These are oil-hardening steels of relatively high hardenability. Their chromium content provides good hardness penetration, and the molybdenum imparts uniformity of hardness and high strength. These grades are especially suitable for forging because they have self-scaling characteristics. They respond readily to heat treatment and are comparatively easy to machine in the heat treated condition. They resist creep in temperatures up to 1000°F and maintain their properties even after long exposure at these relatively high working temperatures. With a combination of such highly desirable properties as good strength and wear resistance, excellent toughness coupled with good ductility, and the ability to resist stress at elevated temperatures, it is understandable why these are widely used and highly successful alloy steels.

This material is also available as leaded steel. The addition of lead improves machinability without sacrificing other desirable properties, with the exception that the use of this material is not recommended for applications over 400°F, since at elevated temperature ductility is low.

The following specifications are generally applicable for 4140/42 Heat Treated Rounds: ASTM A 434, Grades BC and BD (Also stocked in A 193, Grade B7).
Unit of Measure

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Item #

Estimated Weight per Foot

Estimated Weight 12-Ft. Bar

N/A .2127 lb N/A 2.552 lb
N/A .4786 lb N/A 5.743 lb
N/A .6514 lb N/A 7.817 lb
N/A .8508 lb N/A 10.21 lb
N/A 1.077 lb N/A 12.92 lb
N/A 1.329 lb N/A 15.95 lb
N/A 1.914 lb N/A 22.97 lb
N/A 2.606 lb N/A 31.27 lb
N/A 3.403 lb N/A 40.84 lb
N/A 4.307 lb N/A 51.69 lb
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