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    2. ASTM A453 Grade 660 Class C Specification

    ASTM A453 Grade 660 Class C Specification

    ASTM A453 Grade 660 Class C specification provides a yield strength viz. 85 ksi [585 MPa] respectively for use in high temperature service for bolting components such as Stud bolts, screws, nuts, hex bolts & various other fasteners for pressure vessel and valve flanges. A453 Grade 660 Class C is oil quenched and double age hardened to achieve superior grain structure as compared to Class A,B & D . ASTM A453 Grade 660 Class C is produced in various other forms like wire rods, round bars, shafts, castings, forgings, threaded bars, threaded rods, wires, tubings, sheets, plates, welding rods, hex bars, Rivets & Springs. A453 Gr. 660 Cl. C Fasteners are stress rupture tested for 100 Hours at 650°C in finished condition. ASTM A453 Grade 660 Class C Bolting can be certified under nace provided the hardness is controlled and not over 35HRC.

    Table Of Contents

    ASTM A453 Grade 660 Class C Properties

    Chemical Composition

    Grade ASTM A453 Grade 660 Class C
    UNS Number S66286
    Elements Content, % Product Analysis Variation,
    Over or Under, %
    Carbon (C) 0.08 max 0.01 over
    Manganese (Mn) 2.00 max 0.04
    Phosphorus (P) 0.040 max 0.005 over
    Sulfur (S) 0.030 max 0.005 over
    Silicon (Si) 1.00 max 0.05
    Nickel (Ni) 24.0-27.0 0.2
    Chromium (Cr) 13.5-16.0 0.2
    Molybdenum (Mo) 1.00-1.50 0.05
    Titanium (Ti) 1.90-2.35 0.05
    Aluminum (Al) 0.35 max 0.05 over
    Vanadium (V) 0.10-0.50 0.03
    Boron (B) 0.001-0.010 0.0004 under
    to
    0.001 over

    Mechanical Properties

    Grade ASTM A453/A453M Grade 660
    Class C
    Tensile Strength, min ksi 130
    MPa 895
    Yield Strength (0.2 % Offset), min ksi 85
    MPa 585 
    Elongation in 4× Diam, min, % 15
    Reduction of Area, min, % 18
    Brinell Hardness Number 248-341
    Approximate Rockwell Hardness, B and C min 24 HRC
    max 37 HRC

    Stress Rupture Test

    ASTM A453 Grade 660 Class B Stress Rupture
    Grade Class Test Temperature, °F [°C] Stress, min Time to Rupture, min, hA Elongation, min, %
    ksi MPa
    ASTM A453/A453M Grade 660 B 1200 [650] 56 385 100 5
    • (A) The combination bar specimen shown in Fig. 1 shall be tested continuously at the temperature and at the minimum stress specified or at a greater stress and shall rupture in a time not less than that specified.
    • (A) When it is necessary to heat treat or heat treat and pickle after cold finishing, because of special hardness or mechanical property requirements, the permissible variations are generally double those shown in the table.
    • (B) For size tolerances of sizes over 4 in. [100 mm], the manufacturer should be consulted.

    Heat Treatment

    Annealing & Ageing Cycles

    Grade Symbol Class Solution Treatment Hardening Treatment
    ASTM A453/A453M Grade 660 C 1800 ± 25 °F [980 ± 14 °C], hold 1 h min, and oil quench 1425 ± 25 °F [775 ± 14 °C] hold 16 h, air cool, followed by 1200 ± 25 °F [650 ± 14 °C] hold 16 h, air cool  
    • (A) Times refer to the minimum time material is required to be at temperature.

    Continuous Heat Treatment Charge Sizes

    Diameter, in. [mm] Weight, lb [kg]
    To 13/4 [44] 3000 [1400]
    Over 13/4 [44] to 21/2 [63] 6000 [2700]
    Over 21/2 [63] 12000 [5400]

    Lot / Batch Sizes

    Diameter, in. [mm] Maximum Lot Size, lb [kg]
    11/2 [38] and under 200 [90]
    Over 11/2 [38] to 13/4 [44], incl 300 [140]
    Over 13/4 [44] to 21/2 [63], incl 600 [270]
    Over 21/2 [63] 20 pieces

    Marking Requirements

    Grade Marking
    ASTM A453/A453M GRADE 660 CLASS C TB 660C M1/M2/R1/R2

    Bolting Threading Types

    Specification Grade UNS No. CLASS Type
    ASTM A453/A453M Grade 660 S66286 Class C M1 M2 R1 R2

    ASTM A453 Grade 660 Class C Product Range

    Based on the application & Usage

    ASTM A453 Grade 660 Bars / Rods

    Bars / Rods

    ASTM A453 Grade 660 Forgings

    Forgings

    ASTM A453 Grade 660 Heavy Hex Nuts

    Heavy Hex Nuts

    ASTM A453 Grade 660 Bolts

    Bolts

    ASTM A453 Grade 660 Hex Bolts

    Hex Bolts

    ASTM A453 Grade 660 Socket Head Cap Screws

    Socket Head Cap Screws

    ASTM A453 Grade 660 Push Bolts / Rods

    Push Bolts / Rods

    ASTM A453 Grade 660 Hex Cap Screws

    Hex Cap Screws

    ASTM A453 Grade 660 Set Screws / Grub Screws

    Set Screws / Grub Screws

    ASTM A453 Grade 660 Washers

    Washers

    ASTM A453 Grade 660 Countersunk Screws

    Countersunk Screws

    ASTM A453 Grade 660 U Bolt

    U Bolt

    ASTM A453 Grade 660 Stud Bolt

    Stud Bolts

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    • Specifications
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