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Common Valve Materials What is the Difference Between 304 and 321 Stainless Steel?

November 30,2023

As one of the important components in the field of fluid control,  valve material selection is crucial to the performance and reliability of the valve. In the field of valve manufacturing, stainless steel is one of the commonly used materials, among which 304 stainless steel and 321 stainless steel are widely used. This article will introduce the differences between these two stainless steel materials to help readers better understand their characteristics and applicable scenarios.

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Introduction

As one of the important components in the field of fluid control, valve material selection is crucial to the performance and reliability of the valve. Suitable materials can improve the corrosion resistance, mechanical strength, wear resistance and other properties of the valve, thereby extending the service life of the valve. When selecting materials, factors such as the properties of the fluid, temperature, and pressure need to be taken into consideration, as well as comprehensive considerations based on specific application scenarios.

Understand 304 stainless steel

304 stainless steel is one of the most common stainless steel materials, consisting of 18% chromium and 8% nickel. This material is very corrosion-resistant and can withstand the attack of most chemicals while possessing good strength and plasticity. In valve manufacturing, 304 stainless steel is often used to manufacture ball valves, butterfly valves, globe valves, etc.

The advantage of 304 stainless steel is that it has excellent corrosion resistance, mechanical strength and processability, and can meet most valve manufacturing needs. However, 304 stainless steel also has some limitations, such as being prone to deformation and intergranular corrosion in high temperature environments.

Understand 321 stainless steel

321 stainless steel is a titanium-stabilized stainless steel material composed of 18% chromium, 11% nickel and 0.6% titanium. Compared with 304 stainless steel, 321 stainless steel is more stable in high temperature environments and has better corrosion resistance. In the field of valve manufacturing, 321 stainless steel is often used to manufacture high-temperature and high-pressure valves and chemical processing valves.

The advantage of 321 stainless steel is that it performs well in high temperature environments and can withstand corrosion and oxidation in high temperature and high pressure environments. In addition, 321 stainless steel also has good weldability and wear resistance. However, since the addition of titanium will increase the material cost, the cost of using 321 stainless steel to manufacture valves is relatively high.

Comparison of 304 and 321 stainless steel

In order to better understand the differences between these two materials, a comparative analysis will be conducted below.

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Refrigeration HONGSEN Stainless Steel vibration eliminator

Physical properties comparison

Strength: The yield strength of 304 stainless steel is 215MPa and the tensile strength is 515MPa; while the yield strength of 321 stainless steel is 205MPa and the tensile strength is 515MPa.

Corrosion resistance: Although both materials have good corrosion resistance, 321 stainless steel performs better in some special environments. For example, in acidic environments, 321 stainless steel can withstand higher temperatures and pressures.

Magnetism: 304 stainless steel is a non-magnetic material, while 321 stainless steel is partially magnetic.

Thermal stability comparison

Because 321 stainless steel contains titanium, it is more stable in high temperature environments. When the temperature exceeds 800 degrees Celsius, 321 stainless steel can still maintain good structural stability, while 304 stainless steel is prone to problems such as deformation and intergranular corrosion. Therefore, in high temperature and high pressure environments, choosing 321 stainless steel material can better ensure the performance and reliability of the valve.

Choices in practical applications

In actual applications, how to choose 304 and 321 stainless steel materials depends on the specific application scenario. If you need to manufacture corrosion-resistant valves or cryogenic valves, 304 stainless steel is an ideal choice. For valves used in high temperature and high pressure environments, or chemical processing valves that require high corrosion resistance, choosing 321 stainless steel is a wiser choice.

Conclusion

This article introduces the application and characteristics of 304 and 321 stainless steel materials in valve manufacturing. Although both materials have good corrosion resistance and mechanical properties, they differ in areas such as thermal stability and corrosion resistance. When selecting materials, it is necessary to comprehensively consider the specific application scenarios and select based on the advantages and disadvantages of the materials. For special application scenarios such as manufacturing high-temperature and high-pressure valves and chemical processing valves, choosing 321 stainless steel material can better ensure the performance and reliability of the valve.


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