Designation: A 770/A770M – 86 (Reapproved 2001)

Standard Specification for

Through-Thickness Tension Testing of Steel Plates for
Special Applications1
This standard is issued under the fixed designation A 770/A770M; 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 (e) 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 except for plates subjected to heat treatment by quenching and

1.1 This specification2 covers the procedures and accep- tempering. Two tests shall be required from each quenched-
tance standards for the determination of reduction of area using and-tempered plate. The tests shall be representative of the
a tension test specimen whose axis is perpendicular to the plate in its final condition.
rolled surfaces of steel plates 1 in. [25 mm] and greater in 4.1.2 When plates are furnished by the manufacturer in an
thickness. The principal purpose of the testing is to provide a unheat-treated condition and qualified by heat-treated speci-
measure of the resistance of a steel plate to lamellar tearing. mens (including normalized, normalized and tempered, and
(See Appendix X1.) quenched and tempered), two tests shall be required from each
1.2 The values stated in either inch-pound units or SI units plate-as-rolled.
are to be regarded as standard. Within the text, the SI units are NOTE 1—The term “plate-as-rolled’’ refers to the unit plate rolled from
shown in brackets. The values stated in each system are not a slab or directly from an ingot. It does not refer to the condition of the
exact equivalents; therefore, each system must be used inde- plate.
pendently of the other. Combining values from the two systems 4.2 Location of Test Coupons—Take one test coupon at each
may result in nonconformance with the specification. end of each plate as defined in 4.1. Take the test coupons from
1.3 This specification is expressed in both inch-pound and the center of the plate width.
SI units. However, unless the order specifies the applicable 4.3 Orientation of Test Specimens—The longitudinal axis of
“M” specification designation (SI units), the material shall be the reduced section of the test specimens shall be perpendicular
furnished to inch-pound units. to the rolled surface of the plate.
4.4 Preparation of Test Specimens:
2. Referenced Documents
4.4.1 Welded Prolongations—When required, join welded
2.1 ASTM Standards: prolongations to the surface(s) of the plate being tested. The
A 370 Test Methods and Definitions for Mechanical Testing joining method used shall be one which results in a minimal
of Steel Products3 heat-affected zone in the portion of the plate to be tested.
3. Ordering Information Shielded metal arc, friction, stud, or electron-beam welding
methods have proven to be suitable.
3.1 The inquiry and order shall include the following, if 4.4.2 Types of Test Specimens:
required: 4.4.2.1 Three types of standard round tension test specimens
3.1.1 Supplementary requirements that are available to meet are shown in Fig. 1 and Table 1. For Types 1 and 2 specimens,
end use requirements (see S1 through S5). locate the center of the length of the reduced section at the
3.1.2 Special requirements agreed upon between the manu- approximate mid-point of the plate thickness. For Type 3
facturer and the purchaser. specimens, locate the weld fusion line of one plate surface
4. Tension Tests within 1⁄4 in. [6 mm] of one end of the reduced section.
4.4.2.2 For plates from 1 in. [25 mm] to 11⁄4 in. [32 mm]
4.1 Number of Tests: inclusive in thickness, use either the 0.350-in. [8.75-mm] Type
4.1.1 Two tests shall be required from each plate-as-rolled, 1 specimen or the 0.500-in. [12.5-mm] Type 2 specimen.
4.4.2.3 For plates over 11⁄4 in. to 2 in. [50 mm] inclusive in
1
This specification is under the jurisdiction of ASTM Committee A-1 on Steel, thickness, use the 0.500-in. [12.5-mm] Type 2 specimen.
Stainless Steel, and Related Alloys and is the direct responsibility of Subcommittee 4.4.2.4 For plates greater than 2 in. [50 mm] in thickness,
A01.11 on Steel for Boilers and Pressure Vessels.
Current edition approved Feb. 28, 1986. Published April 1986. Originally use the Type 3 specimen.
published as A 770 – 80. Last previous edition A 770 – 82. 4.4.3 Alternative Test Specimens—The alternative test
2
For ASME Boiler and Pressure Vessel Code applications, see related Specifi- specimens in Fig. 2 and Table 2 may be used in place of the
cation SA-770/SA-770M in Section II of that Code.
3
Annual Book of ASTM Standards, Vol 01.03.
standard specimens in Fig. 1 and Table 1, subject to agreement

Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.

