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GB/T 232-2010 PDF in English


GB/T 232-2010 (GB/T232-2010, GBT 232-2010, GBT232-2010)
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GB/T 232-2010: PDF in English (GBT 232-2010)

GB/T 232-2010
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.040.10
H 23
Replacing GB/T 232-1999
Metallic Materials - Bend Test
(ISO 7438:2005, MOD)
ISSUED ON: SEPTEMBER 2, 2010
IMPLEMENTED ON: JUNE 1, 2011
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative References ... 5 
3 Symbols and Instructions ... 5 
4 Principle ... 6 
5 Test Equipment ... 7 
6 Test Pieces ... 8 
7 Test Procedure ... 10 
8 Evaluation of Test Result ... 12 
9 Test Report ... 12 
Appendix A (Informative) A Comparison List of Chapter No. in this Standard and
ISO 7438:2005 ... 14 
Appendix B (Informative) Determination Method of Bending Angle through
Measurement of Displacement of Bent Indenter ... 16 
Foreword
The modification of this Standard adopts international standard ISO 7438:2005
Metallic Materials - Bend Test (English version) as a reference.
This Standard was re-drafted in accordance with ISO 7438:2005. In order to make it
convenient for comparison, Appendix A provides a comparison list between the chapter
No. in this national standard and the Chapter No. in the international standard.
The main technical differences between this Standard and the international standard
are as follows:
---Chapter 2 “Normative References” is added;
---Figure 3 and Figure B.1 are added to Chapter 3;
---5.5 “other bending devices (for example, flap-type bending device) that comply
with the principle of bend test may also be adopted” is added;
---“The cutting location and direction of test piece shall comply with the
requirements of relevant product standards. If it is not specifically stipulated,
steel products shall comply with the requirements in GB/T 2975.” is added to
6.1.
In order to make it convenient to be used, this Standard makes the following editorial
modifications:
---The phrase “this International Standard” is modified into “this Standard”;
---Decimal point “.” is used to replace comma “,”, which serves as decimal point;
---The foreword in the international standard is deleted.
This Standard serves as a replacement of GB/T 232-1999 Metallic Materials - Bend
Test.
This amendment of this Standard makes the following modifications in technical
content based on GB/T 232-1999:
---The term “flexural center” is deleted;
---The formula that determines test piece’s length is deleted;
---The stipulations of test piece’s thickness are modified;
---The stipulations of fillet radius value of rectangular test piece are added;
Metallic Materials - Bend Test
1 Scope
This Standard stipulates the test method for the determination of metallic materials’
ability of withstanding plastic deformation in bending.
This Standard is applicable to bend test of test pieces of metallic materials stipulated
in relevant product standards. However, it is not applicable to bend test of metal pipes
and metal welded joints. The bend test of metal tubes and metal welded joints shall be
stipulated by other standards.
2 Normative References
Through the reference in this Standard, clauses of the following documents become
clauses of this Standard. In terms of references with a specific date, all the subsequent
modification sheets (excluding the corrected content) or the revised editions are not
applicable to this Standard. However, all parties that reach an agreement in
accordance with this Standard are encouraged to explore the possibility of adopting
the latest version of these documents. In terms of references without a specific date,
the latest version is applicable to this Standard.
GB/T 2975 Steel and Steel Products - Location and Preparation of Test Pieces for
Mechanical Testing (GB/T 2975-1998, eqv ISO 377: 1997)
3 Symbols and Instructions
The symbols adopted in this Standard, and the instructions of the symbols are shown
in Table 1, Figure 1, Figure 2, Figure 3 and Figure B.1.
