304 vs 316 stainless steel, what is the difference?

When choosing stainless steel that has to bear corrosive atmospheres, austenitic stainless steel is recommendable. Owning excellent mechanical properties, the high amounts of chromium and nickel in austenitic stainless steels also offer distinguished resistance of corrosion. Besides, many austenitic stainless steels are formable and weldable.

Two of the most commonly used types of austenitic stainless steel are types 304 and 316. This blog will show the difference between 316 and 304 stainless steel to decide which type is proper for your project. Follow up to discover the difference between 304 vs. 316 stainless steel.

What Are Stainless Steel 304 And 316?

304 stainless steel is the most ordinary stainless steel. The steel consists of both nickel (between 8% and 10.5%) and chromium (between 18% and 20%) metals as the primary non-iron elements. 304 is austenitic stainless steel. It is less thermally conductive and electrically than carbon steel and is substantially non-magnetic. It has a higher resistance of corrosion than regular steel and is vastly used because of the softening in which it is formed into many different shapes.

The composition was formulated by W. H. Hatfield at Firth-Vickers and was sold under the marketing name “Staybrite 18/8” in 1924.

SAE International outlines it as a component of its SAE steel levels. It is widely noted as A2 stainless steel in conformity with ISO 3506 for fasteners outside the U.S. It is known as 18/8 stainless steel in the trading cookware field. It is UNS S30400, in the unified-numbering system. The corresponding Japanese type of this substance is SUS304. It is also laid down in European standard1.4301.

Type 316 Stainless Steel: The second most ordinary austenitic stainless steel is Grade 316. The supplement of 2% molybdenum offers higher acid resistance and pinpointed corrosion caused by chloride ions. Low-carbon editions, for instance, 316L or 304L, have carbon substances below 0.03% and are used to prevent corrosion problems caused by soldering.

304 vs 316: Alloy Designations

Stainless steel 304 and 316 also match the following standard specifications and designations:

Grade	Stainless Steel 304	Stainless Steel 316
Euronorm	1.4301	1.4401
UNS	S30400	S31600
BS	304S15 / 304S16 / 304S31	316S31
EN	58B	58H

304 vs 316: Alloy Composition

Both Stainless steel grades, 304 and 316, have its components; let us see the average elements’ differences.

Element	Stainless Steel 304	Stainless Steel 316
Carbon (C), %	Max 0.08	Max 0.08
Chromium (Cr), %	18.0~20.0	16.0~18.0
Manganese (Mn), %	Max 2.0	Max 2.0
Nickel (Ni), %	8.0~10.5	10.0~140.
Phosphorus (P), %	Max 0.045	Max 0.045
Sulphur (S), %	Min 0.03	Max 0.03
Silicon (Si), %	1.00	1.00
Molybdenum (Mo), %	/	2.00~3.00
Iron (Fe), %	Balance	Balance

The role of these metal elements:

Chromium – Increases hardness, tensile strength, toughness resistance to wear, abrasion, hardenability, scaling at elevated temperatures, and corrosion resistance.
Nickel – Increases hardness and strength without sacrificing toughness and ductility.
But the supplement of alloy features such as molybdenum can produce subtle, but significant, differences:
Molybdenum – Increases hardness, strength, toughness, hardenability, and strength at elevated temperatures and creep resistance.

304 vs 316: Corrosion Resistance Composition

Since Molybdenum (Mo) is included in SS316, Molybdenum can develop the rallying resistance and is, for that reason, more corrosion resistance than SS304. So SS316 more convenient to chemical plants and Offshore buildings where vastly corrosive environments.

304 vs 316 Stainless Steel: Physical Properties

To know the physical properties for both 304 vs. 316 stainless steel alloys, look at the following table.

Property	Stainless Steel 304	Stainless Steel 316
Density	8.00g / cm³	8.00g / cm³
Melting Point	1450 °C	1400 °C
Modulus of Elasticity	193 GPA	193 GPA
Electrical Resistivity	0.72 x 10^-6 Ω.m	0.74 x 10^-6 Ω.m
Thermal Conductivity	16.2 W/m.K	16.3 W/m.K
Thermal Expansion	17.2 x 10^-6/K	15.9 x 10^-6/K

304 vs 316 Stainless Steel: Heat Resistance

Stainless steel grade 304 has excellent resistance to oxidation in stop-go service up to 870°C and progressing service to 925°C. Yet, uninterrupted use at 425-860°C is not recommendable if the resistance of corrosion in water is needed. On this occasion, 304L is recommendable due to its resistance to carbide sedimentation.

Where extreme strength is necessary at above 500°C and up to 800°C temperatures, type 304H is recommended. This material will maintain aqueous corrosion resistance.

On the other hand, Stainless steel 316 has excellent resistance to oxidation in stop-go service to 870°C and ongoing service to 925°C. Yet, uninterrupted use at 425-860°C is not recommendable if the resistance of corrosion in water is essential. On this occasion, 316L is recommendable due to its resistance to carbide sedimentation.

Where extreme strength is needed at above 500°C temperatures, type 316H is recommendable.

304 vs 316 Stainless Steel: Fabrication

Fabrication of all stainless steels should be performed only with tools devoted to stainless steel substances. Tooling and work surfaces have to be cleaned entirely before use. This circumspection is essential to prevent cross-contamination of stainless steel by corroded metals. That may discolor the fabricated product’s surface.