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 A 770/A770M

NOTE—For Type 3 only one welded prolongation may be needed,

depending upon plate thickness.
FIG. 1 Standard Round Tension Test Specimens

TABLE 1 Schedule of Standard Test Specimens, Inches

[Millimetres]A

Specimen Type
1 2 3 FIG. 2 Alternative Tension Test Specimens
Plate thickness(t) 1 # t # 11⁄4 1<t#2 2<t
Diameter(D) 0.350 [8.75] 0.500 [12.5] 0.500 [12.5]
Radius, minimum(R) 1⁄4 [6] 3⁄8 [10] 3⁄8[10]
described in Table 2. A series of two or more Type F specimens
Length of reduced 13⁄4 [45] 21⁄4 [60] 21⁄4[60] may be used to cover the full thickness of the plate. The length
section(A) of the reduced section (A), as shown in Fig. 2 and specified in
A
See Test Methods and Definitions A 370 (Fig. 5 for further details and Fig. 6 for Table 2, is the length of the reduced section excluding the
various types of ends). machined radius (R). Within the plate thickness dimension
specified for each test specimen type, either the button-head
between the manufacturer and the purchaser. thickness, the reduced section length, or the machined radius
4.4.3.1 For plates over 2 in. [50 mm] in thickness, Type A or may be varied. In all cases, the minimum length of the reduced
Type B specimens may be used. The Type A specimen provides section must be as specified in Table 2 to maintain a minimum
a reduced section length greater than the plate thickness. The length to diameter ratio (see Appendix X2.2).
Type B specimen provides a reduced section length of 21⁄4in.
[57 mm] with its center at the mid-thickness of the plate. Over 5. Acceptance Standards
a minimum plate thickness determined by the specimen end 5.1 Each tension test shall have a minimum reduction of
configuration, no welded prolongations may be needed for the area no less than 20 %. If the reduction of area of both tests is
Type B specimen. For plates over 41⁄4 in. [108 mm] in less than 20 %, no retest shall be permitted. If the reduction of
thickness, the standard round tension test specimen Type C area of one of the two tests from a plate is less than 20 %, one
may be used. For plates over 6 in. [150 mm] in thickness, a retest of two additional specimens taken from a location
series of two or more Type A or Type C specimens with adjacent to the specimen that failed may be made, and both of
reduced sections of 4 in. [100 mm] or less may be used to cover these additional specimens shall have a reduction of area of
the full thickness of the plate. The number of tests required will 20 % or more.
depend upon the thickness of the plate being tested and the 5.2 Failures occurring in the prolongations, the weld, or in
reduced section length selected. the fusion line shall be considered as a “no-test,’’ and an
4.4.3.2 For plates over 1 in. [25 mm] in thickness, a series additional specimen shall be tested.
of button-head specimens shown in Fig. 2 and Table 2 may be
used. The test specimen type to be used, Type D, Type E, or 6. Marking
Type F, is determined by the nominal plate thickness as 6.1 Plates accepted in accordance with this specification

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 A 770/A770M
TABLE 2 Schedule of Alternative Test Specimens, Inches [Millimetres]