Table 1 -- Symbols and Instructions
Symbols Instructions Unit
Test piece’s thickness or diameter (or inscribed circle diameter of
polygonal cross section) mm
b Test piece’s width mm
L Test piece’s length mm
l Distance between rollers mm
D Diameter of bent indenter mm
a Bending angle ()
r Bending radius of test piece after bending mm
f Displacement distance of bent indenter mm
c Before test, the distance between the horizontal plane where the roller’s mm
5.3 V-shaped Mold Bending Device
The angle of V-shaped groove of the mold shall be (180 - a) (see Figure 2). Bending
angle (a) shall be stipulated in relevant product standards.
The supporting edges of the mold shall be rounded; the rounding radius shall be (1 ~
10) times of the test piece’s thickness. The width of the mold and bent indenter shall
be more than the width or diameter of the test piece. In addition, the mold and bent
indenter shall have sufficient hardness.
5.4 Clamp-type Bending Device
The device is constituted of clamp and bent indenter, which has sufficient hardness
(see Figure 3). A lever of force application may be allocated. The diameter of bent
indenter shall comply with the requirements of relevant product standards; the width of
bent indenter shall be more than the width or diameter of test pieces.
Sine the position of the left end face of the clamp will affect the test result, the left end
face (see Figure 3) of the clamp cannot reach or exceed the bent indenter’s central
vertical line.
5.5 Other bending devices (for example, flap-type bending device) that comply with
the principle of bend test may also be adopted.
6 Test Pieces
6.1 General Requirements
Test pieces of circular, square, rectangular or polygonal cross section shall be used in
test. The cutting location and direction of test piece shall comply with the requirements
of relevant product standards. If it is not specifically stipulated, steel products shall
comply with the requirements in GB/T 2975. Parts where material performance is
affected by shearing or flame cutting, or similar operations, shall be removed. If the
test result is not affected, it is allowed to retain the affected parts.
6.2 Edges of Rectangular Test Pieces
The surface of test pieces shall not manifest any scratch or damage. The edges of
square, rectangular and polygonal cross section test pieces shall be rounded; the
rounding radius cannot exceed the following numerical values:
---1 mm, when test piece’s thickness is less than 10 mm;
---1.5 mm, when test piece’s thickness is more than or equals to 10 mm, and less
than 50 mm;
---3 mm, when test piece’s thickness is not less than 50 mm.
7.3 In the test that bends test piece to the stipulated bending angle, the test piece shall
be placed on the two rollers (see Figure 1) or the V-shaped mold (see Figure 2); test
piece’s axes shall be vertical to the bent indenter’s axes. In the midpoint between the
two supports, the bent indenter continuously applies force on the test piece to make it
bent, till the stipulated bending angle is reached. Bending angle (a) may be calculated
through the measurement of the displacement of the bent indenter, as it is shown in
Appendix B.
The method shown in Figure 3 may be adopted to conduct the bend test. Fixate one
end of the test piece; bend it around the bent indenter. It may be bent across the bent
indenter, till it reaches the stipulated bending angle (see 5.4 for details).
In bend test, slowly apply the bending force, so that materials can freely conduct plastic
deformation.
When there is a dispute, test rate shall be (1 ± 0.2) mm/s.
If it is impossible to directly reach the stipulated bending angle through the above-
mentioned methods, place the test piece between two parallel pressing plates (see
Figure 5); continuously apply force onto both ends, so that the test piece would further
bend, till it reaches the stipulated bending angle.
7.4 In test that test piece is bent till its two arms are mutually parallel, firstly,
preliminarily bend the test piece; then, place the test piece between two parallel
pressing plates (see Figure 5); continuously apply force onto both ends, so that the
test piece would further bend, till the two arms become parallel (see Figure 6). In the
test, an internal insert may, or, may not be added. The thickness of the insert equals
to the stipulated diameter of bent indenter, unless it is otherwise stipulated in product
standards.
7.5 In test that test piece is bent till its two arms directly contact with each other, firstly,
preliminarily bend the test piece; then, place the test piece between two parallel
pressing plates; continuously apply force onto both ends, so that the test piece would
further bend, till the two arms directly contact with each other (see Figure 7).
Figure 5
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.