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Stainless Steel Grades – an Overview

Choosing the correct Stainless Steel is critical to any application, especially those designed for wash-down, corrosion resistance, heat resistance or strength. The main types of stainless steel alloys are austenitic, ferritic, martensitic, duplex and precipitation hardening stainless steels. The most widely used and popular is austenitic. Austenitic stainless steel is non-magnetic and its structure allows for the material to be hardened through cold-working.


Austentic stainless steel is a family of corrosion-resistant steel alloys that contain at least 10.5% chromium. Different grades of stainless steel have varying levels of other alloying elements, which contribute to their specific properties. There are a variety of materials to choose from with many different specifications. Grades 303, 304, and 316 are three common and widely used stainless steel alloys. Here's an overview of each:

303 Stainless Steel

Stainless steel grade 303 is a free-machining variant of the basic austenitic grade 304. It is known for its excellent machinability due to the addition of sulfur, which enhances the chip-breaking and machining capabilities of the material. However, its corrosion resistance is lower than some other stainless steel grades, and it may not be suitable for use in highly corrosive environments.


303 stainless steel, also known as EN 1.4305 grade, has specific properties that make it suitable for various applications. It’s often used for fasteners, bearings, bushings, nuts, bolts, screws, gears, and aircraft fittings. In environments with high corrosion potential, other stainless steel grades such as 304 or 316 may be more appropriate.


304 Stainless Steel

Stainless steel grade 304, also known as 18-8 stainless steel or 1.4301, is one of the most widely used and versatile stainless steels, characterised by its excellent corrosion resistance, formability, weldability, and durability. Stainless steel grade 304 is widely employed across various industries due to its versatility and cost-effectiveness. Its broad range of applications makes it a staple material in manufacturing and construction.


It is commonly used in applications such as kitchen appliances, food processing equipment, automotive trim, and architectural components. While 304 stainless steel is corrosion-resistant, it may not be suitable for extremely corrosive environments, such as those containing chlorides. In such cases, a higher alloyed stainless steel like 316 is preferred.


316 Stainless Steel

Stainless steel grade 316, often referred to as marine-grade stainless steel, is an austenitic stainless steel alloy known for its excellent corrosion resistance, particularly in harsh and corrosive environments. It is an upgraded version of 304 stainless steel with the addition of molybdenum, which enhances its resistance to pitting and crevice corrosion.


316 stainless steel is widely used in applications where corrosion resistance, strength, and formability are required, such as marine equipment, chemical processing, pharmaceuticals, medical implants, surgical instruments, and food and beverage production. If the environment has high amounts of corrosive elements and/or materials that would be placed underwater, 316 stainless is a preferred choice.


In conclusion, 303, 304 and 316 stainless steel are all popular materials in the field of metallurgy and engineering, and they have distinct differences that make them suitable for different applications. These differences primarily arise from variations in their composition and properties. Whether your application requires 303, 304 or 316 stainless steel, P&P Non-Ferrous carry a variety of configurable 300-grade stainless steel components including plates, tubing, fittings, pipes, fasteners, and rods/bars to fit your requirements.

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