STAINLESS STEEL GRADES AND FAMILIES: EXPLAINED

Introduction to Stainless Steel Grades

As a part of our daily life interacting with loads of people we have understood perfectly, that all humans are not the same, everyone is different from one another in terms of nature, physical features, emotions, etc. And just like that When it comes to stainless steel, not all grades are created equal.

Whether you are looking for something to withstand extreme temperatures or need corrosion resistance for a specific project, understanding Stainless Steel Grades is key.

Thus, as Sumangal castings pvt. ltd. we are here to break it down in a way that makes sense, helping you choose the right material for the job. Lets take a deeper insight into the world of Stainless Steel Grades.

What Makes Up Stainless Steel?

Stainless steel is an alloy made up of a combination of metals. Key elements include iron ore, nickel, chromium, silicon, carbon, nitrogen, and manganese. The composition must have at least 10.5% chromium to be called stainless steel.

Stainless Steel Grades - Understanding the Various Types

Most stainless steel alloys are classified under two main categories:

• Families
• Grades

Divided by the specific properties & ratio of various metals in the stainless steel alloy, the stainless steel is divided into families and to understand what separates one stainless steel from others, you will have to understand the stainless steel grade.

Stainless Steel Families: Four Distinct Families with Unique Characteristics

• Austenitic Stainless Steel

• Duplex Stainless Steel

• Ferritic Stainless Steel

• Martensitic Stainless Steel

Decoding Stainless Steel Grades

Within each families of stainless steel, there are different grades that highlight key properties like toughness, resistance to corrosion, magnetism, and the specific mix of metals used. These differences help you choose the right type for your needs, whether its durability, strength, or resistance to the elements.

Grading Systems by Different Organizations

The stainless steel grading is done differently by every organisation. For example, the SAE (Society for Automotive engineers) has a 3 digit grading system, and ASTM (American Society for Testing and Materials) has its own 6 digit grading system.

We will understand the Stainless Steel Grades with an example in the further section, but first let us identify other organisations who use stainless steel grading systems.

• British Standards (BS)

• International Organization for Standardization (ISO)

• Japanese Industrial Standards (JIS)

• European Standard (EN)

• German Standard (DIN)

• Chinese Standard (GB)

We need to understand that each of these organizations has a different way of grading stainless steel, which means that a single stainless steel grade can be shown in multiple ways.

Example Identifying Stainless Steel Grade

Here we are taking the stainless steel from the austenitic family graded as 304 by the SAE. Here, the first digit describes the primary alloy element(3), and the second and third digits(04) describe the carbon percentage.

Now the same stainless steel 304 from the austenitic family will be expressed as -

• BS (British Standard) : 304S 15, 304S 16, 304S 18, 304S 25, En58E
• DIN (German Standard): X5CrNi18-9, X5CrNi18-10, X5CrNi19-9
• EN (European Standard): EN number: 1.4305, EN name: X8CrNiN18-9
• EN number: 1.4305,
• EN name: X8CrNiN18-9
• JIS (Japanese Industrial Standard): SUS 304, SUS 304-CSP
  
  

Characteristics of Common Stainless Steel Grades & Families