What is Stainless Steel & What is it Used For
Stainless steel is a strong, corrosion-resistant alloy essential in industries ranging from construction and automotive to oil and gas and medical equipment. Its flexibility and strength allows it to be an indispensable material to be used in harsh and normal environments.
In this guide, we'll explore the types, properties, grades of stainless steel, and most importantly we will discuss the stainless steel uses.
What is Stainless Steel?
Stainless steel is a type of iron-based alloy containing at least 10.5% chromium, which forms a protective layer on its surface, preventing rust and corrosion. It is suitable in various environments and it is also improved by other elements, which include nickel, molybdenum, carbon, and nitrogen. With its superior mechanical properties and resistance to extreme temperatures, stainless steel is often chosen for both structural and decorative applications.
Stainless Steel Properties
Corrosion-resistant
Stainless steel is known for its corrosion-resistant properties; it's what separates it from regular steel. The alloy also has chromium, which provides the steel with its oxide layer making it have the corrosion-resistant property. The oxide layer can repair itself and in case the surface is dismantled, the surface will be still resistant to corrosion. Conversely, the carbon steels are safeguarded through the use of coating such as galvanising. It is unfortunate that damage on the surface will lead to the exposure of the steel and expose it to corrosion making it develop problems in its full lifetime value.
Various grades of steel have different resistance and chloride increases the speed of corrosion in certain grades. The most resistant to corrosion are the grades containing nickel, chromium and molybdenum.
Magnetism
The attraction of steel to a magnet is referred to as magnetism. Austenitic grades are typically non-magnetic though cold working can be made magnetic. High nickel grades will also be non-magnetic and ferritic steels are magnetic.
Tensile Strength
When compared with mild steel, stainless steel has more tensile strength, and duplex stainless steel has better tensile strength than austenitic stainless steel. The most tensile steel is however observed in martensitic steel and may possess higher strengths than the aforementioned steel.
Cryogenic Resistance
At sub-zero temperatures, the toughness and ductility of austenitic stainless steel are increased, whereas ferritic and martensitic stainless steel should not be used at these temperatures.
Types of Stainless Steel
Stainless steel comes in four main types: austenitic, ferritic, martensitic, and duplex. Depending on its composition and microstructure, each of the types has peculiar properties and is applied to various purposes.
Austenitic Stainless Steel
It is the most common type which has good corrosion resistance, ductility and weldability. General applications include food processing equipment, medical equipment and chemical plants. It is a high-performance type. Pitting in the severe environment is resisted by the increased nickel content.
Ferritic Stainless Steel
Low-cost and magnetic, and has good corrosion resistance to use in the indoors or general purposes. Its applications include kitchen appliances, car exhausts, and sinks. It has little or no nickel which makes it cheaper compared to austenitic grades.
Martensitic Stainless Steel
It is powerful and durable and so it is suitable in high tension designs. It fifnds application in surgical equipment, knives and forks, and aircraft parts. It is both harder and tougher than austenitic and ferritic grades but not as corrosion resistant as them.
Duplex Stainless Steel
It possesses austenitic plus ferritic properties (50/50), which are of high strength and better corrosion resistance. Typical applications include pipelines, pressure vessels and marine structures that use oil and gas. It is suitable for heavy duty applications, in environments where stress corrosion cracking and chloride are likely to occur.
Stainless Steel Grades
The grading of steel can be done in many different ways depending on the country that we are dealing with, we shall use the SAE steel grading series as that is the one that we base our steel on and it is used globally.
- Series 100 Steel
- Series 200 Steel - chromium-nickel-manganese alloys of austenitic type.
- Series 300 Steel - austenitic chromium-nickel alloys.
- Series 400 Steel - chromium ferritic and martensitic.
- Series 500 Steel - chromium heat-resistant alloys.
- Series 600 Steel - designed on proprietary alloys (no longer graded by the SAE).
- Series 900 Steel - austenitic alloys of chromium-molybdenum.
Stainless Steel Applications
Steel can be used in any industry, however, there are industries that are more interested in the product, including those industries that require machinery or production parts. Stainless steel uses are evident in many industries, such as medical equipment, food processing, pulp and paper, power plants, civil engineering, bridge building and shipbuilding. The stainless steel applications are discussed as follows:
- Automobile use - catalytic converters, exhausts, and structural applications. Steel contributes to lowering the long term maintenance expenses, lifetime value and environmental impact.
- Trade construction industry - cladding, facades, and roofing. Stainless steel is known for its anti-vandalism properties and is popular for public equipment like ticket machines.
- Mining & materials - stainless steel has played a part in many large-scale projects, with improved tools and better facilities for workers to live in.
- Railway industry - stainless steel is corrosion-resistant and offers excellent mechanical properties, which is ideal for the railway industry. Austenitic stainless steel has been used for carriages, and ferritic stainless steel is used for freight wagons.
- Oil and gas industry - stainless tanks, pipes, pumps and valves. The steel industry is also dependent on oil and gas industry as it is corrosion resistant.
Get Stainless Steel Products from Trusted Supplier
Stainless steel is an indispensable material, offering a unique combination of strength, durability, and exceptional corrosion resistance due to its protective chromium layer. With its flexibility in the types and grades of austenitic grades available in medical equipment to the immense strength of duplex steel in the strenuous oil and gas industry, its numerous types and grades ensure that it is applicable in virtually any industry. Its value in the long run, its low maintenance, and its ability to fit in harsh and normal environments solidify its position in the engineering and construction industry of the present.
For your stainless steel needs, including standard and high-performance Austenitic and Duplex grades stainless steel products, contact Amardeep Steel Center. The experience we have and the number of products we offer make us your reliable supplier of quality pipes, tubes, plates, and fittings. Get a quote on a project today!