Call us for a Free Quote: 408-988-8582

Mon – Fri: 7:00 AM – 5:00 PM / PST

440 Stainless Steel Overview

440 Stainless Steel Overview

By STG Machine

Stainless steels play a pivotal role, offering a spectrum of properties tailored to diverse industrial applications. Among these, 440 stainless steel emerges as a notable contender, revered for its robustness, corrosion resistance, and machinability. This blog post delves into the intricacies of 440 stainless steel, encompassing its composition, mechanical attributes and more.

Understanding 440 Stainless Steel:

440 stainless steel, encompassing variants like 440A, 440B, and 440C, embodies a martensitic structure renowned for its elevated carbon content, typically ranging from 0.95% to 1.20%, and chromium content of approximately 16% to 18%. This amalgamation confers exceptional strength and hardness upon the material, rendering it a quintessential choice for applications necessitating robustness and durability.

  • 440A Stainless Steel:
    • Carbon Content: 0.65-0.75%
    • Hardness: Lower compared to 440B and 440C
    • Corrosion Resistance: Moderate
    • Applications: 440A stainless steel is commonly used for applications where moderate corrosion resistance and edge retention are required. However, its lower carbon content makes it less suitable for high-stress applications.
  • 440B Stainless Steel:
    • Carbon Content: 0.75-0.95%
    • Hardness: Higher than 440A but lower than 440C
    • Corrosion Resistance: Moderate
    • Application: 440B stainless steel’s enhanced hardness, compared to 440A, makes it a fitting choice for situations demanding elevated strength and wear resistance. This grade finds common usage in crafting knife blades, industrial bearings, and valve components.
  • 440C Stainless Steel:
    • Carbon Content: 0.95-1.20%
    • Hardness: Highest among the 440 series
    • Corrosion Resistance: High
    • Applications: Renowned for its exceptional hardness, wear resistance, and corrosion resistance, 440C stainless steel finds widespread use in critical applications. Examples include knife blades, bearings, and mold inserts.

Strength and Mechanical Properties of Stainless 440 Steel:

The strength of 440 stainless steel is a hallmark feature, underpinned by its high carbon composition. Following appropriate heat treatment, it achieves an impressive hardness, often reaching 58-60 HRC on the Rockwell Hardness Scale. This notable attribute renders it adept at withstanding wear and abrasion in demanding environments.

Chemical Composition:

The chemical composition of 440 stainless steel comprises a precise blend of elements, each contributing to its mechanical and corrosion-resistant properties. Primarily composed of carbon and chromium, with minor additions of manganese, silicon, phosphorus, and sulfur, its formulation is meticulously engineered to balance strength, corrosion resistance, and machinability.

the chemical composition of 440C stainless steel typically includes the following elements:

  • Carbon (C): 0.95-1.20%
  • Chromium (Cr): 16-18%
  • Manganese (Mn): ≤1.00%
  • Silicon (Si): ≤1.00%
  • Phosphorus (P): ≤0.040%
  • Sulfur (S): ≤0.030%

CNC Machining Considerations:

CNC machining of 440 stainless steel presents both advantages and challenges. While its high machinability facilitates precision engineering of intricate components, its elevated hardness poses challenges such as accelerated tool wear and heat generation during machining operations. Nevertheless, with adept tooling and coolant management, CNC machining can harness the material’s potential to yield intricately crafted components with superior dimensional accuracy.

Surface Finishes Attainable with 440C:

440C stainless steel offers a plethora of surface finishes, ranging from matte to mirror-like. Through techniques such as brushing, polishing, and bead blasting, varied textures and aesthetics can be achieved, catering to diverse design requirements and functional preferences.

Comparative Analysis within the 400 Series Stainless Steels:

In juxtaposition with its counterparts in the 400 series stainless steel family, such as 410 and 420, 440 stainless steel distinguishes itself through heightened carbon content and superior mechanical properties. While exhibiting similarities in corrosion resistance, 440 stainless steel stands out for its enhanced hardness, edge retention, and machinability, making it a preferred choice for applications demanding uncompromising performance.

Popularity of 440C

440C stainless steel is favored by engineers for several reasons:

  • High Hardness: 440C stainless steel exhibits the highest hardness among the 440 series, making it suitable for applications where wear resistance is paramount.
  • Corrosion Resistance: Compared to 440A and 440B, 440C stainless steel offers superior corrosion resistance.
  • Versatility: 440C stainless steel’s combination of high hardness, wear resistance, and corrosion resistance makes it versatile for a wide range of applications.
  • Precision Machinability: Despite its high hardness, 440C stainless steel can be machined to precise tolerances using CNC machining techniques.
  • Reliability: Mechanical engineers value 440C stainless steel for its consistent performance and reliability, ensuring the longevity and durability of engineered components in demanding applications.


In the continuum of stainless steel alloys, 440 stainless steel stands as a testament to ingenuity, embodying a harmonious amalgamation of strength, durability, and machinability. Its widespread adoption across diverse industrial domains underscores its indispensability in modern manufacturing processes, where precision, reliability, and longevity are paramount. Through meticulous engineering and innovative machining techniques, 440 stainless steel continues to redefine the boundaries of material excellence, propelling industries towards new frontiers of performance and resilience.

If you liked this blog post please take a look at some of our other related content:

Recent Stories

440 Stainless Steel Overview
March 27, 2024 5:47 pm
Understanding Stainless Steel 304
August 31, 2023 2:32 pm
Understanding 316 Stainless Steel
August 10, 2023 2:15 pm
CNC Machining Aluminum
August 2, 2023 11:12 pm