ASTM A453/A453M Grade 660 Class C Bolting Specification

High Temperature Precipitation Hardened Stainless Steel Bolting

ASTM A453/A453M Grade 660 Class C Hex Bolts, Push Bolts, Studs, Socket Head Cap Screws, Threaded Rods, Nuts & Washers

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 doubel 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.

ASTM A453/A453M Grade 660 Class C Bolting Types

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

ASTM A453/A453M Grade 660 Class C Chemical requirements

Grade	UNS Number	Elements	C	Mn	P	S	Si	Ni	Cr	Mo	W	Ti	Nb A	Al	V	B	Cu
ASTM A453 Grade 660	S66286	Content, %	0.08 max	2.00 max	0.040 max	0.030 max	1.00 max	24.0-27.0	13.5-16.0	1.00-1.50	...	1.90-2.35	...	0.35 max	0.10-0.50	0.001-0.010	...
		Product Analysis Variation, Over or Under, %	0.01 over	0.04	0.005 over	0.005 over	0.05	0.2	0.2	0.05	...	0.05	...	0.05 over	0.03	0.0004 under to 0.001 over	...
(A) Or columbium plus tantalum.

ASTM A453/A453M Grade 660 Class C Mechanical Properties

Grade	Class	Tensile Strength, min		Yield Strength (0.2 % Offset), min		Elongation in 4× Diam, min, %	Reduction of Area, min, %	Brinell Hardness Number	Approximate Rockwell Hardness, B and C
		ksi	MPa	ksi	MPa				min	max
ASTM A453/A453M Grade 660	C	130	895	85	585	15	18	248-341	24 HRC	37 HRC
(A) Bolting material sizes 3 in. [76 mm] and under in diameter. (B) Bolting material sizes over 3 in. [76 mm] in diameter. (C) Conversion numbers taken from Specification A193/A193M, Table number 2 (austenitic steels); others by interpolation.

ASTM A453/A453M Grade 660 Class C Stress Rupture Properties

Grade	Class	Test Temperature, °F [°C]	Stress, min		Time to Rupture, min, hA	Elongation, min, %
			ksi	MPa
ASTM A453/A453M Grade 660	C	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.

Smooth-Notch Stress-Rupture Test Specimen

Specimen Dimensions	Specimen Type	Mid-length Gage Dia D and Notch-Root Dia F	Gage Length, G	Shoulder Diameter, H	Notch-Root Radius
Inches	1	0.125	0.5	0.177	0.005
	2	0.160	0.65	0.226	0.005
	3	0.178	0.75	0.250	0.005
	4	0.252	1.0	0.375	0.007
	5	0.357	1.5	0.500	0.010
	6	0.505	2.0	0.750	0.015
	Tolerance	±0.001	±0.05	±0.003	±0.0005
Millimetres	7	3.17	12.0	4.5	0.13
	8	4.06	17.0	5.5	0.13
	9	4.52	20.0	6.5	0.13
	10	6.40	25.0	9.5	0.18
	11	9.07	40.0	12.0	0.25
	12	12.8	50.0	19.0	0.38
	Tolerance	±0.025	±1.3	±0.1	±0.01

ASTM A453/A453M Grade 660 Class C 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 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

ASTM A453/A453M Grade 660 Class C Bolting Components Marking

Product Shall be Marked with our manufacturing trade mark "TorqBolt" or "TB" along with the designated Grade.
Grade and manufacturer’s identification symbols shall be applied to one end of studs and to the heads of bolts and screws of all sizes. (If the available area is inadequate, the grade symbol may be marked on one end and the manufacturer’s identification symbol marked on the other end.) For bolts and screws smaller than 1⁄4 in. [6 mm] in diameter and studs smaller than 3⁄8 in. [10 mm] in diameter and for 1⁄4 in. [6 mm] in diameter studs requiring more than a total of three symbols, the marking shall be a matter of agreement between the purchaser and the manufacturer.

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

Threads may be formed by machining or rolling. Threads may be formed after precipitation heat treatment or after solution anneal but prior to precipitation heat treatment. Type designations are as follows:

• Type M1 -Threads formed by machining after precipitation heat treatment.
• Type M2 - Threads formed by machining after solution anneal but prior to precipitation heat treatment.
• Type R1 - Threads formed by rolling after precipitation heat treatment.
• Type R2 - Threads formed by rolling after solution anneal but prior to precipitation heat treatment.

When not specified by the purchaser, the type supplied shall be the option of the manufacturer.

ASME Dimensional Standards

ASTM A453/A453M Grade 660 Class C Permissible Variations in Size of Cold-Finished Bars

Specified Size, in. [mm]	Permissible Variations from Specified Size, in. [mm]A
	Over	Under
Over 1/2 to 1 [13 to 25], excl	0.002  [0.05]	0.002  [0.05]
1 to 11/2 [25 to 38], excl	0.0025 [0.06]	0.0025 [0.06]
11/2 to 4 [38 to 100], inclB	0.003  [0.08]	0.003  [0.08]
(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.