General Properties
Alloy 410 is a hardenable, straight-chromium stainless steel which combines the superior wear resistance of high carbon alloys with the excellent corrosion resistance of chromium stainless steels. Oil quenching this alloy from temperatures between 1800°F to 1950°F (982-1066°C) produces the highest strength and/or wear resistance as well as corrosion resistance. A range of as-quenched hardnesses is achieved by varying the carbon level from .15% maximum in Alloy 410.

This alloy is used where strength, hardness, and/or wear resistance must be combined with corrosion resistance.

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Applications
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 carbine 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 straight-chromium stainless steels.

Applications for Alloy 410 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.

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Chemical Composition
Typical values (Weight %)

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Mechanical Properties
Typical compositions, annealed mechanical properties, and hardening response for Alloy 410 martensitic stainless steel are presented below.

Modulus of Elasticity
29 x 10⁶ psi (200 GPa)

Data shown below give typical mechanical properties of martensitic stainless steels obtained with various drawing temperatures after austenitizing at 1800-1950°F (982-1066°C) followed by an oil quench and a two-hour temper. Heat-to-heat variations can be anticipated.

Typical Mechanical Properties of Heat Treated Alloy 410 Martensitic Stainless Steel

*See Heat Treatment section for annealing information.

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Physical Properties
The values reported below are typical for Alloy 410 in the annealed condition.

Modulus of Elasticity:
29 x 10⁶ psi (200 GPa)

Specific Gravity:
7.65

Density:
0.276 Lbs/in3

Specific Heat:
.11 Btu/lb. ∑ °F

Thermal Conductivity at 212°F (100°C):
14.4 Btu/(hr ∑ ft ∑ °F)
24.9 W/m ∑ K

Electrical Resistivity:
56 Microhm-cm 68°F (20°C)

Coefficient of Thermal Expansion:
68 - 392°F, 5.9 x 10^-6 in/in°F
20 - 200°C, 10.5 x 10^-6 cm/cm/°C
68 - 1112°F, 6.5 x 10^-6 in/in/°F
20 - 600°C, 11.6 x 10^-6 cm/cm/°C

Melting Range:
2700 - 2790°F
1482 - 1532°C

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Corrosion Resistance
Alloy 410 exhibits good corrosion resistance to atmospheric corrosion, potable water, and to mildly corrosive chemical environments because of its ability to form a tightly adherent oxide film which protects its surface from further attack.

Its exposure to chlorides in everyday-type activities (e.g., food preparation, sports activities, etc.) is generally satisfactory when proper cleaning is performed after exposure to use.

General Corrosion Behavior Compared With Other Nonaustenitic Stainless Steels*

*Hardened martensitic grades were tested after tempering at 400°F (204°C).

As shown in the above table, these alloys have good corrosion resistance to low concentrations of mild organic and mineral acids.

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Fabricating Properties
Machining
Alloy 410 should be machined in the annealed condition using surface speeds of 60 to 80 feet (18.3 – 24.4 m) per minute.

Surface Preparation
For maximum corrosion resistance to chemical environments, it is essential that the stainless steel surface be free of all heat tint or oxide formed during forging, annealing, or heat treating. All surfaces must be ground or polished to remove any traces of oxide and surface decarburization. The parts should then be immersed in a warm solution of 10-20% nitric acid to remove any residual iron. A thorough water rinse should follow the nitric acid treatment.

Structure
In the annealed condition, Alloy 410 consists of ferrite and carbides. When this alloy is heat treated at high temperatures [1800°F-1950°F (982-1066°C)], austenite will form and transform to martensite upon cooling to room temperature (i.e., air cool or oil quench). The hardness of the martensite will increase with increasing carbon content to a point where the martensite becomes saturated with carbon. Carbon also combines with carbide formers such as chromium to form chromium carbides which are dispersed throughout the microstructure to provide added wear resistance, as does higher hardness.

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Heat Treating
To anneal this alloy, heat to 1500°F-1550°F (815-842°C) and hold for one hour per inch of thickness and furnace cool to room temperature. Such annealing should produce a Brinell hardness of 126-192 HB in Alloy 410 material.

A hardening heat treatment is necessary to bring out the maximum hardness and wear resistance. Since these materials absorb heat very slowly, they should be heated gradually and allowed to remain at temperature long enough to ensure uniform temperature in thick sections. For maximum strength, hardness, and corrosion resistance, slowly heat the alloy to 1800°F (982°C) and quench to room temperature in oil.

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