So many products we use in and around our homes are made from stainless steel. From bowls, to water bottles, to cutlery, to appliances, stainless steel takes up a lot of real estate.

But how much do we actually know about stainless steel?

My guess is, that since you are reading this article, not as much as you would like. You want to know more about food grade stainless steel. You want to be informed about the materials used in your home.

In this article, I explain the differences between various types of stainless steels.

As well, I scoured the internet and answered questions that are commonly asked about food grade stainless steel.

So grab a coffee, sit back, and get prepared to know everything you will ever need about food grade stainless steel.

What is stainless steel?

The key element that classifies steel as stainless is that the iron alloy (mix of several metals) is comprised from a minimum of 10.5% chromium.

The main requirement for stainless steels is that they should be corrosion resistant for a specified application or environment.

Alloying elements are added to enhance their structure and properties such as formability, strength, and toughness.

These may include:

  • Chromium
    • increases resistance to oxidation
    • the higher the percentage, the higher increase in corrosion resistance
  • Nickel
    • the essential element in the 300 series of stainless steel
    • provides strength and toughness
    • makes material non-magnetic
  • Molybdenum
    • adds resistance to pitting of stainless steel due to chlorides
  • Titanium
    • used to stabilize stainless steel in the manufacturing process
  • Copper
    • added to austenitic stainless steel containing molybdenum
    • improves corrosion resistance to sulfuric acid
  • Carbon
    • always present in stainless steel
    • levels are low in all types of stainless steel except martensitic
    • higher levels in martensitic provide strength and hardness
  • Nitrogen
    • increases resistance to pitting
  • Silicon
    • added to stainless steels containing molybdenum
    • improves corrosion resistance to sulfuric acid
    • improves resistance to oxidation
  • Manganese
    • replaces some of the nickel in the 200 series stainless steels
    • assists in de-oxidation during the manufacturing process

The selection of a particular “type” and “grade” of stainless steel must meet the corrosion resistance requirements.

There are three types of stainless steel:

  • austenitic
  • ferritic
  • martensitic

What is food grade stainless steel?

While there is no official classification of ‘food grade’ stainless steel, the 316 grades are commonly referred to as food grade stainless steel.

There are other grades of stainless steel that are also suitable for food processing and handling such as the 200 series, 304 and 430 types.

Stainless steel grades 200’s, 304 and 316 are considered austenitic stainless steels whereas 430 grade is considered a ferritic stainless steel.

What are Austenitic stainless steels?

Austenitic are the most common types of stainless steels.

Austenitic steels are non-magnetic stainless steels that contain high levels of chromium, nickel and low levels of carbon.

They are known for their formability and resistance to corrosion.

Nickel-based austenitic steels are classified as 300 series. The most common grade is 304, which consists of 18% chromium and 8% nickel. Also known as 18/8 stainless steel.

Eight percent is the minimum amount of nickel that can be added to a stainless steel containing 18% chromium in order to completely convert all the iron alloy to austenite.

Molybdenum can also be added to a level of about 2% for grade 316 to improve corrosion resistance.

Austenitic steels are non-magnetic in the annealed condition, although they can become slightly magnetic when cold worked (the process of strengthening a metal by changing its shape without the use of heat). They have good formability and weldability, as well as excellent toughness, particularly at low or cryogenic temperatures.

Austenitic grades also have a low yield stress and relatively high tensile strength.

While austenitic steels are more expensive than ferritic stainless steels, they are generally more durable and corrosion resistant.

food grade stainless steel 200 grade

These grades of stainless steel have low nickel content. They are referred to as chrome-manganese stainless steels.

Properties

  • corrosion resistant, although less resistant to pitting than 300 series
  • tough – harder and stronger than 300 series
  • cheaper because of low nickel content

Applications

  • dishwashers
  • cutlery
  • cookware
  • food and beverage equipment

Stainless steel grade 304

304 stainless steel is the most common form of stainless steel used around the world, largely due to its excellent corrosion resistance and value.

Properties

It contains between 16 and 24% chromium and up to 35% nickel, as well as small amounts of carbon, silicon, and manganese. The remainder of the chemical composition is primarily iron.

Because of the high percentage of chromium contained in 304 grade stainless steel, 304 can withstand corrosion from most oxidizing acids.

That durability makes 304 easy to sanitize, and therefore ideal for kitchen and food applications.

304 stainless steel does have one weakness: it is susceptible to corrosion from chloride solutions, or from saline environments like coastal regions.

Chloride ions can create localized areas of corrosion, called “pitting,” which can spread beneath protective chromium barriers to compromise internal structures.

The high amounts of chromium and nickel give 304 stainless steel excellent corrosion resistance (except against chloride).

Applications

Common applications of 304 stainless steel include:

  • Appliances such as refrigerators and dishwashers
  • Commercial food processing equipment
  • Fasteners
  • Piping
  • Heat exchangers
  • Structures in environments that would corrode standard carbon steel

Stainless Steel Grade 316

Grade 316 is the most common grade of stainless steel. It is also known as 18/10 stainless steel.

