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Composition and Properties of Stainless Steel

The composition of stainless steel

Stainless steel is one of the most versatile and widely used materials in the world. It is strong, durable, and corrosion-resistant, making it ideal for a variety of applications. But what exactly makes up stainless steel? Let’s take a look at the composition of this incredibly useful material.

What is Stainless Steel ?

Stainless steel is an iron-based alloy that contains a minimum of 10.5% chromium, making it highly resistant to corrosion and rusting. It also has excellent durability, strength, and aesthetic appeal which makes it the ideal choice for numerous applications ranging from architecture to kitchenware.

Stainless Steel Properties

Stainless steel is a remarkable material renowned for its unique and invaluable properties. Its high resistance to corrosion, strength and durability make it an incredibly reliable and robust material, ideal for use in a range of industries. This material is incredibly versatile, enabling it to be used in diverse applications such as cutlery, surgical instruments, industrial equipment, and even in architecture. It is non-porous, which makes it resistant to bacterial contamination and easy to clean. Additionally, stainless steel has a remarkable sparkly appearance when polished, which makes it an aesthetically pleasing material to work with. There is no question that stainless steel continues to be one of the most popular materials for manufacturing due to its remarkable properties and incredible versatility.

Stainless Steel Composition

Stainless steel is widely known for its durability and strength. What makes it so dependable is its composition, which consists of carbon, manganese, nickel, silicon, phosphorus, and chromium. Together these elements create a metal that offers protection against corrosion and rust while offering high resistance to heat and temperature fluctuations. As a result, stainless steel can be found in a multitude of applications across many different industries including construction, medical equipment production, food and beverage preparation and storage, automotive engineering, and chemical manufacturing. Its ability to withstand such diverse environments makes it uniquely reliable amid changing circumstances.

Other common additives include:

  • Nickel
  • Carbon
  • Manganese
  • Molybdenum
  • Nitrogen
  • Sulfur
  • Copper
  • Silicon
Type Cr Ni Cmax Other Elements Major Characteristics
303 17.00-19.00 8.00-10.00 0.15 S 0.15 min † Free-machining modification of Type 302
303 Se 17.00-19.00 8.00-10.00 0.15 Se 0.15 min † Free-machining version of Type 302. Produces better surface finish than Type 303.
304 18.00-20.00 8.00-10.00 0.08 † Low carbon variation of Type 302. Minimizes carbide precipitation during welding
304L 18.00-20.00 8.00-10.00 0.03 † Extra-low carbon content eliminates harmful carbide precipitation due to welding
309 22.00-24.00 12.00-15.00 0.20 † High strength and resistance to scaling at high temperatures
310 24.00-26.00 19.00-22.00 0.20 † Higher alloy content improves basic characteristics of Type 309
316 16.00-18.00 10.00-14.00 0.08 Mo 2.00-3.00 † Mo improves general corrosion and pitting resistance and high temperature strength over that of Type 302
316L 16.00-18.00 10.00-14.00 0.20 Mo 2.00-3.00 † Extra-low carbon version of Type 316. Eliminates harmful carbide precipitation due to welding
317 18.00-20.00 11.00-15.00 0.08 Mo 3.00-4.00 † Higher alloy content improves basic advantages of Type 316
321 17.00-19.00 9.00-12.00 0.08 Ti 5 x C. min † Stabilized to permit use in 800-1500°F temperature range without harmful carbide precipitation
347 17.00-19.00 9.00-13.00 .008 Cb + Ta 10 x C. min † Characteristics similar to Type 321. Stabilized by Cb and Ta.
348 17.00-19.00 9.00-13.00 0.08 Ta 0.10 max Cb 0.20 max
Cb + Ta 10 x C min
† Similar to Type 347 but Ta reduced for atomic energy applications
410 11.50-13.50 0.15 ¥ Lowest cost general purpose stainless steel. Wide use where corrosion is not severe.
416 12.00-14.00 0.15 S 0.15 min ¥ Free-machining version of Type 410.
420 12.00-14.00 0.15 min ¥ Similar variation of Type 410 but higher carbon produces higher strength and hardness.
430 14.00-18.00 0.12 * Most popular of the chromium types. Combines good corrosion and heat resistance and mechanical properties.
430 F 14.00-18.00 0.12 S 0.15 min * Free-machining version of Type 430.
¥ Series of high carbon types. Some basic composition with varying carbon content. Higher carbon produces higher strength and hardness but lower toughness. All Type 440 versions are corrosion resistant only in the hardened condition.
446 23.00-27.00 0.20 * Similar to Type 442 but Cr increased to provide maximum resistance to scaling.
15-5 PH 14.00-15.50 3.50-5.50 0.07 Cu 2.50-4.50 • Similar in properties and characteristics to 17-4 PH but has superior transverse ductility and toughness.
PH 15-7 Mo 14.00-16.00 6.50-7.75 0.09 Mo 2.00-3.00
Al 0.75-1.50
•• Special type similar to 17-7 PH but with higher strength.
17-4 PH 15.50-17.50 3.00-5.00 0.07 Cu 3.00-5.00 • Special type that combines excellent corrosion resistance…high strength and hardness… low temperature hardening and good fabrication characteristics.
17-7 PH 16.00-18.00 6.50-7.75 0.09 AL 0.75-1.25 •• Special ultra-high strength type with good formability and excellent fabricating characteristics.

Different Grades of Stainless Steel

There are several grades of stainless steel that have been developed over the years. These grades determine the composition and properties of each type of stainless steel. The two most common types are austenitic and ferritic stainless steels, which differ in their content of chromium and nickel as well as their magnetic properties. Other grades include martensitic, duplex, precipitation hardening (or PH), super austenitic, super duplex, and lean duplex stainless steel. Each grade has its own unique set of properties that make it suitable for specific applications.

  • Ferritic
  • Austenitic
  • Martensitic
  • Duplex

Benefits of Using Stainless Steel

In addition to its versatility and durability, there are many other benefits to using stainless steel. It is non-toxic, hygienic, highly heat resistant, easy to clean and maintain, aesthetically pleasing (in terms of color or texture), recyclable/reusable, energy efficient when compared with other metals such as aluminum or copper, cost-effective due to its long life cycle, low maintenance requirements (relative to other metals), relatively lightweight when compared with other metals such as aluminum or copper alloys, highly formable/malleable (which allows for shaping into complex forms), and more resistant than other metals when exposed to corrosive conditions such as salt water or certain chemicals/acids.


In conclusion, stainless steel is an incredibly useful material that has numerous applications thanks to its versatile composition—iron for strength; chromium for corrosion resistance; carbon for enhanced physical properties; plus various trace elements—and wide range of available grades depending on your needs. Whether you need something strong yet lightweight or durable yet economical – there’s likely a grade out there just right for your application! So if you’re looking for a material solution that offers superior performance while still being cost-effective – look no further than stainless steel!

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