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  • Strain Hardened Fasteners

    • Strain Hardened Stainless Steel Fasteners

    Fasteners, Stud Bolts, Threaded Rod, Nuts, Bolting

    Strain hardened Bolting such as stainless steel threaded rod & stud bolts are made by a cold drawing process that reduces the oversized wires or bars to the desired size. The stainless material with a larger diameter than the one desired for the finished product is drawn down through a compression system. The system puts the material under a greater tension and pressure; this strain reduces the diameter while at the same time increasing the strength of the material.
    As the metal is plastically deformed, the dislocations move as more are created, and more dislocations within the metal mean more interactions, tangling or pinning of the dislocations. The process leads to a decrease in the mobility of the dislocations and subsequent strengthening of the stainless steel material.
    The austenitic stainless steel work hardens at a rapid rate as compared to the Ferritic, Martensitic stainless steel types that have limited strain hardening capabilities. The high ductility of austenitic stainless steels allows them to be heavily cold formed into deep drawn products with high strength levels and useful levels of toughness and ductility.

    Strain Hardened Bolting Materials

    Austenitic Stainless Steel High temperature service

    ASTM A193 Strain Hardened Bolting

    Grade Diameter, Diameter Heat Treatment B Tensile Strength, Yield Strength, min, Tensile Strength, Yield Strength, min, Elongation in 4 D,min % Reduction of Area, min % Hardness,
    in. min, ksi 0.2 % offset, ks min,MPa 0.2 % offset, MPa max
    ASTM A193 Grade B8, B8C, B8P, B8T, B8N D  Class 2 3 / 4  and under M20 and under carbide solution treated and strain hardened 125 100 860 690 12 35 321 HBW or 35 HRC
    over  3 / 4  to 1, incl over M20 to M24, incl 115 80 795 550 15 35 321 HBW or 35 HRC
    over 1 to 1 1 / 4  , incl over M24 to M30, incl 105 65 725 450 20 35 321 HBW or 35 HRC
    over 1 1 / 4  to 1 1 / 2  , incl over M30 to M36, incl 100 50 690 345 28 45 321 HBW or 35 HRC
    ASTM A193 Grade B8M, B8MN, B8MLCuN D  Class 2 3 / 4  and under M20 and under carbide solution treated and strain hardened 110 95 760 655 15 45 321 HBW or 35 HRC
    over  3 / 4  to 1 incl over M20 to M24, incl 100 80 690 550 20 45 321 HBW or 35 HRC
    Over 1 to 1 1 / 4  , incl over M24 to M30, incl 95 65 655 450 25 45 321 HBW or 35 HRC
    over 1 1 / 4  to 1 1 / 2  , incl over M30 to M36, incl 90 50 620 345 30 45 321 HBW or 35 HRC
    ASTM A193 Grade B8, B8M2 D  Class 2B 2 and under M48 and under carbide solution treated and strain hardened 95 75 655 515 25 40 321 HBW or 35 HRC
    over 2 to 2 1 / 2  incl over M48 to M64, incl 90 65 620 450 30 40 321 HBW or 35 HRC
    over 2 1 / 2  to 3 incl over M64 to M72, incl 80 55 550 380 30 40 321 HBW or 35 HRC
    ASTM A193 Grade B8M3 D Class 2C 2 and under M48 and under carbide solution treated and strain hardened 85 65 585 450 30 60 321 HBW or 35 HRC
    over 2 over M48 85 60 585 415 30 60 321 HBW or 35 HRC

    ASTM A320 Strain Hardened Fasteners

    Grade and Class Diameter, in. [mm] Heat Treatment Minimum Tempering Temperature, °F [°C] Tensile Strength, min, ksi [MPa] Yield Strength, min, ksi [MPa] (0.2 % offset) Elongation in 2 in. or 50 mm, min, % Reduction of Area, min, % Hardness, max
    ASTM A320 B8, B8C, B8P, B8F, B8T : Class 2 3/4 [20] and under carbide solution treated and strain  hardened ... 125 [860] 100 [690] 12 35 321 HBW or 35  HRC
    over 3/4 to 1 [20 to 25], incl ... 115 [795] 80 [550] 15 30 321 HBW or 35  HRC
    over 1 to 11/4 [25 to 32], incl ... 105 [725] 65 [450] 20 35 321 HBW or 35  HRC
    over 11/4 to 11/2 [32 to 40], inclA ... 100 [690] 50 [345] 28 45 321 HBW or 35  HRC
    ASTM A320 B8M : Class 2 3/4 [20] and under carbide solution treated and strain  hardened ... 110 [760] 95 [655] 15 45 321 HBW or 35  HRC
    over 3/4 to 1 [20 to 25], incl ... 100 [690] 80 [550] 20 45 321 HBW or 35  HRC
    over 1 to 11/4 [25 to 32], incl ... 95 [655] 65 [450] 25 45 321 HBW or 35  HRC
    over 11/4 to 11/2 [32 to 40], inclA ... 90 [620] 50 [345] 30 45 321 HBW or 35  HRC

    ASTM F593 Strain Hardened Bolting

    Stainless Alloy Group ConditionB Alloy Mechanical Property Marking Nominal Diameter, in. Full-Size Tests Machined Specimen Tests
    Tensile Strength ksiC Yield Strength, ksiD,C Rockwell Hardness Tensile Strength ksiC Yield Strength, ksiD,C Elongation in 4 D, %
    1 (303, 304,304 L, 305,384,XM1,
    18-9LW, 302HQ, 304J3, 303Se)     		SH1 F593A 1/4 to 5/8 , incl 120 to 160 95 C24 to C36 115 90 12
    SH2 F593B 3/4 to 1, incl 110 to 150 75 C20 to C32 105 70 15
    SH3 F593C 11/8 to 11/4 , incl 100 to 140 60 B95 to C30 95 55 20
    SH4 F593D 13/8 to 11/2 , incl 95 to 130 45 B90 to C28 90 40 28
    2 (316,316L) SH1 F593E 1/4 to 5/8 , incl 120 to 160 95 C24 to C36 115 90 12
    SH2 F593F 3/4 to 1, incl 110 to 150 75 C20 to C32 105 70 15
    SH3 F593G 11/8 to 11/4 , incl 100 to 140 60 B95 to C30 95 55 20
    SH4 F593H 13/8 to 11/2 , incl 95 to 130 45 B90 to C28 90 40 28
    3 (321, 347) SH1 F593J 1/4 to 5/8 , incl 120 to 160 95 C24 to C36 115 90 12
    SH2 F593K 3/4 to 1, incl 110 to 150 75 C20 to C32 105 70 15
    SH3 F593L 11/8 to 11/4 , incl 100 to 140 60 B95 to C30 95 55 20
    SH4 F593M 13/8 to 11/2 , incl 95 to 130 45 B90 to C28 90 40 28

    Strain hardened fasteners benefits

    The benefit of strain hardened stainless steel fasteners is a combination of high strength and equivalent corrosion resistance. The chemical composition of Strain hardened Bolting is same as that non-strain-hardened bolting. Ideally Strain hardened stainless Steel fasteners bear the same tensile & yield strength as compared to that of ISO 898-1 Class 8.8 / ASTM A193 B7 / ASTM A320 L7 / SAE J429 Grade 5 Bolting.
    Comparison of mechanical properties of heat treated fasteners with strain hardened fasteners