Alloy 4140 Round

Alloy 4140 Round


Std. cut tolerance -.00″/+.125″

Due to material handling and processing items may have light scratching. Raw Material is not meant to have a finished cosmetic look

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4140 Alloy

4140 Alloy is composed mostly of carbon and iron with a mixture of manganese, chromium, and molybdenum which increases the strength and hardenability. The 4140 Alloy is prepared for use through the annealing hardening and tempering processes. This metal is harder than regular steel but not very heavy. It also meets the qualifications of tool steel. Leaded grades of this steel are not recommended for applications with elevated temperatures. 4140 Alloy is often used for bolts, nuts, screws, machinery parts, conveyor belts, piston rods, and other steel products. JM Services carries 4140 Alloy Cold Finish pre hard (28-32 RC) stock in both flats and rounds.


  • Production cutting

Heat Treating

Before hardening 4140 Alloy, normalize the metal by heating it at 1675°F for approximately 30 minutes per inch of length. Allow the steel to air cool. To harden, heat the steel a second time at 1550°F for 30 minutes per inch of length. Quench in oil immediately after removing from the furnace.


Temperatures for forging 4140 Alloy range from 1700-2200°F.

Hot Working

You can hot work 4140 Alloy at 155-1900°F.


Anneal 4140 Alloy at 1600°F then slowly cool it in the furnace.

Cold Working

The annealed condition of this metal may be cold worked using conventional methods.


A lower tempering temperature produces increased hardness. Temper 4120 Alloy at 400-1200°F.


Both cold working, and heating and quenching methods will harden the 4140 alloy.


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