300 vs 400 Series Stainless Steel: Which Triumphs?

Stainless steel is one of the prime materials known in the field of material science and engineering. It comprises of numerous properties that are beneficial for various demanding applications. This material exists in different series. In this article, we will discuss comprehensively the comparison and other aspects of austenitic SS and martensitic series of stainless steel. Both possess properties like corrosion resistance, durability, wear resistant, high strength and vice versa. So, despite your profession, get ready to know the wonder of both series in terms of their nature, properties, and applications.

What Is 300 Series Stainless Steel?

An austenitic alloy with chromium and nickel as main alloying elements present in their composition which allows them to be corrosion resistant even at elevated temperatures. Furthermore, they are non-magnetic in nature and have exceptional ductility due to which they have the capability to attain any shape (easily formable). This series consists of various grades starting from 301 and ending at 348. They are categorized based on their respective properties, applications, chemical stability, and their ability to react under certain environmental conditions. Moreover, they have numerous applications in medical, kitchen utensils, home appliances and in various industrial sectors.

Figure 1, 300 series stainless steel

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Is 300 Series Stainless Steel Magnetic

The marine grade stainless steel series comprises of austenitic nature which categorize them as non-magnetic in nature. Their FCC structure leads them to expose their paramagnetic behavior. Yet they can be magnetic when undergo welding process which introduces delta ferrite phase (BCC structure with ferromagnetic nature) in their microstructure that minimizes the risk of cracks during solidification in welded area.

Type 300 Series Stainless Steel

Table 1, Types of 300 series SS along with their properties and applications

What Is 400 Series Stainless Steel?

A series of hardenable stainless steel that comprise of high carbon compared as compared to 300 series along with the presence of chromium and nickel. They are well known for there properties such as good strength in addition to wear resistance but in some case, they may be more vulnerable to corrosion when exposed to aggressive environmental condition that contain chlorides. Furthermore, this series consist of two major categories that are ferritic and martensitic. Ferritic stainless steel offers good resistance to corrosion but are generally non hardenable alloys therefore possess less strength when compared to the martensitic category. 409 and 430 are typical types that belong to this family. On the other hand, 410,420 and 440 are martensitic stainless steel that have the capability to be hardened via heat treatment and offer more strength but unfortunately low corrosion resistance comparatively. Major application for 400 series includes industrial equipment, automative and kitchen utensils.

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Figure 2, 400 series stainless steel

Is 400 Series Stainless Steel Magnetic

This heat treatable series of stainless steel which is further divided into two major categories that is ferritic as well as martensitic stainless steel which allows them to have magnetic properties. However, the degree or intensity of magnetism surely depends on the specific grade of that particular series [9] [10].

Type 400 Series Stainless Steel

Table 2, Types of 400 series SS along with their properties and applications

300 and 400 Series Stainless Steel Machining Parts and Used

300 Series Stainless Steel

This material has great usage specifically for application relating with various machining parts, farm, and food processing equipment. This is possible due to several factors that are mentioned below:

• Their ability to sustain against chloride and acid containing environment.
• For food processing equipment, hygiene is one of the major factors that needs to address which is possible through this material as it is easy to sterilize and cleaning.
• Its capability to not react with food as well as beverages makes it harmless and free from contamination.
• The aesthetic appearance of this material makes it functional for both farm as well as food processing facilities.

Figure 3, Stainless steel food processing equipment

400 Series Stainless Steel

The 400 series of stainless steel is extensively being used in welded wire mesh due to number of reasons. Some are mentioned below:

• Moderate corrosion resistance required.
• Cost effectiveness
• Heat resistant.
• Ease of fabrication
• Magnetic properties

Figure 4, Welded wire mesh

These wires have great usage both in construction and agriculture along with various automotive components.

Customizable stainless-steel parts

Below is a general list comprising of customized stainless-steel parts. Not forgetting that this is a list of only a few parts. Both 300 and 400 series have numerous other applications based on the characteristics and properties they possess.

• Stainless Steel Linkages
• Stainless Steel Wheels
• Stainless Steel Brackets
• Stainless Steel Clamps
• Stainless Steel Manifolds
• Stainless Steel Mounting Plates
• Stainless Steel Pulleys
• Stainless Steel Shafts
• Stainless Steel Spacers
• Stainless Steel Valves
• Stainless Steel Flanges
• Stainless Steel Gears
• Stainless Steel Hinges
• Stainless Steel Levers
• Stainless Steel Latches

Figure 5, Customized stainless-steel parts

What is the Differences Between 300 and 400 series stainless steel?

Several factors based on which a detailed comparative analysis between both the series can be done are discussed one by one below:

Chemical Composition

Table 3, Chemical composition [19]

Corrosion Resistance

• 300 Series Stainless Steel: They are well known for their exceptional corrosion resistance by offering high quality protection against oxidation, rust as well as chemical corrosion in different environmental conditions. Secondly, the percentage of nickel in alloy composition is high which further paves way for this series to withstand environment that are exposed to aggressive condition including marine, food and chemical processing etc.