Properties

Grade 316 stainless steel is an austenitic chromium-nickel stainless steel that contains between 2-3% molybdenum.

The molybdenum content:

  • increases corrosion resistance
  • improves resistance to pitting in chloride ion solutions
  • increases strength at high temperatures

Applications

Grade 316 stainless steel is used when increased corrosion resistance is needed, such as:

  • food processing
  • commercial kitchens
  • chemical processing
  • water treatment
  • swimming pool fittings
  • laboratory equipment

Stainless Steel Grade 304 VS 316

Grades 304 and 316 sound pretty similar, but there are some notable differences between the two.

Grade 304

  • 18% chromium
  • 8% nickel
  • 0% molybdenum
  • NOT chlorine resistant
  • corrosion resistant

Grade 316

  • 18% chromium
  • 10% nickel
  • 2% molybdenum
  • IS chlorine resistant
  • superior corrosion resistance
You may be wondering why grade 316 is not as popular as grade 304 stainless steel since it resists corrosion better and is chlorine resistant.

Well, it comes down to two factors: 

  • cost
  • corrosion resistance requirements

If you don’t need the added resistance of 316, standard 304 grades will provide similar performance and longevity at a lower price point.

As a consumer purchasing a product, chances are you will not know what grade of stainless steel you are purchasing. Products are generally unmarked. You have to trust that the manufacturer picked the most appropriate grade stainless steel for the intended use of their product.

What are ferritic stainless steels?

Ferritic stainless steels contain a high chromium content with low carbon content and in most cases very little nickel content.

The main alloying element is chromium, with contents typically between 11 and 17%.

Carbon is kept low which results in these steels having limited strength.

They are magnetic.

Stainless steel grade 430

Grade 430 is the most common ferritic stainless steel grade in sheet form.

Properties

  • composed of approximately 17% chromium
  • O.K. corrosion resistance
  • nickel is not present
  • magnetic

Grade 430 stainless steel does well indoors.

Mild detergents and cleaners can be used on this grade.

Applications

  • cutlery
  • kitchen utensils
  • catering equipment
  • microwave oven liners
  • induction heated pots and pans
  • cooker hobs
Summary of food grade stainless steels:
200 Series

  • 17% chromium
  • 1-6% nickel
  • 0% molybdenum
  • 5-15% manganese
  • 0.25-0.4% nitrogen
  • NOT chlorine resistant
  • least corrosion resistance

Grade 304

  • 18% chromium
  • 8% nickel
  • 0% molybdenum
  • NOT chlorine resistant
  • better corrosion resistance

Grade 316

  • 16% chromium
  • 10% nickel
  • 2% molybdenum
  • IS chlorine resistant
  • superior corrosion resistance

Grade 430

  • 17% chromium
  • 0% nickel
  • 0% molybdenum
  • Fair corrosion resistance

Martensitic Stainless Steel

Although this is not considered a type of food grade stainless steel, there are some applications of this type of stainless steel that can be found in the kitchen.

Properties

Carbon is the key element in martensitic steels. The higher the carbon concentration is, the ‘harder’ the stainless steel will be.

Carbon levels can vary from less than 0.1% to over 1%.

The corrosion resistance of martensitic stainless steels is generally lower than
the other types of stainless steel.

Applications

The combination of high strength, good toughness, and moderate corrosion
resistance allow martensitic stainless steel to be used in a wide variety of applications
including:

  • blades and cutting tools
  • surgical instruments
  • razor strips
  • cutlery

Summary of the different types of stainless steel

Austenitic

  • 18% chromium
  • 8% nickel
  • most commonly used stainless steels
  • non-magnetic

Ferritic

  • 10.5-18% chromium content
  • magnetic

Martensitic

  • 12-18% chromium
  • high carbon content
  • 0.1-1.2% carbon
  • magnetic

Q&A TIme!

All of your food grade stainless steel questions answered!

Is Food Grade stainless steel magnetic?

Ferritic and martensitic grades of stainless steel are magnetic. Austenitic grades are not magnetic due to their nickel content.

Does Food Grade stainless steel rust?

Stainless steels are corrosive resistant due to their chromium content. However, with the addition of other elements, they do have a range of corrosion resistance.

In order from most rust resistant to least rust resistant, here is a list of food grade stainless steels:

  1. Austenitic (grade 316 is more corrosion resistant than grade 304)
  2. Ferritic
  3. Martensitic

What is food grade stainless steel made from?

Food grade stainless steel is made from different metal alloys and elements depending on the properties desired for the stainless steel, such as:

  • nickel
  • molybdenum
  • titanium
  • manganese
  • copper
  • carbon
  • nitrogen

Does Food grade stainless steel contain nickel?

Austenitic stainless steels contain nickel. Most other types do not.

Is 304 Food Grade stainless steel?

Yes, it is an austenitic stainless steel and is considered food grade.

