Stainless Steel 420 vs 304: A Comprehensive Material Guide

Choosing between stainless steel 420 and 304 largely depends on the specific needs of your application. Both grades have distinct properties that make them suitable for various industries. However, understanding their differences is crucial for selecting the optimal material. This article provides a detailed comparison, highlighting key attributes, applications, and recent research insights.

Key Properties of Stainless Steel 420 and 304

When comparing stainless steel 420 and 304, it is essential to understand their material characteristics and performance differences. Below is a table summarizing their key properties:

You might notice that the hardness units used for 304 and 420 differ. Let’s explain why.

*Stainless Steel Knowledge Corner: Difference in Hardness Units

HRC (Rockwell C): Used for harder materials, it applies a diamond cone or steel ball to measure indentation depth. Commonly used for tool steels and hardened steels.

HV (Vickers): Measures indentation with a diamond pyramid. It is commonly used for softer materials, such as thin sheets or softer metals.

HB (Brinell): Applies a large steel ball to the material’s surface, suitable for rough or uneven surfaces.

Hardness Comparison:

While HRC and HV are not directly comparable, a rough conversion can be made using common formulas:

50 HRCis approximately equal to 500 HV, indicating that Stainless Steel 420 has higher hardness.

300 HVis roughly equal to 30 HRC, so Stainless Steel 304 has significantly lower hardness than 420.

To make this comparison more intuitive, here’s a table summarizing the hardness values:

Alright, back to the point, let's continue to discuss the performance differences between 420 and 304.

In-Depth Comparison of 420 and 304

Korrosionsbeständigkeit

304 stainless steel offers significantly better corrosion resistance than 420. It excels in wet and salty environments, while 420 is more suitable for dry or mildly corrosive conditions. Studies show that chloride ions accelerate pitting in 304, while they have less impact on 420 in dry environments. 304’s resistance to rust in marine and industrial settings is far superior to that of 420.

Härte

420 achieves higher hardness (up to 50 HRC) after heat treatment, making it ideal for wear-resistant applications. In contrast, 304 prioritizes toughness and ductility. The increased hardness of 420 is especially useful for cutting tools and abrasion-resistant components.

Hitzebeständigkeit

304 can withstand continuous exposure up to 870°C, outperforming 420, which is limited to 650°C. Heat treatment enhances 420’s abrasion resistance but can reduce its machinability and weldability.

Machinability and Weldability

304 is easier to machine and weld, requiring no special post-weld treatments. In contrast, 420 requires preheating and post-weld heat treatments, and its machinability decreases as its hardness increases. Recent advancements in laser welding technologies have improved deformation control in thin stainless steel plates, benefiting 304 by ensuring minimal thermal distortion and precise dimensional control.

Anwendungsspezifischer Vergleich

Understanding how each grade performs in real-world applications is key to making an informed decision. Below are some examples:

Lebensmittelverarbeitungsgeräte

• 420: Its high hardness makes it ideal for cutting blades and other high-wear components, such as meat grinders and slicers. These applications require durability and edge retention.
• 304: Its superior corrosion resistance makes it perfect for acidic or salty environments, such as brewing tanks, milk pasteurizers, and wine fermentation vats, where hygiene and longevity are essential.

Studies show that 304 excels in chloride-rich environments, a common condition in food and beverage industries.

Chemische Ausrüstung

• 420: Suitable for handling mild acids and alkalis, often used in chemical mixers and pump shafts where moderate corrosion resistance is sufficient.
• 304: Performs excellently in more aggressive chemical environments, such as in storage tanks and pipes for acidic or saline solutions.

Research highlights that sulfate ions and other chemicals impact the pitting resistance of stainless steels, emphasizing 304’s superior performance in highly corrosive conditions compared to 420.

Medizinische Geräte

• 420: Its hardness and corrosion resistance make it ideal for surgical instruments, such as scalpels and forceps, requiring precision and durability.
• 304: Its ease of sterilization and superior corrosion resistance make it perfect for implantable devices, hospital beds, and surgical trays.

Advancements in laser welding have proven beneficial in minimizing deformation in thin plates, ensuring dimensional accuracy in intricate medical device designs.

Architectural and Decorative Uses

• 420: Used in limited applications such as durable door hardware and decorative panels in less corrosive environments.
• 304: Widely used for cladding, railings, and sculptures due to its aesthetic finish and outstanding resistance to environmental corrosion.

Automotive and Household Applications

• 420: Ideal for wear-resistant components like valve parts and pump rotors in vehicles.
• 304: Commonly found in car exhaust systems, kitchen sinks, and cookware, offering durability and corrosion resistance at an affordable cost.

Summary and Decision Guide

When choosing between stainless steel 420 and 304, consider the following application priorities:

Abschluss

If you still don't understand after reading this article, and want to ask which is better, 304 or 420 stainless steel?

What I can say is：

Choosing between stainless steel 420 and 304 depends on the specific needs of your application:

• Opt for 420when hardness, strength, and wear resistance are essential.
• Choose 304for superior corrosion resistance, formability, and weldability, especially in moist or corrosive environments.

Understanding the strengths and limitations of each material allows you to make an informed decision that optimizes both performance and cost-efficiency.

Whether it’s the hard 420 or the corrosion-resistant 304, we have both. If you're still uncertain about which material best suits your application, feel free to Kontakt our expert, Paige, at Sanmei Metal. We’ll provide professional advice tailored to your needs.