Specimen Type
AA BA CB D E F
Plate thickness(t) 2<t 2<t 41⁄4 < t 1 # t # 1 3⁄4 13⁄4 < t # 21⁄2 21⁄2 < t
[50 < t] [50 < t] [108 < t] [25 # t # 45] [45 # t # 64] [64 < t]
Diameter(D) 0.500 [12.5] 0.500 [12.5] 0.500 [12.5] 0.250 [6.25]C 6 0.350 [8.75]C 6 0.500 [12.5]C
0.005 [0.10] 0.007 [0.18] 6 l0.010
[0.25]
Radius, min(R) ⁄ [10]
38 ⁄ [10]
38 ⁄ [10]
1 16 optional optional optional
Length of reduced section t + 1⁄4 min 21⁄4 [60] t − 11⁄2 0.625 [16] 0.875 [22] 1.250 [32]
min(A) [t + 6] [t − 38]
A
See Test Methods and Definitions A 370 (Fig. 5 for further details and Fig. 6 for various types of ends).
B
See Test Methods and Definitions A 370 (Fig. 6, specimen 3 for further details).
C
The reduced section may have a gradual taper from the ends toward the center, with the ends not more than 1 % larger in diameter than the center (controlling
dimension).

shall be identified by stamping or stenciling ZT adjacent to the marking required by the applicable product specification.

SUPPLEMENTARY REQUIREMENTS

These requirements apply only when specified by the purchaser.

S1. Tensile Strength Requirements S4. Number of Tests

S1.1 Tensile strength shall conform to a minimum value S4.1 A greater number of tests than indicated in 4.1 may be
which is subject to agreement between the manufacturer and specified subject to agreement between the manufacturer and
purchaser. purchaser.
S2. Yield Strength Requirements
S5. Location of Test Coupons
S2.1 Yield strength, for plates 2 in. [50 mm] and over in
thickness, shall conform to a minimum value which is subject S5.1 Test coupons from locations in addition to those
to agreement between the manufacturer and purchaser. specified in 4.2 may be specified subject to agreement between
the manufacturer and purchaser.
S3. Reduction of Area Requirements
S3.1 A minimum reduction of area limit higher than that in
5.1 may be specified subject to agreement between the manu-
facturer and purchaser.

APPENDIXES

(Nonmandatory Information)

X1. LAMELLAR TEARING ADJACENT TO WELDS

X1.1 Introduction material underneath the weld, in a direction generally parallel

X1.1.1 Lamellar tearing is a particular type of cracking that to the plate surface and often slightly outside the heat-affected
occurs under the weld of a steel plate weldment. It is generally zone. Lamellar tearing generally has a step-like appearance
caused by strain induced in the thickness direction resulting consisting of “terraces’’ (cracks running parallel to the plate
from shrinkage of the weld deposit and by the restraint surface) and “walls’’ (cracks which connect the individual
imposed by the components that comprise the weldment. High terraces). The tearing may remain completely subsurface or
restraint increases the possibility of lamellar tearing. However, appear at plate edges or at weld toes.
lamellar tearing is not solely confined to highly restrained
X1.3 Inclusions
weldments. Lamellar tearing may also result from loads on the
plate surface. X1.3.1 The step-like cracking characteristic of lamellar
tearing is usually considered to result from small elongated
X1.2 Characteristics of Lamellar Tearing nonmetallic inclusions that are normally present in the steel.
X1.2.1 Lamellar tearing normally occurs in susceptible Strains in the through-thickness direction can cause individual

