Stainless steel is an alloy made up of different metals. When these metals are mixed in different quantities, they produce several variations of the alloy. Each variation has its own features and uses. There are over 150 varieties of stainless steel, and each of them has different properties, which are further split into grades.
For the food service industry, there are two types of stainless steel: SAE Grades and Flatware Grades. These two grades are commonly known as food-grade stainless steel.
Stainless steel is a fantastic metal, and that’s why it’s so widely used in the kitchen. It doesn’t break, bend or crack and stays shiny for years. Ever wondered why it’s so commonly used in the food service industry? Why not aluminium? Why not iron? Let’s find out.
Benefits of using stainless steel utensils:
- Corrosion-resistance: Stainless steel is a non-reactive metal alloy with 10-11% chromium. On being exposed to air, chromium forms a layer of chromium oxide over the surface. This layer prevents the steel from rusting by shielding it from moisture.
- Non-reactive surface: Unlike aluminium and iron, stainless steel is a non-reactive metal. It means you can cook acidic foods in stainless steel utensils without affecting the flavour of the food and without damaging the surface of the metal.
- Strength: Food grade stainless steel is strong and can be used in heavy-duty equipment or in shelving for storage areas.
- Ease of Cleaning: Cleanliness is an essential requirement of the food industry. Usually, wooden or plastic utensils have several openings where bacteria can grow if they are not cleaned properly. Compared to that, stainless steel has a smooth surface, and it doesn’t have any room for bacteria growth in the utensil.
Amongst lots of metals available in the market, stainless steel is considered as one of the best materials for kitchen utensils. It is incredibly useful due to its strength, durability, and corrosion resistance. It’s not just the food industry; stainless steel is useful in countless applications in different other industries as well.
In India, Aamor Inox is one of the leading manufacturers and suppliers of premium quality Stainless Steel products. We cater to diverse clientele around the world by manufacturing high-quality stainless steel products.
We serve different industries like dairy, instruments, pulp and paper, medical, etc. Based out of New Delhi, India, we export various stainless steel products to over 60 countries worldwide. Please share your enquiries with us on anand@aamorinox.com, and we’ll get back to you as soon as possible.
Often, people mistakenly believe that stainless steel is a single material. In reality, stainless steel refers to a family of corrosion-resistant steels. Therefore, it is very important for a consumer to understand the distinctive properties of various families and grades of stainless steel so that he can make an informed decision.
Even though stainless steel owes its corrosion resistance primarily to chromium, there are many combinations of metals available in the market today, which also fall within the category of ‘stainless steel’.
When you try to find the best option of stainless steel, you must determine the precise kind of alloy you require for your purpose. That will also help you identify the optimal price point according to your need.
The two major stainless steel labels are:
a) Families
b) Grades
Stainless Steel Families
The term ”stainless steel families” in this case refers to specific properties of that particular alloy. Different families have different ratios of various metals in the alloy. The four prominent stainless steel families include:
a) Austenitic
b) Ferritic
c) Duplex
d) Martensitic and Precipitation Hardening Stainless Steel
While families act as a differentiator at one level, you need to really look at grades of stainless steel to appreciate what separates one variety from another. Various grades refer to specific properties of the alloy such as toughness, magnetism, corrosion-resistance, and alloy composition.
Common stainless steel families and grades along with their characteristics:
Pairing a family and grade together gives you a good indication of what to expect from a particular stainless steel alloy. Be it magnetism, toughness, corrosion-resistance or heat-resistance, you can learn about everything by focusing on these two aspects.
The following classifications will make you aware of what to expect within each family as well as common grades.
Austenitic: This is the most widely used family of stainless steel worldwide. It mostly includes chromium and nickel, though some grades also include manganese and molybdenum. Austenitic stainless steel is non-magnetic when annealed with a solution. However, there are also certain cold worked grades that are magnetic. Heat-based hardening does not work for this type of stainless steel. However, it promises excellent corrosion-resistance and is also highly weldable. Austenitic stainless steel’s popular grades include 303, 304, 316, 310, and 321 grades.
Ferritic: This is one of the most cost-effective families of stainless steel available in the market. It has a low nickel content but includes chromium, molybdenum, niobium, and/or titanium. These metals improve the toughness and creep resistance of this alloy. This variety is magnetic, highly corrosion-resistant and weldable. Its most popular indoor applications include kitchenware, exhaust etc. This family is well-suited for applications where cost and performance matter more than visual appeal. Common grades of ferritic stainless steel include 409 and 430 grades.
Duplex: This family includes most of the recent and proprietary stainless steel alloys. If you opt for duplex grades, you can benefit the most from its properties, which are a combination of both austenitic and ferritic stainless steels’ properties. When it comes to the Duplex family of stainless steel, its characteristics depend upon the specific alloy. The characteristics include weight, toughness, and tensile strength. A number of alloys are created based on specific industrial concerns. This family of stainless steel is also available in a chloride-resistant variety, which is popular in offshore use. In this family, the common grades include 318L, LDX 2101, LDX 2304, 2507, and 4501.
