443 vs 304 Stainless Steel: Key Differences Explained

Are you tired of the rising costs of stainless steel for your projects? This article explores a cost-effective alternative to Stainless Steel 304—SUS443. Learn how SUS443 offers superior corrosion resistance, better thermal conductivity, and significant savings. Dive in to find out how this innovative material can revolutionize your applications!

Table Of Contents

I. Price Comparison Between Stainless Steel 304 and 443

Material/ThicknessSUS443/2BSUS304/2B
0.31900025100
0.41850023600
0.51750022800
0.61680022500
0.71680022400
0.81660022200
0.91650022100
11650022100
1.21630021900
1.51610021700
1.81610021700
21600021700
2.21600021700
2.5160001700
31600021700
>3.01700023200

Unit: CNY/Ton.

II. Introduction to 304 Stainless Steel and 443 Stainless Steel

304 Stainless Steel

304 Stainless Steel, commonly referred to as Stainless Steel 304, is one of the most widely used types of stainless steel. To maintain its inherent corrosion resistance, stainless steel must contain at least 12% chromium. In the case of 304 stainless steel, it also includes more than 8% nickel, which enhances its corrosion resistance and formability.

Applications

Stainless Steel 304 is prevalent in various applications due to its excellent properties. It is commonly found in:

  • High-end stainless steel tableware: Its corrosion resistance makes it ideal for cutlery and kitchen utensils.
  • Outdoor railings: The material’s durability and resistance to environmental factors make it suitable for outdoor use.
  • Manufacturing equipment and parts: Industries that require materials with good combined performance, such as corrosion resistance and formability, often use Stainless Steel 304.

Market Dynamics

The international price of nickel, a key component of Stainless Steel 304, is subject to constant fluctuations. Since nickel is a limited resource, its price volatility directly impacts the cost of 304 stainless steel. This rising trend in nickel prices has become a significant factor limiting the development and broader adoption of Stainless Steel 304.

443 Stainless Steel (21CT)

Given the instability in the international market for stainless steel raw materials and the increasing competition, there is a growing demand to reduce material costs. End users are becoming more specific in their requirements for stainless steel materials, seeking alternatives that can offer similar or better performance at a lower cost.

Development of 21CT (SUS443)

To address these challenges, our company, in collaboration with Japan’s JFE and TISCO, has developed a new product: 21CT, branded as SUS443. This development aims to provide a cost-effective alternative to Stainless Steel 304 without compromising on quality.

  • Development Timeline:
    • September 2005: Successful development of 21CT.
    • January 2006: Official sample pieces provided for customer testing.
    • November 2006: Widespread acceptance and use by consumers.

The introduction of 21CT (SUS443) represents a significant advancement in the stainless steel industry, offering a viable alternative to Stainless Steel 304. This new material addresses the urgent need for cost reduction while maintaining high performance, making it a valuable solution in the current market landscape.

III. Main Features of 443 Stainless Steel (21CT)

1. Enhanced Chromium Content

443 stainless steel, also known as 21CT, contains 21% chromium, which significantly improves its corrosion resistance. This level of chromium content provides corrosion resistance comparable to that of stainless steel 304, and its pitting resistance surpasses that of 304. This makes 21CT an excellent choice for applications requiring high resistance to corrosive environments.

2. Reduced Impurities and Added Elements

The reduction of impurities such as carbon and nitrogen, coupled with the addition of elements like titanium and copper, further enhances the corrosion resistance of 21CT. Titanium stabilizes the steel, preventing the formation of chromium carbides at grain boundaries, which can lead to intergranular corrosion. Copper improves resistance to certain types of corrosion and enhances the overall durability of the material.

3. Ferritic Stainless Steel Characteristics

21CT belongs to the ferritic 400 series of stainless steels, specifically identified by the brand number SUS443. Ferritic stainless steels are known for their good mechanical properties and resistance to stress corrosion cracking. 21CT exhibits superior mechanical properties compared to SUS430, making it a robust option for various applications.

4. Cost-Effective Alternative

One of the significant advantages of 21CT is its cost-effectiveness. Since it does not contain nickel, its price is approximately 30% lower than that of stainless steel 304. This makes 21CT an attractive option for projects where budget constraints are a consideration, without compromising on performance.

5. Superior Thermal Conductivity

21CT offers about 30% higher thermal conductivity compared to stainless steel 304. This characteristic, along with its good magnetic conductivity, makes it particularly advantageous for applications in cooking products and other scenarios where efficient heat transfer is essential.

