420 Stainless Steel: Properties, Applications & Supply 

420 Stainless Steel is a martensitic grade known for its high hardness, strength, and excellent polishability. As a heat-treatable alloy, its mechanical properties can be precisely tailored to meet demanding engineering requirements. This combination of features makes AISI 420 a preferred material for manufacturing cutting tools, surgical instruments, and wear-resistant components. Industries value this grade for its ability to achieve significant hardness while maintaining moderate corrosion resistance, offering a reliable solution for applications where edge retention and durability are critical. 

As a leading supplier and stockist of specialty metals in the UAE, Nifty Alloys LLC provides certified 420 Stainless Steel in various forms, including round bars and plates, to meet the exacting standards of our clients in the manufacturing, tooling, and engineering sectors. 

What is 420 Stainless Steel? 

420 Stainless Steel is a hardenable, martensitic stainless steel recognized for its versatility in engineering and manufacturing applications. As part of the martensitic family, it is defined by its ability to be heat treated, which provides increased hardness and strength. 420 grade is valued for its moderate corrosion resistance, outstanding polishability, and high mechanical performance. These characteristics make it a preferred choice for precision tools, cutlery, medical instruments, and components where hardness, durability, and surface finish are priorities. 

Properties of 420 Stainless Steel 

AISI 420 is classified as a martensitic stainless steel. Unlike austenitic or ferritic grades, martensitic steels are defined by their ability to be hardened and tempered through heat treatment. This capability stems from their higher carbon content, which allows for the formation of a martensite crystal structure upon quenching. 

The primary characteristics of 420 stainless steel include: 

• High Hardness: When hardened, it can reach up to 50 HRC, providing exceptional wear resistance. 
• Good Strength: It offers high tensile and yield strength, making it suitable for structural and mechanical components. 
• Excellent Polishability: The material can be polished to a superior mirror finish, a key requirement for surgical instruments and decorative applications. 
• Moderate Corrosion Resistance: It provides good resistance to atmospheric corrosion, fresh water, and mild acids, particularly in the hardened and polished condition. 

Key Features and Benefits 

Choosing 420 stainless steel provides several distinct advantages for specific industrial applications. Its unique combination of properties makes it a reliable and cost-effective material choice. 

High Hardness and Strength 

• The defining feature of 420 stainless steel is its ability to achieve high hardness and strength after heat treatment. This makes it ideal for applications requiring sharp, durable edges and resistance to deformation under stress. 

Excellent Polishability 

• Grade 420 can be polished to an exceptional mirror finish. This quality is crucial not only for aesthetic purposes but also for applications like surgical instruments, where a smooth surface is necessary to ensure hygiene and prevent contamination. 

Heat-Treatable for Enhanced Performance 

• The ability to harden and temper this alloy allows you to tailor its properties. You can optimize the balance between hardness, strength, and toughness to match the specific demands of your application, from cutting tools to durable machine components. 

Good Corrosion Resistance 

• In the hardened condition, 420 stainless steel exhibits good resistance to corrosion from the atmosphere, fresh water, foods, and mild alkalis or acids. For optimal performance, surfaces should be kept smooth and clean.