304 vs 316 Stainless Steel: Cold Working

Stainless steel 304 efficiently work strengthens. Fabrication methods, including cold working, may demand a medium annealing stage to lessen work hardening and sidestep tearing or cracking. After fabrication, a complete annealing functioning should be employed to optimize corrosion resistance and reduce internal stresses.

As stainless steel 316 quickly brakes or roll, constituted into a diversity of parts. It is also appropriate to heading, stamping, and drawing, but post-work annealing is recommendable to ease internal stresses.

Cold working will increase both hardness and strength—stainless steel 316.

304 vs 316 Stainless Steel: Hot Working

Fabrication procedures, like forging, which include hot working, must occur after consistent heating to 1149-1260°C. The fabricated elements should then be fast cooled to assure maximum resistance of corrosion.

All usual hot working processes can be conducted on Stainless steel 316. Hot-working must be prevented under 927°C. The perfect temperature scope for hot working is 1149-1260°C. Post-work annealing is recommendable to assure maximum corrosion resistance.

304 vs 316 Stainless Steel: Heat Treatment

There is no way to harden 304 by heat treatment. Annealing or solution treatment can be done after heating to 1010-1120°C, by quick cooling.

The same as 304, stainless steel 316 also cannot be hardened by heat treatment. Annealing or solution treatment can be done after heating to 1010-1120°C, by quick cooling.

304 vs 316 Stainless Steel: Machinability

Stainless steel 304 and 316 have excellent machinability. Enhancing machining can be done by the use of the following rules:

Edges must be cut sharp. Dull edges cause surplus work hardening
Cuts have to be deep but light enough to avoid work hardening by getting the surface of the material rid on
Chip cutters should be used to help ensure swarf stays work-free
Low thermal conduction of austenitic alloys leads to heat focusing at the cutting edges. This means lubricants and coolants are essential and have to be used in large quantities

304 vs 316 Stainless Steel: Welding

Fusion welding performance for both Stainless steel 304 and 316 is excellent both with and with no fillers.

The recommended filler electrodes and rods for stainless steel 304 type 308 stainless steel. Heavy welded sections may need post-weld annealing.
Recommended filler electrodes and rods for Stainless steel 316 and 316L are the same as the foundation metal, 316, and 316L. Heavy welded segments may require post-weld annealing. In massive section welds, grade 316Ti can be used as a substitute to Stainless steel 316.

304 vs 316 Stainless Steel: Which is Popular

Most stainless steel handed down around the world is Grade 304. It offers the model corrosion resistance, strength, easy maintenance, and formability, for which stainless is known.

While 316 comes in second in the quantities sold, it provides highly superior resistant oh corrosion to acids and chlorides. This makes it widespread for a vast range of environments—including:

Medical implants and equipment
Foodservice, processing, and preparation atmospheres
Coastal environments
Areas with significant salt levels (such as roadways)
Brewing facilities
Environments with enhanced exposure to acids and alkalis

These higher resistances also help to permit you to sweep your stainless more frequently using stronger detergents and cleansers with slightly worry of harm or affecting the look of the stainless steel and have the guesswork out of cleaning.

This drives 316 to be an ideal upgrade for atmospheres with strict cleanliness and hygiene standards.

304 vs 316 Stainless Steel: Applications

With the benefits provided by 316 stainless steel, you might ask why 304 till the most popular.

If you’re hesitating which to choose, think about these common uses for the two grades:

304 Stainless Steel

Storage tanks
Indoor electrical enclosures
Wheel covers
Automotive trim
Kitchen equipment
Appliances
Decorative trim

316 Stainless Steel

Pharmaceutical equipment
Medical equipment
Chemical equipment
Stainless steel floats
Structural steel and components in marine environments
Commercial kitchen surfaces, equipment, and appliances

How to tell the difference between 304 and 316 stainless steel

You may need to check visually, find the differences between 304 and 316, and follow up to find the best ways to do correctly.

304 and 316 resistance to electricity differs – you can measure that. (if you have a consistent section of each to test)
304 corrodes a little when exhibited to seawater, but 316 does not.
304 looks a little duller than 316. depending on environmental exposure and surface finish, it is not the right way of telling, but you can go to the S.S. supplier and ask to see both models.
Once, the austenitic stability of SS316 is higher than of SS304. From many experiences in the distorted state, a strong magnet latches on SS304 but not on SS316.
Acid etching will be a virtue (and cheap) determinant, appreciating the gap in resistance to corrosion between the two types. But it only functions if the two metals are experienced with the same heat treatments.

F.A.Q

Here, you will find the most common questions, that may come to your mind, when thinking about the differences between 304 and 316 stainless steel. Follow up.

Summary: Stainless steel 304 vs. 316, which is better?

Stainless steel 304 vs. 316, which is better? Well, it depends on the application and needs.

The mechanical properties of both steel sheets are almost the same, and both have similar makeup material. Still, type 316 has more nickel than type 304 that helps 316 types resist more against chlorinated solutions such as seawater and de-icing salts.

For industrial use and commercial appliances, type 316 is better than 314 for its increased corrosion resistance. It has more resistance to chemicals and is considered superior to type 304 when it comes to exposure in salts and other chlorinated solutions. For marine applications, type 316 is ideal because type salt in the sea can damage the oxide layer of 304 types, leading to rust. That is the main reason why type 316 is a bit expensive as compared to type 304.

On the other hand, 304 types have a melting point higher than type 316 (50 to 100 °F higher than 316 types). 304 type is commonly used for residential appliances and indoor architectural hardware. Type 304 is better for the applications where chlorinated solutions are not a concern as it is less expensive than type 316.

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