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 A 770/A770M
inclusions to fractures or decohere from the surrounding steel X1.4 Steel Manufacturing Processes
matrix, thus initiating a void. Further strain can cause the
X1.4.1 Special steel-making processes are available for
remaining metallic ligaments to shear or rupture, resulting in
improving the through-thickness ductility. The more common
the step-like fracture appearance.
processes, used singly or in combination, are: (1) low sulfur
X1.3.2 A high or concentrated inclusion content in the steel
produces planar regions of poor ductility parallel to the steel practices; (2) inclusion shape control; (3) electroslag or
surface. On the other hand, a reduction in the magnitude and vacuum arc remelting; and (4) vacuum degassing. The steel-
concentration of these inclusions to a low level tends to making processes are not all intended for the same purpose, but
preclude any easy fracture path along the low ductility inclu- will improve the through-thickness ductility to various degrees
sions and the steel exhibits improved ductility in a through- depending on the process used.
thickness direction.
X1.3.3 The extent of nonmetallic inclusions depends on the X1.5 Through-Thickness Ductility Requirements
type of steel. In silicon semikilled or fully killed steels, these X1.5.1 Susceptibility to lamellar tearing depends on many
inclusions are primarily oxides (present as silicates) and factors (for example, restraint, welding conditions, etc.) and,
sulfides (present as manganese sulfides). For aluminum-silicon consequently a specific through-thickness ductility require-
killed steels, these inclusions are primarily sulfides (manganese
ment does not provide a guarantee against lamellar tearing. The
sulfides). To improve the through-thickness ductility and thus
most widely accepted method of measuring the material
the resistance of the steel to lamellar tearing, it is necessary to
ductility factor of susceptibility to lamellar tearing is the
reduce the level of the nonmetallic inclusions. To provide a
high resistance to lamellar tearing may require the use of reduction of area of a round tension test specimen oriented
special steel-making processes that can reduce the oxygen and perpendicular to the rolled surface of a plate.
sulfur contents in the steel to very low levels.

X2. TESTING PARAMETERS AFFECTING REDUCTION OF AREA VALUES

X2.1 Variability of Through-Thickness Properties plate according to the described testing procedures using only
X2.1.1 Through-thickness tension test results, and in par- a minimum value requirement. The potential variability of the
ticular the reduction of area determination as provided for in test results also increases the possibility that subsequent testing
this specification, are subject to substantially greater scatter of a steel plate qualified according to this specification may
than would normally be expected from standard tension tests of produce results that do not meet the specified acceptance
a plate in the longitudinal or transverse direction. This scatter standard.
of test results is due in part to the inherent variability of the
distribution of the nonmetallic inclusions discussed in X1.3. X2.2 Effects of Test Specimen Design
For example, those nonmetallic inclusions that form during the X2.2.1 Two main factors considered in the selection of test
solidification phase of the steelmaking process tend to occur specimen geometry were the diameter and the slenderness
with a higher frequency in the area of final solidification. ratio. It is generally accepted that there is a diameter effect on
X2.1.2 Test specimen design may also have an effect on the reduction-of-area values such that a smaller diameter specimen
test results. Some of these factors are discussed in X2.2. generally yields a higher average reduction in area value. It is
Operator technique will also be a factor in increasing scatter, also accepted that smaller diameter test specimens will tend to
particularly in the measurement of the final diameter of the test give greater variability to the resulting reduction in area values.
specimen. Because of the effect of inclusions on the fracture Because these relationships between the test specimen diam-
process, the appearance of the final fracture may be quite eter and the average and variability of the test result have not
different than the classical cup-cone fractures common to been satisfactorily quantified at this time, the same minimum
longitudinal and transverse tension testing. For those materials requirement has been applied to all test specimen diameters.
with approximately 20 % reduction of area, the final diameter X2.2.2 The slenderness ratio (reduced section length/
measurement may require a substantial amount of judgment on reduced section diameter) is known to affect the reduction in
the part of the test operator. area values when below a minimum value. This minimum
X2.1.3 In view of the potential variability of the through- value may be from 1.5 to 2.5, depending on the material.
thickness reduction of area test results, it is recognized that two Below this minimum value, the reduction at the failure point in
tests per plate are not sufficient to fully characterize the the reduced section is restrained by the larger cross section
through-thickness ductility of that plate. The number of tests away from the reduced section. A minimum slenderness ratio
and test positions have not been established that would provide of 2 was selected for the standard Type 2 specimen to allow a
a good estimate of both the mean and the variability of 0.500-in. [12.5-mm] diameter specimen to be used on a 1-in.
through-thickness tensile reduction of values of a plate. There- [25-mm] plate. A minimum slenderness ratio of 2.5 was
fore, an average value requirement is not included in this selected for the collar-button specimens (Types D, E, and F) to
specification. The intent of this specification is to qualify a ensure that this effect is minimized for these test specimens.

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 A 770/A770M
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