Industries

• Aerospace
• Tooling
• Chemical
• Oil and Gas
• Mining

Related Processes

Induction

Carbonitriding

Carburizing

Common Alloys

• Carbon Steels (e.g. 1045, 1144)
• Alloy Steels (e.g. 4140, 4340, 8630)
• Tool Steels (e.g. A2, D2, M4, H13)
• Martensitic Stainless Steels (e.g. 420, 440)

TMT Equipment/Variations
Parts can be hardened in air, endothermic, or vacuum furnaces.  Parts ran in air furnaces will exhibit some scaling due to the high temperature exposure to oxygen.  Parts ran in endothermic furnaces can be quenched in oil, polymer, or water quenches.  Parts ran in air furnaces can be quenched in polymer or water.  Parts ran in vacuum furnaces are cooled in the furnace with a gas or fan quench.

Applications

• ​Through hardening is one of the most widely applied heat treating processes.  It is also referred to as Quench and Temper.  The fundamental process that occurs is heating a part until above its critical temperature so that a phase change occurs to Austenite.  The part must then be rapidly cooled to form a Martensite microstructure.  Untempered Martensite is extremely brittle, so a subsequent tempering operation is needed.
• In general steels with a higher carbon content will be able to achieve higher maximum hardness.  Increasing the alloy content is required to improve the hardenability of a material.  A material with higher hardenability will be able to achieve higher hardness as the part size increases and will be more consistent surface to core.
• After hardening, parts are tempered to increase the toughness.  In general, as the tempering temperature is increased the hardness and strength will drop while the toughness will increase.
• Tool steels are a special group of steels that generally feature very high alloy contents.  They are frequently used in applications requiring extreme wear, hot work, or impact resistance.  Some will contain carbide forming alloys that create extremely hard spots within the material requiring special heat treating techniques to realize their full potential.

Associated Specs/Standards

• AMS 2759/1, 2759/2​, 2759/5, 2759, 6875
• ASTM A350, A668
• MIL 1684, 2710, 24093
• NACE MR0103, MR0175
• W-HTX

What To Consider When Specifying

• Material
• Furnace Atmosphere
• Hardness (if required)
• Mechanical Testing (if required)
• Specification (if required)

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Have more technical questions?  Contact a TMT engineer here.