Stainless Steel - Application, Types, Grades, Properties Full Overview

Stainless steel has countless applications in any industry. It is the most popular choice of materials used in metal fabrication for home appliances and other objects that must stay clean. Stainless steel can be formed into various shapes and sizes by processes such as casting, forging, rolling, and extrusion. It is also easy to clean and maintain, making it a popular material choice in many industries.

What is stainless steel?

Stainless steel is a type of steel alloy that is known for its high resistance to corrosion and staining, as well as its strength and durability. It is composed primarily of iron, with a minimum of 10.5% chromium content by mass, and may also contain other alloying elements such as nickel, molybdenum, and manganese.

The high chromium content in stainless steel creates a passive layer of chromium oxide on the surface of the metal, which prevents corrosion and oxidation. This makes stainless steel highly resistant to rust and staining, even in harsh environments.

Stainless steel is a versatile material that is used in a wide range of applications, including kitchen appliances, cutlery, medical equipment, construction materials, and in the production of chemical and pharmaceutical processing equipment. It is also commonly used in the automotive and aerospace industries.

Application of stainless steel

Stainless steel has a wide range of applications in various industries, including:

• Kitchen appliances: Stainless steel is a popular material choice for kitchen appliances such as refrigerators, ovens, and dishwashers, due to its corrosion resistance and aesthetic appeal.
• Cutlery: Stainless steel is commonly used to make cutlery, as it is durable, easy to clean, and does not corrode or stain.
• Medical equipment: Stainless steel is a popular material choice for medical equipment, such as surgical instruments, implants, and dental equipment, due to its hygienic properties and resistance to corrosion.
• Construction materials: Stainless steel is used in a variety of construction applications, including cladding, roofing, and structural support, due to its strength and durability.
• Chemical and pharmaceutical processing equipment: Stainless steel is often used in the production of chemical and pharmaceutical processing equipment, as it is highly resistant to corrosion and contamination.
• Automotive and aerospace industries: Stainless steel is used in various parts of automobiles and airplanes, due to its strength, durability, and resistance to corrosion.
• Consumer products: Stainless steel is used in a wide range of consumer products, such as watches, jewelry, and electronics, due to its aesthetic appeal and durability.
• Oil and gas industry: Stainless steel is used in the oil and gas industry for applications such as pipelines, offshore platforms, and processing equipment, due to its resistance to corrosion in harsh environments.
• Water treatment: Stainless steel is often used in water treatment plants for pipes, valves, and other equipment, due to its resistance to corrosion and ease of maintenance.
• Pulp and paper industry: Stainless steel is used in the pulp and paper industry for applications such as tanks, pipes, and bleaching equipment, due to its resistance to corrosion and strength.
• Renewable energy: Stainless steel is used in renewable energy applications such as wind turbines, solar panels, and hydropower plants, due to its strength and resistance to corrosion.
• Rail transportation: Stainless steel is used in the rail industry for applications such as train carriages, track components, and station architecture, due to its strength and resistance to corrosion.
• Architecture: Stainless steel is often used in architectural applications such as building facades, bridges, and sculptures, due to its aesthetic appeal and durability.
• Marine industry: Stainless steel is used in the marine industry for applications such as boat components, dock hardware, and seawater intake systems, due to its resistance to corrosion in saltwater environments.

Its versatility and durability make it a popular material choice in many different industries.

Benefits of Stainless Steel

Stainless steel has a number of benefits that make it a popular material choice for many applications, from consumer products to heavy industry applications. Some of the main benefits of stainless steel include:

• Corrosion resistance: Stainless steel is highly resistant to rust and corrosion, making it an ideal material choice for applications in harsh and corrosive environments.
• Strength and durability: Stainless steel is a strong and durable material that can withstand high temperatures and extreme conditions, making it ideal for use in applications that require high strength and durability.
• Aesthetic appeal: Stainless steel has a modern and sleek appearance that is often used in architecture, interior design, and consumer products.
• Hygienic: Stainless steel is easy to clean and has a non-porous surface that is resistant to bacteria and germs, making it a popular material choice for medical equipment, food processing, and pharmaceuticals.
• Recyclable: Stainless steel is 100% recyclable and can be reused to create new products, making it an environmentally friendly material choice.
• Versatility: Stainless steel can be formed into various shapes and sizes, making it a versatile material that can be used in a wide range of applications.
• Low maintenance: Stainless steel requires minimal maintenance, making it a cost-effective material choice in the long run.

Types of stailess steel

There are many different types of stainless steel, which are classified based on their microstructure, composition, and properties. Here are some of the most common types:

