BLUE SHEET - Martensitic Stainless Steels Types 410, 420, 425 Mod, and 440A

Oct 13, 2026

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Allegheny Ludlum martensitic stainless steels (Types 410, 420, 425 Modified, and 440A) are hardenable, straight-chromium grades combining high wear resistance from higher carbon with chromium-based corrosion resistance. Oil quenching at 1800–1950°F (982–1066°C) followed by tempering yields high strength and/or wear resistance with hardness varying by carbon content. Typical chemical composition ranges, annealed mechanical properties, hardening responses, product forms, and application guidance are provided, including cutlery processing effects such as fine blanking limits and “comet-tails” risk in Type 440A.

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General Properties

Applications

Product Form

Chemical Composition

Mechanical Properties

Typical Mechanical Properties After Heat Treatment

TECHNICAL DATA BLUE SHEET Martensitic Stainless Steels Types 410, 420, 425 Mod, and 440A GENERAL PROPERTIES Allegheny Ludlum Types 410, 420, 425 Modified, and 440A (see composition on Page 2) are hardenable, straight-chromium stainless steels which combine superior wear resistance of high carbon alloys with the excellent corrosion resistance of chromium stainless steels. Oil quenching these alloys from temperatures between 1800°F to 1950°F (982-1066°C) produces the highest strength and/or wear resistance as well as corrosion resistance. Arange of as-quenched hardness is achieved in these alloys by varying the carbon level from 0. 15% maximum in Type 410 to 0 .60-0.75% in Type 440A. These alloys are used where strength, hardness, and/ or wear resistance must be combined with corrosion resistance. APPLICATIONS A major use for these grades of heat treatable stainless steels is in cutlery. Depending on the customer's end-use requirements, cutlery alloys are usually selected with respect to heat treating response, mechanical properties and fabricating characteristics. When sufficient amounts of carbon are added to straight-chromium stainless steels, the alloy then has the capability to transform its microstructure through proper heat treatment (hardening) into one that will possess optimum strength, hardness, edge retention, and wear resistance. The presence of sufficient chromium will impart the necessary corrosion resistance and form chromium carbide particles that enhance the wear resistance of the given alloy. The higher the carbon content, the greater the amount of chromium carbide particles, and the greater the strength and hardness for heat treatable straightchromium stainless steels. When blanking cutlery parts from annealed raw material stock, Types 410, 420, and their higher carbon versions (Types 410HC and 420HC) will usually exhibit hardness, yield strength, and tensile strength that are low enough for fine blanking purposes. However, Type 440A is not readily amenable to fine blanking due to its higher strength and hardness in the annealed condition; and therefore, could require more powerful presses to blank parts. In addition, the presence of large primary carbides in Type 440A would tend to reduce die life. When buffing blanked parts, the higher hardness of Type 440A in the heat treated condition (hardened) would mean less residual buffing lines on the surfaces of parts but the large primary carbides could be dislodged during buffing which would produce scratches called “comet-tails”. Stainless steels lower in carbon content are essentially free of "comet-tails". Other applications for these grades include dental and surgical instruments, nozzles, valve parts, hardened steel balls and seats for oil well pumps, separating screens and strainers, springs, shears, and wear surfaces. PRODUCT FORM These alloys are available as plate, sheet, strip and flat bars. Data are typical and should not be construed as maximum or minimum values for specification or for final design. Data on any particular piece of material may vary from those shown herein. CHEMICAL COMPOSITION | Stainless
Steels | Element in Weight Percent | | | | | | | | | --- | --- | --- | --- | --- | --- | --- | --- | --- | | | Carbon | Manganese | Silicon | Chromium | Molybdenum | Nickel | Sulfur | Phosphorus | | Type 410* | 0.15 max | 1.00 max | 1.00 max | 11.50-13.50 | -- | 0.50 max | 0.03 max | 0.04 max | | Type 420** | 0.15-0.40 | 1.00 max | 1.00 max | 12.00-14.00 | --- | 0.50 max | 0.03 max | 0.04 max | | Type 425 Mod | 0.50-0.55 | 1.00 max | 1.00 max | 13.00-14.00 | 0.80-1.20 | 0.50 max | 0.03 max | 0.04 max | | Type 440A | 0.60-0.75 | 1.00 max | 1.00 max | 16.00-18.00 | 0.75 max | 0.50 max | 0.03 max | 0.04 max | *A higher carbon version of Type 410 is also available called Type 410HC (nominal 0.21% C) . **A higher carbon version of Type 420 is also available called Type 420HC (nominal 0.44% C) . MECHANICA

FAQs

What oil-quenching temperature range is recommended for these martensitic stainless steels?

These alloys are oil quenched from about 1800°F to 1950°F (982–1066°C) to achieve the highest strength and/or wear resistance while maintaining corrosion resistance.

How does carbon content influence hardness and wear resistance across the listed types?

Hardness and wear resistance are achieved by varying carbon level: lower carbon in Type 410 and higher carbon in Type 440A increases chromium carbide content, strengthening and increasing hardness.

Why is Type 440A less suitable for fine blanking than Types 410 and 420?

Type 410/420 and higher-carbon variants may have low enough hardness in the annealed condition for fine blanking, while Type 440A is not readily amenable due to higher annealed strength and hardness, which can require more powerful presses and reduce die life due to primary carbides.

Oct 13, 2026

Upload by Levi