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FLEXOR® Superior Steel Alternative to

4120 Alloy Steel

Pennsylvania Steel Corporation offers an alternative to AISI 4120 alloy steel.

We produce FLEXOR® steel to provide similar, if not superior, chemical and mechanical properties to 4120 alloy steel. These properties allow FLEXOR® steel to be used effectively for applications that require an excellent strength to weight ratio coupled with high strength, hardness and wear resistance as an alternative to 4120 steel. These include Structural Tubing, Frames, Gears, Piston Pins, Crankshafts, Clutch and Flywheel Components used as Aircraft, Aerospace and Automotive Components.

Being a proprietary grade, Pennsylvania Steel ensures that all FLEXOR® heats meet a high quality vacuum degas electric arc furnace melt process in order to ensure cleanliness, grain refinement and maximum reduction ratios.

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4120 aisi & sae alloy steel

SAE 4120 Steel Chemistry Composition vs. FLEXOR®

Alloys 4120 FLEXOR®
Carbon (C) .18 - .23 .32 - .36
Manganese (Mn) .40 - .60 .60 - .80
Phosphorous (P) .035 (max) .025 (max)
Sulfur (S) .04 (max) .025 (max)
Silicon (Si) .15 - .35 .15 - .30
Chromium (Cr) .80 - 1.10 .75 - 1.00
Molybdenum (Mo) .15 - .25 .40 - .60
Tungsten (W) - .40 - .70

Typical FLEXOR® Mechanical Properties (Based upon 1.00" dia.)

Mechanical Properties UTS (ksi) Per ASTM E8-04 YS 0.2% offset Per ASTM E8-04 V-Notch Charpy Impact Per ASTM E23-06 RA% Per ASTM E8-04 Elongation Per ASTM E8-04 Poisson's Ratio per ASTM E111-04 Young Modulus per ASTM E111
30 HRC 147 147 80 64 21 N/A N/A
40 HRC 183 183 45 60 18 .282 30900 (ksi)
45 HRC 225 225 21 50 12 N/A N/A

Contact Pennsylvania Steel Corporation today to learn more about FLEXOR® and its advantages over 4120 alloy steel. 

FLEXOR® Properties

FLEXOR®'s dependable quality and adaptability in heat treatment allows for a wide range of physical properties that are more appealing than those of typical ASTM, AISI or SAE 4120 alloy steel.

FLEXOR® has a higher core hardness, resulting in a more uniform hardness through any cross section. The more uniform hardness and a fine grain microstructure produce a steel that is low weight with high fatigue and tensile strength and is an excellent material for applications that require a lighter weight component with the strength of steel.

FLEXOR® Sizes & Conditions

FLEXOR® steel is available in a variety of sizes and conditions. These include, but are not limited to:

  • Decarb free alloys
  • Hot rolled rounds
  • Peeled steel bars
  • Ground and polished rounds
  • Hot rolled flats
  • Hot rolled plates
  • Turned forged round and billet

Questions? Ask Our FLEXOR® Experts

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