• 400 Series Stainless Steel: as far as corrosion resistant is concerned, the 400 series is less affective when compared to 300 series. They are only applicable where there are moderate conditions or in applications where resistance to corrosion is not a prime factor to tackle. Apart from that, they are susceptible to chlorides and acidic substances. Major demanding applications include kitchen utensils, cutlery and other industrial components which are less likely to be affected by rust.

Physical Properties

Table 4, Physical properties

Manufacturing process

Machinability

3xxx Series Alloys:

• Machining the 300 series stainless steel can be more challenging due to its higher nickel content and tendency to work-harden.
• lt requires slower machining speeds and more rigid tooling to achieve desired results effectively.

4xxx Series Alloys

• Machining the 400 series stainless steel is generally easier dueto its lower nickel content and higher hardness.
• It can be machined at higher speeds using conventional tooling methods.

Weldability:

• 300 Series SS

The 300 series stainless steel, such as austenitic grades like 304 and 316, offers good weldability with suitable welding techniques and filler materials.

Careful consideration and possibly preheating or post-weld heat treatment may be necessary to prevent sensitization and maintain corrosion resistance.

• 400 Series SS

Welding the 400 series stainless steel, especially higher carbon grades, may present challenges as it can be more prone to cracking.

Selecting appropriate welding parameters and filler materials is crucial to minimize distortion and maintain properties.

Heat Treatment:

300 Series SS

• The 300 series stainless steel, such as austenitic grades like 304 and 316, offers good weldability with suitable welding techniques and filler materials.
• Careful consideration and possibly preheating or post-weld heat treatment may be necessary to prevent sensitization and maintain corrosion resistance.

400 Series SS

• Welding the 400 series stainless steel, especially higher carbon grades, may present challenges as it can be more prone to cracking.
• Selecting appropriate welding parameters and filler materials is crucial to minimize distortion and maintain properties.

Stability in high temperature environments

The 300 series of stainless steel have the ability to remain stable under environments that are exposed to extreme elevated temperatures. Specifically, if we talk about the austenitic grades of this series such as 304 and 316 as well, both are capable enough to maintain their structure and integrity at high temperature in terms of mechanical properties and resistance against corrosion. For that reason, they are extensively used in applications including heat exchangers, furnace components and various exhaust systems.

The 400 series of stainless steel is limited to withstanding environmental conditions that are susceptible to only moderate temperatures. For instance, if we consider the example of 410 and 420 grades, they cannot bear high temperatures. Hence, their mechanical properties are challenged, and material degradation may occur when exposed to corrosion at such aggressive temperature conditions.

Cost

The stainless-steel grades comprising of 300 series are generally expensive as compared to 400 because of its exceptional properties especially when dealing with harsh and aggressive atmospheric conditions. In particular, 304 and 316 are way more expensive due to the presence of high nickel in their composition. Thus, providing exceptional corrosion resistance in marine, equipment that deal with food processing and other chemical processes.

On the other hand, stainless-steel grades that belong to 400 series are less expensive and cost friendly than 300 due to the lesser amount of nickel present in their percentage composition. Apart from that, simple processes are required for manufacturing purposes. Moreover, this series is affordable for applications where corrosion resistance is not a serious concern.

Summary Chart of AISI 300 and 400

Table 5, Summary Chart of AISI 300 and 400

Is 300 or 400 Stainless Steel Better?

We cannot conclude directly that this specific series of stainless steel is better than the other one because each series has its own unique properties, pros and cons associated with it and most importantly the applications it possesses. However, based on certain critical parameters, we can assume that the grade from this series is more beneficial according to the requirement of the application. So, in that context, if the required application demands high resistance to corrosion especially in aggressive environmental conditions, then 300 series is the better choice. On the other hand, if the application demands good strength and hardness while corrosion resistant is a secondary choice then in that case 400 series is the best choice.

Best Practices for Choosing Between 300 and 400 Series

Several factors are involved while considering the choice between 300 and 400 series for any specific application. To interpret the needs and requirements precisely, an accurate choice could be preferred. Below are some of the parameters guided before choosing any specific grade:

• Consult with Material Experts: Seek guidance from material experts, engineers, or suppliers who can provide valuable insights and recommendations based on their expertise and experience.
• Evaluate Corrosion Resistance Needs: Assess the environmental conditions your stainless steel will be exposed to.
• Consider Mechanical Properties: Determine the mechanical properties required for your application, such as hardness, strength, and ductility.
• Understand High Temperature Requirements: If your application involves exposure to high temperatures, consider the stability of the stainless steel at elevated temperatures.
• Understand High Temperature Requirements: If your application involves exposure to high temperatures, consider the stability of the stainless steel at elevated temperatures.