Machining DataSheet for

General Information:
Material GroupP - Steel
Sub-GroupLow Alloy Steel
Tensile Strength740-1080 [N/mm^2]
Machinability61%

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Machining Steel 4140

SAE 4140 is Chromium-molybdenum steel produced with 0.15–0.25% of molybdenum, and 0.80–1.10% of chromium content. It has high hardenability; good fatigue, abrasion, and impact resistance; and can be nitrided for maximum wear and abrasion resistance. 4140 Steel is used where fatigue, abrasion, and impact resistance are needed. 4140 steel is used for high-strength machine parts such as connecting rods, crankshafts, steering knuckles, axles, pump parts, gears, and pinions. It is also used in the production of cutting tools.

The hardness of these steels depends on the heat treatment:

  • 195 HB - Anealed.
  • 240–300 HB - Normalized.
  • 230–340 HB - Quenched

The average machinability rating of 4140 steel is 70% (Annealed condition)

You can find here a list of machinability Ratings for different Low Alloy Steels.

Summery:

  • For turning operations on Steel 4140, it is best to use inserts with thick CVD coating and medium hardness. For milling, any all-around carbide grade is suitable.
  • For detailed carbide grades recommendations, check the Below Chart, or use the Grades Wizrad.
  • Recommended Cutting speed range for turning at stable conditions is 740 - 1000 [SFM] / 225 - 305 [m/min].
  • Recommended Cutting speed range for milling with stable clamping and short overhang is 460 - 620 [SFM] / 140 - 190 [m/min]
  • For detailed cutting speed recomendations, check the Below Table, or use our Speed and Feed Calculator.

    • Equivalent International Designations for Steel 4140

    Standard Name
    sae4140
    wnr1.7225
    din42CrMo4
    bs708M40
    ss2244
    anfor42CD4
    uni42CrMo4
    unf42CrMo4
    js1SCM440(H)

    Chemical Composition for Steel 4140

    Element Amount
    Chromium (Cr).80-1.10%
    Manganese (Mn).75-1.00%
    Carbon (C).38-.43%
    Molybdenum (Mo).15-.25%

    Cutting Speeds Recomendations for Steel 4140

    * Click on the speeds below for higher precision in specific conditions!

    ApplicationVc (m/min)Vc (SFM)
    Turning225-305740-1000
    Milling140-190460-620
    Parting105-145340-480
    Grooving125-170410-560
    Drilling90-120300-390

    Important! The speed estimation is given for an ideal situation:

    • Most suitable carbide grade
    • Stable tool clamping
    • Stable workpiece clamping
    • Good quality raw material
    • A short overhang of the cutting tool.
    • Nominal hardness of the material.
    • etc.
    Click on the speeds in the above table to get better precision for specific parameters
    Or use our Speed and Feed Calculator


    Recommended Carbide Grades for Steel 4140

    * If you do nott understand the below table? Read This Explanation to make the most out of it!

    Grade for Turning

    Grade for Parting Off

    Grade for Grooving

    Grade for Milling (Indexable)

    Recommended Insert Cutting Edge Geometry for Steel 4140

    Honing Size:0.05-0.08 mm / 0.002-0.003"
    Rake Angle:11° -13°
    Land Angle:Positive
    Land Width:0.20-0.30 mm / 0.008-0.012"

    Learn more about carbide inserts Cutting-Edge Geometry Parameters.

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