Tool knowledge

    What Does S2 Mean on Tools' Steel Bits?

    10-Dec
    What Does S2 Mean on Tools' Steel Bits?
    S2 alloy steel is a shock-resisting tool steel type. It retains good ductility even in hardened conditions, which allows it to perform in applications where shock impact is transmitted to the alloy. Shock-resisting tool steels like this are designated as group S steels.Chemical CompositionThe follow

    S2 alloy steel is a shock-resisting tool steel type. It retains good ductility even in hardened conditions, which allows it to perform in applications where shock impact is transmitted to the alloy. Shock-resisting tool steels like this are designated as group S steels.

    Chemical Composition

    The following table shows the chemical composition of S2 tool steels.

    ElementContent (%)
    Iron, Fe97.0
    Silicon1.05
    Carbon, C0.4-0.55
    Molybdenum, Mo0.4
    Manganese, Mn0.4
    Vanadium, V≤0.5
    Phosphorus, P≤0.03
    Sulfur, S≤0.03

    How strong is S2 alloy steel?

    Physical PropertiesMetricEnglishComments
    Density7.83g/cc0.283lb/in³




    Mechanical PropertiesMetricEnglishComments
    Hardness, Knoop624624Converted from Rockwell C Hardness.
    Hardness, Rockwell C5555
    Hardness, Vickers602602Converted from Rockwell C Hardness.
    Tensile Strength, Ultimate2150MPa312000psi
    Tensile Strength, Yield2000MPa290000psi
    Elongation at Break7.0 %7.0 %in 50 mm
    Bulk Modulus160GPa23200ksiTypical for steel
    Shear Modulus80.0GPa11600ksiTypical for steel




    Thermal PropertiesMetricEnglishComments
    CTE, linear10.9µm/m-°C
    @Temperature 20.0 - 100 °C
    6.06µin/in-°F
    @Temperature 68.0 - 212 °F


    13.0µm/m-°C
    @Temperature 0.000 - 300 °C
    7.22µin/in-°F
    @Temperature 32.0 - 572 °F


    14.1µm/m-°C
    @Temperature 0.000 - 500 °C
    7.83µin/in-°F
    @Temperature 32.0 - 932 °F





    Processing PropertiesMetricEnglishComments
    Processing Temperature175- 425°C347- 797°FTempering Temperature

    845- 900°C1550- 1650°FHardening Temperature
    Annealing Temperature760- 790°C1400- 1450°F




    Component Elements PropertiesMetricEnglishComments
    Carbon, C0.40 - 0.55 %0.40 - 0.55 %
    Iron, Fe97 %97 %As Balance
    Manganese, Mn0.40 %0.40 %
    Molybdenum, Mo0.40 %0.40 %
    Phosphorus, P<= 0.030 %<= 0.030 %
    Silicon, Si1.05 %1.05 %
    Sulfur, S<= 0.030 %<= 0.030 %
    Vanadium, V<= 0.50 %<= 0.50 %

    Physical Properties

    The physical properties of S2 tool steels are given in the following table.

    PropertiesMetricImperial

    Density

    7.79 g/cc

    0.281 lb/in3

    Melting point

    1421°C

    2590°F

    Mechanical Properties

    The mechanical properties of S2 tool steels are tabulated below.

    Properties

    Conditions



    T (°C)

    Treatment



    Poisson's ratio

    0.27-0.30

    25

    -

    Elastic modulus

    190-210 GPa

    25

    -

    Thermal Properties

    The following table shows the thermal properties of S2 tool steels.

    Properties

    Conditions



    T (°C)

    Treatment



    Thermal expansion

    10.9 x 10-6/ºC

    20-100

    -

    Other Designations

    Other designations that are equivalent to S2 tool steels include:

    • ASTM A681

    • FED QQ-T-570

    • SAE J437

    • SAE J438

    • UNS T41902

    Fabrication and Heat Treatment

    Machinability

    The machinability rating of S2 tool steels is 85% of that of the W group steels.

    Forming

    S2 tool steels are formed using conventional procedures under annealed conditions.

    Welding

    S2 tool steels are readily weldable using standard methods.

    Heat Treatment

    S2 tool steels are slowly preheated to 649ºC (1200ºF) and then directly heated by increasing the temperature to 871ºC (1600ºF). This is followed by holding the steels for 10 to 20 mins and quenching in brine or water.

    Forging

    Forging is carried out in S2 tool steels at temperatures ranging from 899 to 1093ºC (1650 to 2000ºF). Forging below 871ºC (1600ºF) is not preferred.

    Cold Working

    S2 tool steels can be cold-worked under annealed conditions.

    Annealing

    Annealing is performed on S2 tool steels at 788ºC (1450ºF) followed by cooling in the furnace at a rate of not more than 4ºC per hour.

    Tempering

    S2 tool steels are tempered at 177 to 427ºC (350 to 800ºF) to obtain Rockwell C hardness of 60 to 50.

    Related Issues

    How strong is S2 alloy steel? Applications for shock-resisting steels include springs, as well as chisels, dies for forging, and punches. S2 steel is also used to make Ball bearings for the mining industry. They are also used for screwdrivers and driver bits.

    What is S2 tool steel used for?

    【DURABLE S2 Material】: The bit socket head is made of S2 alloy steel, which is strong and has good toughness, not easy to break. It is the best material for making a bit set.

    Is S2 steel hardened?

    AISI Type S2 is a water-hardening tool steel with extreme toughness and resistance to shock loading. Even at a hardness of Rockwell C 59-60, it will bend before it breaks.



    If you are looking for a professional screwdriver manufacturerto customize your precision screwdriver set, feel free to contact us today! We provide high-quality, customizable toolsfor various repair needs.