Considerations When Choosing Stainless Steel Grades

Stainless steel alloys are known for their decorative appeal and enhanced corrosion resistance, making them some of the most sought-after metal alloys in existence. Providing an abundance of beneficial qualities that cannot be matched by any other metal, there are several different types of stainless steel grades that are used for countless commercial and industrial applications.

Stainless Steel Grades

With so many different stainless steel grades to choose from, finding the best option for your specific requirements can feel daunting. Luckily, with some research and a basic understanding of your project’s needs, the correct stainless steel grade is never far from reach.
Whether you are pondering the most common stainless steel grades of 304, 314, 316, or perhaps another alloy, several considerations should be met before making a final decision. The following is a list of some of the more common stainless steel alloys that are used throughout the world:

• Austenitic – These make up 70% of total worldwide stainless steel production.
  • 200 series
  • 303
  • 304 & 304L
  • 316
  • 316L
• Ferritic – Highly corrosion resistant but less durable than austenitic stainless steel grades.
  • 409
  • 416
  • 430
  • 439
• Martensitic – Extremely strong and tough.
  • 410
  • 440C
• Precipitation-Hardening Martensitic – Extreme corrosion resistance.
  • 17-4
  • 15-5
• Duplex – Mixed microstructure of austenite and ferrite.
  • 2205
  • 2207

Consideration Factors When Choosing Stainless Steel Grades

With so many different grades of stainless steel to choose from, it can be challenging to know which is best for your unique specifications. However, understanding the properties and characteristics of some of the more common stainless steel alloys may make the decision more accessible than you think. Some of the considerations that should be taken into account when choosing your stainless steel grade include the following:

Corrosion Resistance

It is commonly understood that Stainless steel is well-regarded for its corrosion resistant properties. However, not all stainless steel alloys maintain the same levels of corrosion resistance. Austenitic stainless steel, such as 316, offers the highest level due to the presence of chromium alloys. Martensitic and ferritic stainless steel grades are the less expensive options that still provide good corrosion resistance.
Heat treatment will also affect how certain stainless steels respond. Martensitic alloys may be the best choice if your project requires heat treatment and enhanced corrosion resistance. Since they don’t harden, austenitic and ferritic steels do not provide the best options for heat treatment.
The 300 series has superior corrosion resistance and is easy to fabricate. They are used predominantly in the automotive, aerospace, and construction industries.

Operating Environment

Whether it’s temperature, low pH, stressors, or crevice corrosion, the operating environment of the stainless steel will affect its overall performance. The best all-around performing stainless steel alloys are 304 and 316. They provide the best strength, toughness, and corrosion resistance across a broad temperature range. Type 316 has molybdenum which resists chloride ions associated with marine and chemical applications.

Strength & Ductility

Stainless steel alloys containing chromium and nickel provide increased strength and ductility. Coupled with enhanced corrosion resistance characteristics, stainless steel grades such as 420 are hardened and stress relieved, providing nearly triple the tensile strength of 304. Stainless steel grades with high tensile strength tend to be a better fit for heavy-duty applications involving heavy loads.

Process Temperatures

One of the easiest ways to identify a stainless steel grade is by looking at its maximum use temperature or melting point. If a specific stainless steel grade does not maintain the melting point that your specifications require, then it can be easily eliminated from the potential candidate pool. Since heat-intensive processes are more likely to push the limits of a stainless steel alloy’s temperature tolerance, it is essential to understand each alloy’s heat treatment or temperature-based sterilization process.

Weldability & Formability

Stainless Steel features such as weldability and formability should also be considered before choosing the appropriate alloy for your project. Lower-end stainless steel grades tend to crack or corrode when welded. Austenitic alloys provide the best weldability. Alloy 304L offers lower carbon, and 347 stainless steel provides a niobium stabilizer that prevents cracking and corrosion. Stainless steel grades 430 and 439 also offer good weldability, while martensitic alloys should be avoided if welding is necessary.
Applications that require good formability need an austenitic grade of stainless steel, such as 304, or a ferritic grade, like 430. Martensitic grades, like 410, should not be considered since they’re brittle and weak.

Choosing the Right Stainless Steel Grade for Your Project

With many available options, the stainless steel alloy best suited for your project will depend on multiple factors. Understanding your project’s specifications and requirements will automatically eliminate the stainless steel grades that do not meet those standards. From there, it is ultimately about preference and the features of most significant interest to you. Research some of the more popular stainless steel grades, and experiment until you find the one that provides the benefits you need.

The IMS Difference

What separates IMS from other metals companies? With an abundance of metal options and customer service that is second to none, IMS has you covered with the following service advantages:

• Next-day delivery of processed material via our trucks
• Same-day pick-up in Will-Call
• No minimum purchase
• Support of Just-in-Time manufacturing processes
• Salespeople that act as an extension of your purchasing department (we will get any metal products you need)
• Material management (stocking and delivery on a scheduled basis)
• Credit lines with good terms
• Knowledgeable staff that knows metal

 
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