ASTM A434/A434M-18

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Designation: A434/A434M − 17 A434/A434M − 18
Standard Specification for
Steel Bars, Alloy, Hot-Wrought or Cold-Finished, Quenched
and Tempered
This standard is issued under the fixed designation A434/A434M; 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 U.S. Department of Defense.
1. Scope*
1.1 This specification covers hot-wrought and cold-finished quenched and tempered alloy steel bars.
1.2 Hot-wrought bars are available in three strength level classes designated BB, BC, and BD, and cold-finished bars in two
strength level classes designated BB and BC. The bars are available in the conditions specified in 4.4 subject to the size limitations
shown.
1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
A29/A29M Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought
A108 Specification for Steel Bar, Carbon and Alloy, Cold-Finished
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
E112 Test Methods for Determining Average Grain Size
3. Ordering Information
3.1 Orders for material under this specification should include the following information:
3.1.1 Quantity (weight or number of pieces),
3.1.2 Name of material (heat-treated alloy steel bars),
3.1.3 Method of finish (condition) (4.4),
3.1.4 Dimensions, including length (if hot-wrought bars are for cold finishing, the cold-finished size should also be specified),
3.1.5 ASTM designation and date of issue,
3.1.6 Chemical composition grade (Section 5),
3.1.7 Strength class (Table 1),
3.1.8 Test report, if required (Section 11),
3.1.9 Supplementary Requirements or Special Require-
ments, if required, and
3.1.10 End use.
NOTE 1—A typical ordering description is as follows: 10 000 lb, Heat-Treated Alloy Steel Bars, Hot Rolled, 1.000 in. diameter × 10 ft, ASTM A434
dated ____, Grade 4140, Class BB, Test Report Required, Motor Shafts.
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.15
on Bars.
Current edition approved March 15, 2017July 1, 2018. Published March 2017July 2018. Originally approved in 1959. Last previous edition approved in 20152017 as
A434/A434M – 15.A434/A434M–17. DOI: 10.1520/A0434_A0434M-17.10.1520/A0434_A0434M–18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
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A434/A434M − 18
TABLE 1 Tensile Properties
NOTE 1—The mechanical properties of hot-wrought bars ordered for cold finishing, shall be governed by the cold-finished size.
Elongation in Reduction SAE or AISI
Yield Strength, min, Tensile Strength,
Class Diameter, in. [mm] 2 in. or 50 of Area, Representative
A
ksi [MPa] min, ksi [MPa]
B
mm, min, % min, % Grade Types
1 ⁄2 [38.1] and under 90 [620] 110 [760] 20 50 3100, 4100,
1 1
Over 1 ⁄2 to 2 ⁄2 [38.1 to 63.5], incl 80 [550] 105 [720] 20 50 8600, 8700
C
BB Over 2 ⁄2 to 4 [63.5 to 102], incl 75 [520] 100 [690] 20 50
Over 4 to 7 [102 to 178], incl 75 [520] 95 [660] 20 50
Over 7 to 10 [178 to 254], incl 65 [450] 90 [620] 18 40
1 ⁄2 [38.1] and under 110 [760] 130 [900] 16 50 3100, 4100, 6100,
1 1
Over 1 ⁄2 to 2 ⁄2 [38.1 to 63.5], incl 105 [720] 125 [860] 16 50 8600, 8700
J
C
BC Over 2 ⁄2 to 4 [63.5 to 102], incl 95 [660] 115 [790] 16 45
Over 4 to 7 [102 to 178], incl 85 [590] 110 [760] 16 45 3100, 4100
J
Over 7 to 10 [178 to 254], incl 80 [550] 105 [720] 15 40 4300, 9800
1 ⁄2 [38.1] and under 130 [900] 155 [1070] 14 35 4100, 4300,
1 1
Over 1 ⁄2 to 2 ⁄2 [38.1 to 63.5], incl 120 [830] 150 [1030] 14 35 9800
C
BD Over 2 ⁄2 to 4 [63.5 to 102], incl 110 [760] 140 [960] 14 35
Over 4 to 7 [102 to 178], incl 105 [720] 135 [930] 14 35
Over 7 to 10 [178 to 254], incl 100 [690] 130 [900] 14 35
A
Determined by the 0.2 % offset method.
B
The carbon content of all steels listed in this column may vary up to 0.55 % max, as agreed upon by the manufacturer and the purchaser.
B
Determined by the 0.2 % offset method.
C
Class BB, BC, BD hot-wrought; Class BB, BC cold-finished.
4. Materials and Manufacture
4.1 Melting Practice—The steel shall be made by one or more of the following primary processes: open-hearth, basic-oxygen,
or electric-furnace. any commercially viable primary steelmaking process. The primary melting may incorporate separate
degassing or refining and may be followed by secondary melting using electroslag remelting or vacuum arc remelting. Where
secondary melting is employed, the heat shall be defined as all of the ingots remelted from a single primary heat.
4.2 Discard—Sufficient discard shall be made to secure freedom from injurious piping and undue segregation.
4.3 Slow Cooling—Hot-wrought alloy bars shall, immediately after rolling, be allowed to cool to a temperature below the
critical range under suitable conditions to prevent injury by too rapid cooling.
4.4 Condition—Bars shall be furnished in one of the following conditions, as specified by the purchaser. Generally, size limits
for various methods of processing round bars are:
Hot-wrought or hot-wrought descaled 9 ⁄2 in. [241.3 mm], max
Cold-drawn ⁄8 to 4 in. [3.2 to 102 mm], incl
Cold-drawn, ground, and polished ⁄8 to 4 in. [3.2 to 102 mm], incl
Turned and polished ⁄4 to 9 in. [19.1 to 229 mm], incl
Turned, ground, and polished ⁄4 to 9 in. [19.1 to 229 mm], incl
4.5 Heat Treatment:
4.5.1 Heat treatment shall include quenching and tempering for all classes of material. The material shall be uniformly heated
to the austenitizing temperature, soaked for a sufficient length of time to produce the desired structure (a lot thus heated being
known as a “quenching charge”), and quenched in a suitable medium under substantially uniform conditions for each quenching
charge. The material shall then be uniformly reheated to the proper temperature for tempering (a lot thus reheated being known
as a “tempering charge”), and allowed to cool uniformly. The temperature selected for tempering shall be not less than 800 °F
[427 °C].
4.5.2 M
...