6. Reduced Processing Costs

Due to the inherent characteristics of ferritic stainless steel, components made from 21CT that undergo deep processing are less likely to experience delayed fracture caused by the release of internal stress. As a result, annealing treatment is generally not required, which effectively reduces processing costs and simplifies manufacturing processes.

In summary, 443 stainless steel (21CT) combines excellent corrosion resistance, superior mechanical properties, cost-effectiveness, and enhanced thermal conductivity, making it a highly versatile and valuable material for a wide range of industrial applications.

IV. Application Fields of Stainless Steel 443 (21CT)

Stainless Steel 443, also known as 21CT, is a ferritic stainless steel that offers excellent corrosion resistance, good formability, and high-temperature strength. Its unique properties make it suitable for a wide range of applications across various industries. Below is an overview of its primary application fields:

Kitchenware

Stainless Steel 443 is widely used in the kitchenware industry due to its corrosion resistance and ease of cleaning. Common applications include:

  • Dish Sinks: Durable and resistant to rust, making them ideal for constant exposure to water.
  • Barbecue Stoves: Withstands high temperatures and resists corrosion from food acids.
  • Kitchen Equipment: Used in various kitchen appliances and tools.
  • Kettles: Provides a safe, non-reactive surface for boiling water.
  • Cooktops: Heat-resistant and easy to clean.
  • Tableware: Non-reactive and maintains a polished appearance.
  • Range Hoods: Resistant to grease and easy to maintain.
  • Stove Panels: Durable and heat-resistant.
  • Cooking Pots: Non-reactive and maintains a polished finish.

Appliances

The appliance industry benefits from the durability and aesthetic appeal of Stainless Steel 443. Common applications include:

  • Dishwashers: Resistant to detergents and water.
  • Rice Cookers: Provides a non-reactive surface for cooking.
  • Microwaves: Durable and easy to clean.
  • Washing Machines: Corrosion-resistant and durable.
  • Freezers: Maintains structural integrity at low temperatures.
  • Mixers: Durable and easy to clean.
  • Coffee Machines: Non-reactive and maintains a polished finish.

Transportation

In the transportation sector, Stainless Steel 443 is valued for its strength and resistance to corrosion. Common applications include:

  • Refrigerated Containers: Maintains integrity in cold environments.
  • Automotive Exhaust System Parts: Resistant to high temperatures and corrosion.
  • Heat Exchangers: Efficient heat transfer and corrosion resistance.

Construction

The construction industry utilizes Stainless Steel 443 for its durability and aesthetic appeal. Common applications include:

  • Elevators: Durable and maintains a polished appearance.
  • Escalators: Resistant to wear and corrosion.
  • Roofs: Durable and resistant to weathering.
  • Door and Window Accessories: Maintains a polished appearance and resists corrosion.
  • Miscellaneous Hardware: Durable and resistant to wear.
  • Decorative Pipes: Maintains a polished appearance and resists corrosion.
  • Construction Hardware: Durable and resistant to wear.

Others

Stainless Steel 443 is also used in various other applications due to its unique properties. Common applications include:

  • ERW Pipes: Durable and resistant to corrosion.
  • Water Tanks: Maintains integrity and resists corrosion.
  • Water Pipes: Durable and resistant to corrosion.
  • Combustion Nets: Resistant to high temperatures.
  • Barbecue Nets: Durable and resistant to high temperatures.
  • Mufflers: Resistant to high temperatures and corrosion.

Current Application Fields in Our Company

In our company, Stainless Steel 443 materials, primarily in the form of stainless steel plates, are mainly used in the following industries:

  • Elevator Industry: Utilized for its durability and aesthetic appeal.
  • Small Appliance Industry: Valued for its corrosion resistance and ease of cleaning.
  • Food Equipment: Non-reactive and easy to maintain.
  • Tableware Industry: Maintains a polished appearance and is non-reactive.
  • Kitchen Engineering: Durable and resistant to corrosion and high temperatures.

Stainless Steel 443 continues to be a versatile and valuable material across multiple industries, providing a combination of durability, corrosion resistance, and aesthetic appeal.

V. Comparative Analysis of Chemical Composition of Stainless Steel 304 vs 21CT

Steel Type21CTSUS304
Chromium2118.2
Nickel8.1
Molybdenum
Titanium0.3
Carbon0.0080.06
Nitrogen0.010.04
Copper0.43

*21CT increases the chromium content to 21%, thus providing better corrosion resistance, and additionally includes titanium and copper elements.

