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    2. B18.3.1M Socket Head Cap Screws

    ASME B18.3.1M Socket Head Cap Screws Dimensions

    Metric socket head cap screws manufactured according to ASME B18.3.1M fastening specifications.

    ASME B18.3.1M Socket Head Cap Screws are widely used in precision machinery, industrial equipment, automotive systems, and engineering assemblies. These metric socket screws provide high-strength fastening, compact head design, and reliable torque transmission for metric industrial fastening applications.

    ASME B18.3.1M Socket Head Cap Screws

    Nom. Sizeand Thread Pitch Body Diameter, D Head Diameter A Head Height H Chamferor Radius S Hexagon Socket Sizea J Spline Socket Sizea M Key Engagement T Transition Dia. B a
    Max Min. Max Min. Max Min. Max Nom. Nom. Min. Max
    ASME B18.3.1M - M1.6 × 0.35 1.6 1.46 3 2.87 1.6 1.52 0.16 1.5 1.829 0.8 2
    ASME B18.3.1M - M2 × 0.4 2 1.86 3.8 3.65 2 1.91 0.2 1.5 1.829 1 2.6
    ASME B18.3.1M - M2.5 × 0.45 2.5 2.36 4.5 4.33 2.5 2.4 0.25 2 2.438 1.25 3.1
    ASME B18.3.1M - M3 × 0.5 3 2.86 5.5 5.32 3 2.89 0.3 2.5 2.819 1.5 3.6
    ASME B18.3.1M - M4 × 0.7 4 3.82 7 6.8 4 3.88 0.4 3 3.378 2 4.7
    ASME B18.3.1M - M5 × 0.8 5 4.82 8.5 8.27 5 4.86 0.5 4 4.648 2.5 5.7
    ASME B18.3.1M - M6 × 1 6 5.82 10 9.74 6 5.85 0.6 5 5.486 3 6.8
    ASME B18.3.1M - M8 × 1.25 8 7.78 13 12.7 8 7.83 0.8 6 7.391 4 9.2
    ASME B18.3.1M - M10 × 1.5 10 9.78 16 15.67 10 9.81 1 8 ... 5 11.2
    ASME B18.3.1M - M12 × 1.75 12 11.73 18 17.63 12 11.79 1.2 10 ... 6 14.2
    ASME B18.3.1M - M14 × 2b 14 13.73 21 20.6 14 13.77 1.4 12 ... 7 16.2
    ASME B18.3.1M - M16 × 2 16 15.73 24 23.58 16 15.76 1.6 14 ... 8 18.2
    ASME B18.3.1M - M20 × 2.5 20 19.67 30 29.53 20 19.73 2 17 ... 10 22.4
    ASME B18.3.1M - M24 × 3 24 23.67 36 35.48 24 23.7 2.4 19 ... 12 26.4
    ASME B18.3.1M - M30 × 3.5 30 29.67 45 44.42 30 29.67 3 22 ... 15 33.4
    ASME B18.3.1M - M36 × 4 36 35.61 54 53.37 36 35.64 3.6 27 ... 18 39.4
    ASME B18.3.1M - M42 × 4.5 42 41.61 63 62.31 42 41.61 4.2 32 ... 21 45.6
    ASME B18.3.1M - M48 × 5 48 47.61 72 71.27 48 47.58 4.8 36 ... 24 52.6
    • a See also Table 25.
    • b The M14 ×2 size is not recommended for use in new designs.
    • All dimensions are in millimeters
    • LG is grip length and LB is body length. For length of complete thread.
    • For additional manufacturing and acceptance specifications, see ASME B18.3.1M-1986.

    Frequently Asked Questions

    What grades of nonferrous metal does ASTM F468 cover for din 912?

    ASTM F468 covers copper (C11000), brass (C26000, C27000, C46200, C46400), bronze (C51000 phosphor, C61300/C61400/C63000 aluminum, C64200, C65100/C65500/C66100 silicon, C67500 manganese), cupro-nickel (C71000, C71500), nickel-base alloys (N04400 Monel 400, N04405, N05500 Monel K-500, N06059 Alloy 59, N06625 Inconel 625, N06686, N10001 Hastelloy B-2, N10276 Hastelloy C-276), aluminum (A92024, A96061, A97075), and titanium (R50250 Gr 1, R50400 Gr 2, R50700 Gr 4, R56400 Gr 5, R56401 Gr 23 ELI, R52400 Gr 7, R58640 Gr 19, R55111 Gr 32) - all available for this product family at TorqBolt.

    What is the dimensional standard for these din 912?

    This product follows ASME B18.3 1M, the dimensional standard for din 912. Material chemistry, mechanical properties, and acceptance criteria follow ASTM F468 / F468M for nonferrous bolting. TorqBolt supplies both inch-series and metric sizes per the applicable ASME or ISO drawing.

    Which F468 grades are best for marine and seawater service?

    For seawater bolting per F468: Monel 400 (N04400) and Monel K-500 (N05500) resist chloride stress-corrosion cracking and HF acid; nickel-aluminum bronze C63000 is the standard high-strength marine fastener; cupro-nickel C71500 is preferred for condenser tube-sheet bolting; naval brass C46400 is the lower-cost option for routine marine hardware; titanium Grade 2 (R50400) is the premium choice for severe chloride + chemical service.

    Are F468 din 912 NACE MR0175 acceptable for sour service?

    Most F468 nickel and titanium grades are NACE MR0175 / ISO 15156-listed: Monel 400 (N04400), Monel K-500 (N05500) conditional, Inconel 625 (N06625), Hastelloy B-2 (N10001), Hastelloy C-276 (N10276), Alloy 59 (N06059), Alloy 686 (N06686), and all titanium grades (R50400, R52400, R56400, R56401). Aluminum bronzes are generally not preferred for sour service. TorqBolt provides NACE-compliant heat-treat and hardness reports on request.

    References & Standards

    • ASTM F468 / F468M - Standard Specification for Nonferrous Bolts, Hex Cap Screws, and Studs for General Use
    • ASTM F467 / F467M - Companion specification for Nonferrous Nuts (mate with F468 for matched-alloy assemblies)
    • ASTM F436 / F436M - Hardened steel washers (ferrous washer companion when nonferrous washers are not specified)
    • NACE MR0175 / ISO 15156 - Sour-service hardness limits for petroleum and natural gas industries
    • ASME B18.2.1 / B18.2.3 series / B18.3 / B18.6.7M / B18.31 / B16.5 - Dimensional standards referenced by F468
    • DIN 912 / 933 / 931 - Metric hex socket head and hex head cap screw dimensional standards
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