carbon content of the 316 stainless steel makes it less suitable for welding interiors than 304. However, it can be used by professional welders safely due to its hardening treatment and heat resistance. The hardening treatment also makes it less susceptible to creep, meaning that, in other words, it’s more durable.
304 Vs 316 Stainless Steel #7: Corrosion Resistant
304 stainless steel has superior corrosion resistance, can resist the erosion of general atmosphere, water, acid, alkali and salt and other corrosive media at room temperature.
Its corrosion resistance mainly comes from the 18% chromium element contained in it, these chromium elements will react with oxygen in the air to form a dense chromium oxide film (Cr2O3), which can effectively prevent further oxidation and corrosion of steel.
Compared with 304 stainless steel, 316 stainless steel in the chloride ion medium corrosion resistance is better, can resist chloride corrosion and pitting corrosion and so on. In addition, 316 stainless steel also has good acid resistance, alkali resistance and high temperature resistance, can be used in more demanding corrosion environments.
304 Vs 316 Stainless Steel #8: Applications
304 Stainless Steel Application
304 stainless steel is one of the most common stainless steels. It has excellent corrosion resistance, high temperature resistance and good processing performance, so it is widely used in the following fields:
Architectural decoration: 304 stainless steel surface smooth, corrosion resistance, is widely used in indoor and outdoor decoration, stair handrails, wall decoration, elevator interior installation, etc.
Food processing industry: 304 stainless steel has excellent corrosion resistance and hygiene, so it is widely used in food processing equipment, kitchen utensils, tableware, etc.
Medical instruments: 304 stainless steel has excellent biocompatibility and corrosion resistance, so it is widely used in the manufacture of medical instruments, surgical instruments, surgical implants, etc. Mechanical manufacturing: 304 stainless steel excellent strength and corrosion resistance, is widely used in the manufacture of various mechanical parts, bearings, valves and so on.
Petrochemical, chemical and Marine engineering: 304 stainless steel can withstand high temperature, high pressure and corrosive media corrosion, so it is widely used in petrochemical, Marine engineering, chemical equipment and other fields.
Automobile, train and other transportation field: 304 stainless steel corrosion resistance and strength make it become an important part of cars and trains, such as exhaust pipe, doors, roof, etc.
316 Stainless Steel Application
316 stainless steel is a kind of steel with good corrosion resistance and high temperature resistance, widely used in the following fields:
Chemical industry: 316 stainless steel can resist the corrosion of many chemicals, so it is used in the chemical industry to manufacture storage tanks, pipes, valves and other equipment.
Food processing industry: 316 stainless steel is one of the commonly used materials in the food processing industry, used for the manufacture of containers, equipment, pipeline, etc.
Medical instruments: 316 stainless steel for its corrosion resistance, high strength and high temperature resistance properties, used in the manufacture of medical instruments, surgical tools, surgical implants, etc.
Ship construction: 316 stainless steel has good corrosion resistance in sea water, so it is widely used in ship construction and ocean engineering.
Construction industry: 316 stainless steel with high strength, beautiful, corrosion resistance and other characteristics, is widely used in building decoration, building components, indoor furniture and other fields.
Cosmetic packaging: Cosmetic bottles, powder boxes, lipstick tubes and other cosmetic products made of 316 stainless steel are exquisite in appearance and durable, which can meet the requirements of consumers for beauty and quality.
Author
Gavin Leo is a technical writer at Aria with 8 years of experience in Engineering, He proficient in machining characteristics and surface finish process of various materials. and participated in the development of more than 100complex injection molding and CNC machining projects. He is passionate about sharing his knowledge and experience.