ASTM A278/A278M-01(2006)

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Designation:A278/A278M–01 Designation: A 278/A 278M – 01 (Reapproved 2006)
Standard Specification for
Gray Iron Castings for Pressure-Containing Parts for
Temperatures Up to 650°F (350°C)
This standard is issued under the fixed designationA 278/A 278M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope
1.1 This specification covers gray iron for castings suitable for pressure-containing parts for use at temperatures up to 650°F
(350°C).
1.2 Classes of Iron:
1.2.1 Castings of all classes are suitable for use up to 450°F (230°C). For temperatures above 450°F and up to 650°F, only Class
40, 45, 50, 55, and 60 castings are suitable.
1.2.2 Castings of all classes are suitable for use up to 230°C. For temperatures above 230°C and up to 350°C, only Class 275,
300, 325, 350, 380, and 415 castings are suitable.
2. Referenced Documents
2.1 ASTM Standards:
A 644 Terminology Relating to Iron Castings
E 8 Test Methods for Tension Testing of Metallic Materials
3. Terminology
3.1 Definitions of many terms common to gray iron castings may be found in Terminology A 644.
4. Classification
4.1 Classification by tensile strength.
4.1.1 Castings ordered to this specification are classified based upon the minimum tensile strength of the iron in ksi, in English
units. Class 25 has a minimum specified tensile strength of 25 ksi.
4.1.2 Castings ordered to this specification are classified based upon the minimum tensile strength of the iron in MPa, in Metric
units. Class 150 has a minimum specified tensile strength of 150 MPa.
5. Ordering Information
5.1 Orders for material in this specification should include the following information:
5.1.1 ASTM designation and year date,
5.1.2 Class of iron required and service temperature,
5.1.3 Quantity,
5.1.4 Heat Treatment:
5.1.4.1 Whether or not heat treatment is required for Class 40, 45, 50, 55, and 60 castings to be used at temperatures at 450°F
or less (see 6.2),
5.1.4.2 Whether or not heat treatment is required for Class 275, 300, 325, 350, 380, and 415 castings to be used at temperatures
at 230°C or less (see 6.2),
5.1.5 The size of separately cast test bar to be poured (see Section 9 and Table 1),
5.1.6 The size of test specimen to be machined from test bars C or S, and
This specification is under the jurisdiction of ASTM Committee A04 on Iron Castings and is the direct responsibility of Subcommittee A04.01 on GrayGrey and White
Iron Castings.
Current edition approved June 10, 2001.Oct. 1, 2006. Published September 2001.October 2006. Originally published asA278–44T.approved in 1944. Last previous edition
A278–93.approved in 2001 as A 278/A 278M – 01.
For ASME Boiler and Pressure Vessel Code applications see related Specification SA-278 in Section II of that Code.
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book ofASTM Standards
, Vol 01.02.volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
A 278/A 278M – 01 (2006)
TABLE 1 Diameters and Lengths of Cast Test Bars
Test As-Cast Diameter, in. (mm) Length, in. (mm)
Bar
Minimum Maximum Minimum Maximum
(Bottom) (Top) (Specified) (Recommended)
A 0.88 (23) 0.85 (22) 0.96 (25) 5.0 (125) 6.0 (1.50)
B 1.20 (33) 1.14 (32) 1.32 (36) 7.0 (150) 9.0 (230)
C 2.00 (54) 1.90 (53) 2.10 (58) 6.0 (175) 10.0 (255)
A
S
A
AlldimensionsofTestBarSshallbeagreeduponbythemanufacturerandthe
purchaser.
5.1.7 Special requirements.
6. Materials and Manufacture
6.1 Castingsintendedforuseabove450°F(230°C)shallbestress-relievedbyplacingtheminasuitablefurnaceatatemperature
not exceeding 400°F (200°C) and heating them uniformly to the temperatures and for the times specified in Table 2. The heating
and cooling rates shall be uniform and shall not be more than 400°F/h (250°C/h) for castings of 1-in. (25-mm) maximum section.
For heavier sections the maximum heating and cooling rates in degrees Fahrenheit per hour shall be 400 divided by the maximum
section thickness.
6.2 Heat Treatment and Cooling Rate:
6.2.1 Castings of Class Nos. 45, 50, 55, and 60, which are to be used at temperatures below 450°F, may be heat treated in
accordance with 6.1 or they shall be cooled in the mold to 500°F at an average rate of not more than 100°F/h for castings up to
1 in. in section. For heavier sections the maximum cooling rate in degrees Fahrenheit per hour shall be 100 divided by the
maximum section thickness.
6.2.2 Castings of Class Nos. 275, 300, 325, 350, 380, and 415, which are to be used at temperatures below 230°C, may be heat
treated in accordance with 6.1 or they shall be cooled in the mold to 250°C at an average rate of not more than 50°C/h for castings
up to 25-mm in section. For heavier sections the maximum cooling rate in degrees Celsius per hour shall be 1250 divided by the
maximum section thickness.
7. Chemical Composition
7.1 Carbon Equivalent:
7.1.1 Class 40, 45, 50, 55, and 60 castings intended for service above 450°F (230°C) shall have a maximum carbon equivalent
of 3.8 % as calculated from the equation CE = %C + 0.3 (%Si + %P). The maximum phosphorus and sulfur contents shall be
0.25 % and 0.12 %, respectively.
7.1.2 Class 275, 300, 325, 350, 380, and 415 castings intended for service above 230°C shall have a maximum carbon
equivalent of 3.8 % as calculated from the equation CE = %C + 0.3 (%Si + %P). The maximum phosphorus and sulfur contents
shall be 0.25 % and 0.12 %, respectively.
7.2 The chemical analysis for total carbon shall be made on either chilled cast pencil-type specimens or thin wafers
approximately ⁄32 in. thick cut from test coupons. Drillings shall not be used because of attendant loss of graphite.
8. Tensile Requirements
8.1 IronusedinsupplyingcastingstothisspecificationshallconformtothetensilerequirementsprescribedinTable3andTable
4.
9. Test Bars
9.1 Separately cast test bars having the dimensions shown in Table 1 shall be poured from the same lot as the castings
represented. The size of the test bar to be poured shall be selected by the purchaser using Table 5. In the event no choice is made,
the selection will be made by the manufacturer.
9.2 Separately cast test bars shall be heat treated in the same furnace together with the castings represented.
TABLE 2 Stress Relieving Requirements
A
Class Metal Temperature, °F Holding Time, h
(°C)
40, 45, 50, 55, 60 1050 to 1200 2 12
B B
(275, 300, 325, 350, (565 to 650) (2 min) (12 max)
380, 415)
A
In no case shall the holding time be less than 1 h/in. of maximum metal
section, or in excess of 12 h max, dependent upon which governs.
B
In no case shall the holding time be less than1hfor every 25-mm metal
section, or in excess of 12 h max, depending upon which governs.
A 278/A 278M – 01 (2006)
TABLE 3 Tensile Requirements
Class Tensile Strength,
min, ksi
No. 20 20
No. 25 25
No. 30 30
No. 35 35
No. 40 40
No. 45 45
No. 50 50
No. 55 55
No. 60 60
TABLE 4 Tensile Requirements (SI)
Class Tensile Strength,
min, MPa
No. 150 150
No. 175 175
No. 200 200
...