What is Stainless Steel?
Stainless steel is an iron-containing metal that is used in a wide range of applications. Because of its chromium content, it has outstanding stain or rust tolerance, typically from 12 to 20 percent of the alloy. In addition to many patented alloys developed by different stainless steel manufacturers, there are more than 57 stainless steel grades which are known as common alloys. Metallurgists looked into the possibility of iron-chromium alloys over many decades in the 1800s, and the Stainless Steel seemed to offer much greater durability and corrosion resistance than traditional carbon steel.
Stainless steel has a broad range of uses on both the manufacturing and consumer markets thanks to its superior corrosion resistance, high strength, and desirable look. The food processing industry in India consumes about 200,000 tons of nickel-containing stainless steel every year in their day to day applications. The Stainless Steel is immensely used in the Architectural industry. Stainless steel first gained prominence during the era of art-deco architecture. Famously, Chrysler Building’s upper portion was constructed of stainless steel. Industries like chemical, processing and oil & gas industries are some of the most demanding industries for Stainless steel. They use Stainless Steel to manufacture various valves, pumps, tanks and pipes.
Classes of Stainless Steel
The Stainless Steel Family consists of five different recognized classes. The Five Classes of Stainless Steel are named as Austenitic stainless steel, Ferritic stainless steels, Martensitic stainless steel, Precipitation-hardening stainless steel, and Duplex stainless steel. The most common of them is austenitic stainless steel. The austenitic class includes the 200 and 300 series of grades. There is a lot of similarity between the Ferritic and Martensitic Stainless and they both consist alloys in the 400 series of Stainless Steel
The Grades of Stainless Steel are classified based on the proportion of each element they contain. The percentage of the Iron, chromium, nickel, molybdenum, and carbon help to decide the grade of the Stainless Steel. There are more elements added to the Stainless Steel to achieve various properties like Increased corrosion resistance, Low-temperature resistance, High-temperature resistance, Improved weldability, Improved strength, etc.
How is Stainless steel made?
The process of manufacturing of Stainless Steel ends with a different process for each different grade. But id the basics aren’t right, the metal is of no use. Before coming to a deliverable product, the process starts with the creation of the molten alloy.
Step 1: Selection of raw materials.
The very first step starts with selecting of the right elements to put in the Stainless Steel. The elements to be added are decided by the different properties that are to be achieved with the final product. For example, the higher the chromium content is the more corrosion resistivity of the final product is achieved.
Step 2: Melting of Raw Materials
The process continues with the Melting of all the Scarp Materials. All the additives and Raw materials are melted in an electric arc furnace and a fluid mixture is created after a course of heating the materials for several hours. This process is also used to recycle Stainless Steel. Because of their Melting point, Stainless steel is 100% Recyclable.
The temperatures of the Melting them is varied for various grades and classes of stainless steel.
Step 3: Removal of the Excess Carbon
Carbon is added to the iron-based Stainless Steel for more toughness and strength. When the carbon is added to the Stainless Steel in excess, it can cause certain problems like carbide precipitation during welding.
The Carbon content can be removed with two different processes. The First process is called as Argon oxygen decarburization (AOD) and Vacuum oxygen decarburization (VOD). These processes are also used for the creation of the low carbon variants of the different stainless steel grades such as SS 304L.
Step 4: Tuning
The process of Tuning is carried out to do fine adjustments in the chemical composition of the Stainless Steel. Tuning means steel is slowly stirred within the temperature limits. Tuning helps in removing all the unnecessary elements and unwanted particles from the composition. This also helps in improving the consistency of Stainless steel.
Step 5: Forming
After the process of tuning, the metal is ready for Forming. Forming means casting of the metal in the desired shape and sizes. The Liquid fluid is now poured in the cast and various shapes like Blooms, Rods, Slabs, and Tubes are created.
Step 6: Hot rolling and Cold Rolling
The process of Hot rolling is carried out at a temperature above the recrystallization temperature of the steel and Cold rolling is carried out in temperatures below the recrystallization temperature of steel. In Hot rolling, the steel forms are passed through heated rolls. The Blooms are converted to bar and wire. Slabs are converted into sheets and Plates.
Step 7: Cutting and Finishing.
The Final Step in the manufacturing of stainless steel is Cutting and Finishing. The Stainless steel is cut into desired shapes and sizes. They are cut using the guillotine knives and circular knives or they are sawed using high-speed blades. After achieving the final product, various finishes are added to Stainless steel. These finishes are achieved by grinding or polishing the Stainless steel surface by Grinding wheels or abrasive belts.
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