What types of food grade stainless steel are:

  • Bowls: Austenitic – Grade 304
  • Canteens: Austenitic – Grade 304
  • Containers: Austenitic – Grades 304 or 316
  • Cookware: Austenitic – Grades 304 or 316
  • Countertops: Austenitic – Grades 304 or 316
  • Cups: Austenitic – Grade 304
  • Dinner Plates: Austenitic – Grade 202 or 304
  • Dog Bowls: Austenitic – Grade 304
  • Electric kettles: Austenitic – Grade 304
  • Frying pans: Austenitic – Grades 304 or 316
  • Knives: Martensitic or Ferritic – Grade 430
  • Lunchboxes: Austenitic – Grades 200s, 304 or 316
  • Pots and Pans: Austenitic – Grades 304 or 316
  • Skillets: Austenitic – Grades 304 or 316
  • Straws: Austenitic – Grade 304
  • Travel Mugs: Austenitic – Grade 304
  • Utensils: Austenitic – Grades 304 or 316, Ferritic – Grade 430, or Martensitic
  • Water Bottles: Austenitic – Grade 304

What is the best food grade stainless steel?

That depends on what the stainless steel will be used for. There is no cut-and-dry answer to this question.

For example, if you’re looking for a high-quality knife, martensitic would be tougher than an austenitic grade. However, if you’re looking for a water bottle, austenitic grades would better since they are more resistant to corrosion.

How Do you Clean Food grade stainless steel?

For general household use, wash with a mild detergent (such as dish soap) and use a soft, non-scouring cloth to help keep the surface scratch-free.

For industrial use, a specific stainless steel cleaner may be more appropriate.

Where do you buy food grade stainless steel cleaner?

Stainless steel cleaner can be purchased from most department stores such as The Home Depot, and Walmart. It can also be found on Amazon here.

What are food grade coatings for stainless steel?

In this instance, the term food grade refers to a finish that is safe for processing food products and can easily and reliably be cleaned and sanitized.

Fluoropolymers are the most widely used stainless steel coatings.

There are two main types:

  1. PTFE (polytetrafluoroethylene): also known as Teflon
  2. FEP (fluorinated ethylene propylene)

Benefits of Stainless Steel coatings:

  • Resistance to hot water, oils, fats, and steam
  • Withstands extreme hot and cold temperatures
  • Non-stick container coating
  • Makes for easier and faster cleaning
  • Food prep equipment protection
  • Quick mold release

What is food grade sealant for stainless steel?

Generally, sealant is used to seal stainless steel joints. It’s main function is to keep moisture out of unwanted places. Sealant is typically used on food processing equipment, appliances, and sinks.

Food grade sealants resist the growth of fungus, mold and mildew. They are also resistant to chemicals such as acids, alkalis and many solvents, as well as boiling water, fats, and oils.

Most food grade sealants are made from silicone.

How do you identify food grade stainless steel?

It is almost impossible for the average consumer to identify different types of stainless steel.  Stainless steel manufacturers generally use chemical testing to differentiate between types of stainless steel. That’s not ideal for the typical consumer.

The one type of testing suitable for consumer use differentiates between austenitic and ferritic or martensitic types of stainless steel. It is not too specific, but will at least give you a general idea of the type of stainless steel in question.

That is the magnet test. Austenitic grades (200’s, 304 and 316) will NOT be magnetic, whereas ferritic and martensitic types will be magnetic.

Is stainless steel the safest cookware?

No.

While it is generally safe to use, it is not THE safest cookware available.

Stainless steel is an alloy (made from a combinations of different metals), so there is a potential of some metals, specifically nickel (which our body does not need or use) leaching into foods prepared with stainless steel cookware.

Leaching can happen with lower quality stainless steel cookware as well as higher quality stainless steel that contain a large amount of nickel. Although the amount of leaching is minimal, it’s something to be aware of, especially if you are allergic to nickel.

There are types of stainless steel cookware  made from grade 430 (ferritic) stainless steel that do not contain nickel. These may be a good alternative for some consumers.

Is stainless steel toxic when heated?

No. It is true that leaching of nickel and chromium does occur when stainless steel is heated, however, they do not reach toxic levels. That being said, consumers with nickel or chromium allergies may have a reaction and should probably not use stainless steel cookware just in case.

What is the best stainless steel for food contact?

Although there is no specific answer to this question regarding all of the types of food grade stainles steel, there are properties that make some stainless steels more appropriate to use than others depending on the desired function of the stainless steel.

This study from Food Protection Trends is very thorough and informative. Here is an excerpt of there concluding remarks:

It is clear from the foregoing discussion
that not all stainless steels are
created equal. Fabricators/manufacturers
of food processing equipment must
consider food types, cleaning/sanitizing/
sterilization processes, and all environments
of intended use when selecting
stainless steel material types. Food processors
must be aware of the general
properties and of the diversity of stainless
steels. If the wrong type of stainless steel
is selected for severe use applications, it
will surely fail and cause processed food
products to be unacceptable for market
or human consumption.

Is Food grade stainless steel safe?

Yes. Although leaching of some elements of stainless steel (particularly nickel and chromium) can occur, they generally are not toxic or present in amounts that are unsafe for the average consumer.

Did I miss anything? Would you like a more detailed answer on a specific question? Let me know in the comments below, I’d love to hear from you!

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