*Titanium can enhance the resistance to intergranular corrosion and improve weldability.

*Copper can improve resistance to acidic substances.

VI. Comparison of the physical properties of SUS304 and SUS443 (21CT)

Steel Type21CTSUS304
Density(g/cm37.747.93
Density(10-6Ω·cm)5870
MagnetismYesNo
Specific Heat 25℃(J/kg·℃)440500
Thermal Conductivity 100℃(W/m·℃)22.516.2
Thermal Expansion Rate 20-100℃(10-6/℃)10.517.3
Young’s Modulus (Gpa)204193

Compared to 304, 21CT has: Lower density, allowing for an approximately 2.5% increase in material area for the same weight, better thermal conductivity, less thermal expansion, magnetism, and excellent properties suitable for use with induction cookers.

VII. Comparison of Mechanical Properties between SUS304 and 443 (21CT)

Steel TypeSUS443SUS304
Yield Strength (MPa)305260
Tensile Strength (MPa)483645
Extension Rate (%)3160
Average R Value1.31
Hardness (Hv)161185
Cone Cup Protrusion (mm)38.637.7
Bendability (Bend Angle 180°)Good(R=0T)Good(R=0T)

The R value is an indicator of the deep drawing performance of the material. The higher the R value, the better the deep drawing performance!

VIII. Comparison of thermal conductivity between SUS304 and 21CT

Test result graph for boiling 2 liters of water.

Conclusion: When heating with gas or an induction stove, the thermal conductivity of 443 is superior to that of stainless steel 304!

IX. Comparison of the welding performance between 304 and 443 (21CT):

CombinationTIG Welding  MIG Welding  Arc Welding
Welding of the same type: 21CT and 21CT
Welding of different types: 21CT and SUS304
  • □: Corrosiveness will not decrease or decrease very slightly
  • ■: Corrosiveness will decrease

Note: For more detailed welding technical data and welding skills, you can contact our company to obtain them.

X. Comparison of Corrosion Performance Results between 304 and 443 Stainless Steel Plate

Steel Type    Cyclic Corrosion TestingSalt Spray Test (NSS)Exposure Test Corrosion of Welded Parts
SUS443     
SUS304     

Methods to test corrosion resistance:

1. Surface #600 polished stainless steel plate, saltwater spray (5% NaCl, 35℃, 2hr) → dry (60℃, 4hr) → moisten (40℃, 2hr), repeat 30 times.

2. Surface #600 polished stainless steel plate, neutral saltwater spray (5% NaCl, 35℃), 1000 hours.

3. Surface #600 polished stainless steel plate, exposed for 9 months in Chiba Prefecture, Japan, 10 meters from the shore, with sea salt adsorption quantity of 0.25mg.dm-2.day-1.

4. TIG welding, plate thickness is 0.8mm, contact start arc welding, using argon gas for protection, and polished with surface #600 after welding.

XI. Comparison of Stress Corrosion Cracking Tests Between SUS304, SUS304, and SUS443

Comparison of Stress Corrosion Cracking Tests:

Steel Type 304 Stainless Steel443 Stainless Steel
Presence or Absence of a BreakBreakage occurs within ≤15 hours.No breakage after 100h test
Appearance After Testing  

Condition: 42% MgCl2U, JIS G 0576 shape bending

Conclusion: 304 stainless steel may undergo stress corrosion cracking, but 443 stainless steel is not at risk of this occurrence.

XII. 443 Certified

EU ROHS CertificationCompliant with the European Union’s environmental protection standards (SGS certified)
International Health CertificationConforms to the requirements of GB-9684-1988 “Hygienic Standard for Stainless Steel Food Utensils and Containers”
Germany LFGB CertificationComplies with German food and commodity laws, and meets the requirements for metal release from stainless steel tableware
US FDA CertificationMeets the food safety regulatory standards of the United States, and the requirements for metal release from stainless steel tableware
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Shane
Author

Shane

Founder of MachineMFG

As the founder of MachineMFG, I have dedicated over a decade of my career to the metalworking industry. My extensive experience has allowed me to become an expert in the fields of sheet metal fabrication, machining, mechanical engineering, and machine tools for metals. I am constantly thinking, reading, and writing about these subjects, constantly striving to stay at the forefront of my field. Let my knowledge and expertise be an asset to your business.

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