• Austenitic Stainless Steel: This is the most widely used type of stainless steel, which is non-magnetic and highly corrosion-resistant. It contains high levels of nickel and chromium, with some grades also containing molybdenum, titanium, and/or nitrogen. Examples include 304, 316, and 321.
• Ferritic Stainless Steel: This type of stainless steel is magnetic and has a lower corrosion resistance than austenitic stainless steel. It contains high levels of chromium, with some grades also containing small amounts of nickel or molybdenum. Examples include 409 and 430.
• Martensitic Stainless Steel: This type of stainless steel is magnetic and has a high strength and hardness. It contains high levels of chromium and carbon, with some grades also containing small amounts of nickel or molybdenum. Examples include 410 and 420.
• Duplex Stainless Steel: This type of stainless steel has a mixed microstructure of austenite and ferrite, with high levels of chromium, nickel, and molybdenum. It has a high strength and corrosion resistance, particularly in harsh environments. Examples include 2205 and 2507.
• Precipitation Hardening Stainless Steel: This type of stainless steel can be strengthened through a heat treatment process that causes precipitation of hardening phases. It has a high strength and corrosion resistance, particularly in aerospace and chemical processing applications. Examples include 17-4 PH and 15-5 PH.
• Austenitic-Ferritic (Duplex) Stainless Steel: This type of stainless steel is a combination of austenitic and ferritic stainless steels, providing a balance of strength and corrosion resistance. It contains high levels of chromium, nickel, and molybdenum, and is commonly used in applications such as chemical processing, oil and gas, and marine environments.
• Super Austenitic Stainless Steel: This type of stainless steel contains high levels of chromium, nickel, and molybdenum, as well as nitrogen and copper. It has excellent corrosion resistance in acidic and chloride environments, and is used in applications such as chemical processing, pulp and paper, and desalination.
• High-Performance Stainless Steel: These are specialized stainless steels designed for specific applications that require high strength, corrosion resistance, or other specialized properties. Examples include high-temperature alloys such as Inconel and Hastelloy, as well as medical-grade stainless steels such as BioDur 316LS.
• Free-Machining Stainless Steel: This type of stainless steel is designed to be easily machinable, making it ideal for applications such as automotive and aerospace components. It contains additional elements such as sulfur, selenium, or lead, which improve machinability but may reduce corrosion resistance.
• Low-Nickel Stainless Steel: This type of stainless steel is designed to have a lower nickel content than traditional austenitic stainless steels, reducing the cost and increasing the availability of the material. It contains additional elements such as nitrogen or manganese to maintain strength and corrosion resistance.

Each types of stainless steel has its unique properties and characteristics. The choice of stainless steel for a particular application depends on the requirements of that application, including factors such as corrosion resistance, strength, and cost.

Grads of Stainless Steel

The material grade of a stainless steel refers to the specific composition and microstructure of the steel. Each grade is designated with a numerical code and letter combination, such as 304 or 316, which provide information about the elements that make up the steel and its properties.

Different material grades of stainless steel are often used for different applications, depending on the specific requirements of the application. For example, austenitic grades like 304 and 316 are commonly used for food processing equipment and medical devices, while ferritic grades like 430 are often used for automotive trim and decorative applications.

Stainless steel grades that are classified based on their composition and properties. Here is an overview of each series of stainless steel grades:

• 300 Series: The 300 series of stainless steel is the most common and widely used group of stainless steels. It includes austenitic grades such as 304, 316, and 321, which are highly corrosion-resistant, non-magnetic, and have good ductility and toughness. They are often used in applications such as food processing, chemical processing, and medical equipment.
• 200 Series: The 200 series of stainless steel includes austenitic grades such as 201 and 202, which are less expensive and less corrosion-resistant than the 300 series. They are often used in applications such as appliances, kitchen utensils, and automotive trim.
• 400 Series: The 400 series of stainless steel includes ferritic and martensitic grades such as 409, 410, 430, and 440, which have lower corrosion resistance and higher hardness than the 300 series. They are often used in applications such as automotive exhaust systems, cutlery, and valve components.

Properties of stainless steel

Mechanical property

• Tensile strength: This is the maximum amount of stress that a material can withstand before it breaks. Tensile strength is an important measure of a material's ability to resist deformation and failure under tension. Stainless steel has a high tensile strength, making it a strong and durable material.
• Yield strength: This is the amount of stress that a material can withstand before it begins to deform permanently. Yield strength is an important measure of a material's ability to withstand loading and deformation. Stainless steel has a relatively high yield strength compared to other metals.
• Ductility: This is a measure of a material's ability to deform without breaking. Stainless steel has good ductility, which means it can be formed into various shapes and sizes without cracking or breaking.
• Hardness: This is a measure of a material's resistance to scratching and indentation. Stainless steel has a relatively high hardness, making it resistant to wear and tear.
• Toughness: This is a measure of a material's ability to absorb energy before breaking. Stainless steel has good toughness, which means it can withstand impacts and shocks without breaking.

Chemical property

• Corrosion resistance: The presence of chromium in stainless steel creates a passive oxide layer on the surface, which helps to protect it from corrosion. The level of corrosion resistance depends on the amount of chromium, as well as other elements like molybdenum and nickel, in the alloy.
• Chemical inertness: Stainless steel is relatively inert, meaning that it does not react readily with most chemicals. This makes it a useful material for applications where it will be exposed to a range of chemicals, such as in the chemical processing and pharmaceutical industries.
• Resistance to oxidation: Stainless steel resists oxidation, or the reaction of a material with oxygen, which can cause rust or other forms of corrosion. The high levels of chromium and other alloying elements in stainless steel help to prevent oxidation and maintain the integrity of the material.
• Biocompatibility: Some grades of stainless steel are biocompatible, meaning that they do not harm living tissue or cause adverse reactions when used in medical implants or devices.

More properties

• Heat resistance: Stainless steel has good heat resistance, making it suitable for use in high-temperature applications. Austenitic stainless steels, in particular, are known for their high-temperature strength and resistance to scaling and oxidation.
• Hygiene and cleanability: Stainless steel is easy to clean and sanitize, making it a popular choice for food processing and medical applications. Its smooth, non-porous surface resists contamination and does not harbor bacteria or other harmful microorganisms.
• Aesthetics: Stainless steel has a bright, clean appearance that makes it an attractive material for architectural and decorative applications. It is also available in a wide range of finishes and textures, allowing for customized looks.

These material properties, along with others, make stainless steel a popular and versatile material in a range of industries and applications.

Summary

Stainless steel is a wonder material and has a highly positive impact on the industry as a whole. Due to so many grades with different properties, there is always a grade that is perfect for an application. It is essential to choose the grade wisely to ensure a cost-effective investment.