Martensitic and Precipitation Hardening: Martensitic and precipitation hardening steels are the most common of the four major families of stainless steel. These are popular in applications that need a precise and hardened edge. This family is also the best choice for making knives, scissors, razors, and medical tools. This stainless steel alloy promises moderate to good corrosion-resistance and retains its magnetism after hardening. 410 and 420 grades are the common grades of martensitic and precipitation hardening steels. Be it making ornamental structures or rugged industrial applications, stainless steels have a wide range of usages and applications. It is crucial to understand the unique characteristics of different stainless steel alloys so that you make the right choice.
Steel as a broad term is loosely used to refer to an entire family of metal alloys. It is a common, highly versatile metal with a wide range of applications and uses. Steel comes in different grades but generally speaking, it can be divided into two categories: a) Carbon Steel b) Stainless Steel.
The basic attribute that differentiates the two is the chromium content. While carbon steel contains less than 10.5% of chromium, stainless steel must have at least 10.5% of chromium to be classified as the same. It is this characteristic that lends different properties to the two types of steel.
Difference between Stainless Steel and Carbon Steel:
Stainless Steel
This is mainly defined by the addition of chromium, along with certain other alloying elements such as nickel. It is also termed as ínox’ steel, as it is crafted to protect against oxidization, and hence, it is ínoxidizable’. Equipped with the protective layer of chromium which safeguards the metal’s iron content from being oxidized due to exposure to environmental oxygen, stainless steel is corrosion-resistant and thus called ‘stainless’.
Types of Stainless Steel
Depending on the chromium levels, stainless steel can further be divided into various categories. Usually, stainless steel with lower chromium content is cheaper and less durable. The following are the types of stainless steel with different properties:
Austenitic: This is the most widely used type of stainless steel, offering low yield strength but strong corrosion and heat resistance. It is commonly used in housewares, industrial piping and vessels, construction, and architectural facades.
Ferritic: This form of stainless steel usually does not contain nickel. However, this promises better corrosion, heat, and cracking resistance as compared to most other types. This form of stainless steel is frequently used in washing machines, boilers, and indoor architecture.
Martensitic: This is usually magnetic and due to its low chromium content, is not as corrosion-resistant as other types of stainless steels. It’s also very strong, and therefore, it’s used to make knives and turbine blades.
Duplex: This is a composite of austenitic and ferritic steels, and is thus, very strong and flexible. It boasts twice the yield strength of austenitic stainless steel and finds wide usage in industries such as paper, pulp, shipbuilding, and petrochemical industries.
Precipitation: This type of stainless steel has the same level of corrosion resistance as austenitic metals, but can be hardened to make it even stronger by adding other elements such as aluminum, copper, and niobium.
Advantages of Stainless Steel
– Corrosion-resistant
– High and low temperature-resistant
– Comes in different types
– Strong and highly durable
– Low-maintenance and can be easily cleaned
– Long-lasting
– Low-priced as compared to its lifespan
– Can be customized for an attractive cosmetic finish
– Does not tarnish easily
– Environment-friendly and recyclable
Applications:
Stainless Steel has a range of applications in many industries. The first industrial application of stainless steel took place way back in the 1930s by Ford, in the automotive industry. Ever since then, it has made its way into cars for exhaust systems, grills, trims, and different structural components. It is also used in aircraft construction, for making aeroplane frames, jet engines, and landing gear. Its corrosion-resistance and low-maintenance properties makes stainless steel highly useful for transporting and interacting with chemicals. Medical technology uses stainless steel too.
Thanks to its strength, resistance, and flexibility, certain types of stainless steels are used in architecture. The aesthetic features and attractive finish of stainless steel further enhance its desirability in architectural applications. It can also be cleaned easily. No wonder stainless steel’s price is considerably higher than carbon steel.
Besides, stainless steel is commonly used in the food and catering industry to manufacture cookware, cutlery, kitchen accessories, and appliances. It is interesting to note that the less ductile grades of stainless steel are used to make utensils such as knives, while the more ductile grades are used in the manufacture of grills, ovens, saucepans, and sinks.
Carbon Steel
As mentioned before, this type of steel has far lower chromium levels. Instead, it is formed from a carbon-like alloy with a few other materials. The carbon content in this is usually 2-2.5%. Though unlike stainless steel, carbon steel is susceptible to rust, the latter is cheaper and has different mechanical properties depending on its carbon content. Low-carbon steels are generally softer, and hence, can be machined and welded easily. On the other hand, high-carbon steel is stronger, but it is also much harder to process.
Types of Carbon Steel
It is the carbon content that constitutes the defining element of any carbon steel alloy. The various types of carbon steel can be categorized as follows:
Low-carbon steel: This is the most widely used form, with the carbon content being less than 0.25%. Since this is relatively weaker and softer but is more ductile and can be easily welded, this type of carbon steel is used for machining and welding at a low cost.
Medium-carbon steel: This variety usually has a carbon content of 0.25-0.6% and manganese content of 0.6-.1.65%. It can be improved via heat treatment. However, this can be performed only on very thin sections unless alloying elements are added. It is stronger but not as ductile as low-carbon steel.
High-carbon steel: This is the hardest and toughest type of carbon steel. It is the least ductile and is highly resistant to wear and tear. Its carbon content varies from 0.6% to 1.25% while the manganese content is about 0.3-0.9%.
