ASTM A638 Bolts

ASTM A638 is the Standard Specification for Precipitation Hardening Iron Base Superalloy Bars, Forgings, and Forging Stock for High-Temperature Service. This specification covers alloys with mechanical properties developed by suitable solution treating and precipitation hardening treatments.Based on design, service conditions, mechanical properties, and elevated temperature characteristics ASTM A638 covers two grades of iron based alloys.

ASTM A638 Bars, Forgings, Forging Stock Manufacturers & Suppliers

Products manufactured under ASTM A638 specification are furnished in three different conditions viz Hot Finished, Solution Annealed, Solution Annealed and precipitation treated.In addition to the requirements of this specification, all requirement of ASTM A 484/A 484M (Specification for General Requirements for Stainless Steel Bars, Billets, and Forgings) Shall Apply.

This Specification Covers three types viz Grade 660 Type 1, Grade 660 Type 2 and Grade 660.

Testing Requirements

Chemical Composition

ASTM A638 Chemical Composition

Grade 660 (UNS S66286)’1 Grade 662 (UNS S66220)’1
Ladle Analysis Range, % Check Analysis Over or Under Ladle Analysis Range, % Check Analysis Over or Under
Carbon 0.08 max 0.01 over 0.08 max 0.01 over
Manganese 2.00 max 0.04 over 1.50 max 0.04
Silicon 1.00 max 0.05 over 1.00 max 0.05
Phosphorus 0.040 max 0.005 over 0.040 max 0.005 over
Sulfur 0.030 max 0.005 over 0.030 max 0.005 over
Chromium 13.50-16.00 0.20 12.00-15.00 0.15
Nickel 24.00-27.00 0.20 24.00-28.00 0.20
Molybdenum 1.00-1.50 0.05 2.50-3.50 0.10
Titanium 1.90-2.35 0.05 1.55-2.00 0.05
Copper  —  — 0.50 max 0.03 over
Aluminum 0.35 max 0.05 over 0.35 max 0.05 over
Vanadium 0.10-0.50 0.03  —  —
Boron 0.0010-0.010 0.0004 under 0.001 over 0.0010-0.010 0.0004 under 0.001 over

A New designation established in accordance with Practice E 527 and SAE J1086.

Mechanical Properties

ASTM A638 Mechanical Properties

Grade 660 Grade 662 (bars) Grade 662 (forgings)-4
Heat treatment® solution + precipitation harden solution + precipitation harden solution + precipitation harden
Tensile strength, min:
psi 130 000 130 000 125 000
[MPa] [8951 C895] [860]
Yield strength CO.2% offset), min: psi 85 000 85 000 80 000
[MPa] [5851 [585] [550]
Elongation in 4D min, % 15 15 15
Reduction of area min, % 18 18 18
Brinell hardness 248 min 248 min 248 min
AThe elongation of tensile specimens machined tangentially from near the center of large disk forgings over 50 in.2 [320 cm2] in cross section may be as low as 10%. The reduction of area may be as low as 12%.B Refer to Table 3 of heat treatment.

Stress-Rupture Requirements

ASTM A638 Stress-Rupture Requirements

Test Temperature Stress Minimum
Grade Heat Treatment-4 °F [°C] psi [MPa] MinimumHours® Elongation,%
660 solution + precipitation harden 1200 [650] 65 000 [450] 23 3
662 solution + precipitation harden 1200 [650] 60 000 [4151 15 3

A Refer to Table 2 for details of heat treatment.

fiTest specimens meeting minimum requirements may be overloaded to produce rupture in a reasonable and practical time period.

Heat Treatment

ASTM A638 Heat Treatment

Grade Solution Treatment Precipitation Hardening Treatment”4
660 Type 1 1650 ± 25°F 900 ± 15°C], hold 2 h, oil or water quench 1300 to 1400°F [705 to 760oC], hold 16 h, air cool or furnace cool
660 Type2 1800 ± 25°F 980 ± 15°C], hold 1 h, oil or water quench 1300 to 1400°F [705 to 760°C], hold 16 h, air cool or furnace cool
662 1750 to 1900°F 955 to 1040°C], hold 1 h, min, oil or water quench 1250 to 1400°F [675 to 760°C1, hold 5 h, min, slow cooling in 5 h, min to 1200 ± 15°F [650 ± 10°C1, hold 20 h, min, air cool or furnace cool

A Times refer to the minimum time material is required to be at temperature.

Download PDF: ASTM A638 at ASTM.org

Related ASTM Specification

ASTM A1082 / A1082M – 16 : Standard Specification for High Strength Precipitation Hardening and Duplex Stainless Steel Bolting for Special Purpose Applications

ASTM A1014 / A1014M – 16 : Standard Specification for Precipitation-Hardening Bolting (UNS N07718) for High Temperature Service

ASTM F2281 : Standard Specification for Stainless Steel and Nickel Alloy Bolts, Hex Cap Screws, and Studs, for Heat Resistance and High Temperature Applications Designation

ASTM A453 / A453M – 16 : Standard Specification for High-Temperature Bolting, with Expansion Coefficients Comparable to Austenitic Stainless Steels

ASTM B637 – 15 : Standard Specification for Precipitation-Hardening and Cold Worked Nickel Alloy Bars, Forgings, and Forging Stock for Moderate or High Temperature Service

ASTM B564 – 15 : Standard Specification for Nickel Alloy Forgings

ASTM A962 / A962M – 16a : Standard Specification for Common Requirements for Bolting Intended for Use at Any Temperature from Cryogenic to the Creep Range

ASTM F467 – 15 : Standard Specification for Nonferrous Nuts for General Use

ASTM F468 – 15 : Standard Specification for Nonferrous Bolts, Hex Cap Screws, Socket Head Cap Screws, and Studs for General Use

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