GB/T 4337-2015 English PDF (GBT4337-2015)

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GB/T 4337-2015: Metallic materials -- Fatigue testing -- Rotating bar bending method
GB/T 4337-2015
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.040.10
H 22
Replacing GB/T 4337-2008
Metallic materials - Fatigue testing - Rotating bar bending
method
(ISO 1143:2010, Metallic materials - Rotating bar bending fatigue testing,
MOD)
ISSUED ON: SEPTEMBER 11, 2015
IMPLEMENTED ON: JUNE 01, 2016
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 Terms and definitions ... 5
4 Symbols and designations ... 6
5 Test principle ... 7
6 Shape and size of specimen... 7
7 Preparation of specimens ... 8
8 Accuracy of test equipment ... 11
9 Heating and temperature measuring devices ... 11
10 Test procedures ... 11
11 Presentation of test results ... 14
12 Test report ... 15
Annex A (normative) Verification of bending distance of rotary bending fatigue testing
machine ... 22
Metallic materials - Fatigue testing - Rotating bar bending
method
1 Scope
This Standard specifies the rotational bending fatigue test method for metallic materials.
This Standard applies to the fatigue test of metallic materials under the condition of
rotating and bending of specimens at room temperature and high temperature in air.
Rotational bending fatigue tests in other environments (such as corrosion) can also be
performed with reference to this Standard.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
GB/T 3075, Metallic materials - Fatigue testing - Axial force-controlled method
(GB/T 3075-2008, ISO 1099:2006, MOD)
GB/T 10623, Metallic material - Mechanical testing - Vocabulary (GB/T 10623-
2008, ISO 23718:2007, MOD)
GB/T 13634, Metallic materials - Calibration of force-proving instruments used for
the verification of uniaxial testing machines (GB/T 13634-2008, ISO 376:1999, IDT)
GB/T 24176, Metallic materials - Fatigue testing - Statistical planning and analysis
of data (GB/T 24176-2009, ISO 12107:2003, IDT)
GB/T 26077, Metallic materials - Fatigue testing - Axial-strain-controlled method
(GB/T 26077-2010, ISO 12106:2003, MOD)
3 Terms and definitions
For the purposes of this document, the terms and definitions defined in GB/T 3075,
GB/T 10623, GB/T 24176 and GB/T 26077 as well as the followings apply.
3.1 fatigue
process of changes in properties which can occur in a metallic material due to the
test medium shall be indicated in the report.
6.2 Dimensions of specimens
Specimens used in the same batch of fatigue tests shall have the same diameter, the
same shape and dimensional tolerances.
To accurately calculate the applied force, the measurement of the actual minimum
diameter of each specimen shall be accurate to 0.01mm. Before the test, it shall be
ensured that the surface of the specimen is not damaged when measuring the size of the
specimen.
For cylindrical specimens subjected to constant bending (see Figures 4 and 5), the
parallelism of the test section shall be guaranteed to be within 0.025mm. For other
shapes of cylindrical specimens (see Figure 1), the parallelism of the test part shall be
ensured within 0.05mm. The radius of the transition arc between the specimen holding
part and the experimental part shall not be less than 3d. For funnel-shaped specimens,
the arc radius of the test section shall not be less than 5d.
Figure 8 shows the shape and dimensions of the cylindrical specimen. Recommended
diameters d are 6mm, 7.5mm and 9.5mm. The deviation of diameter d shall not be
greater than 0.005d. Figure 9 shows the recommended high temperature fatigue test
circular arc smooth specimen (hazardous section).
Since the shape and size of notched specimens are not standardized, this Standard does
not cover notched fatigue tests. However, the fatigue testing procedures described in
this Standard can be applied to notched fatigue specimens.
7 Preparation of specimens
7.1 General
When determining the rotating bar bending fatigue properties of the material, the
following requirements for specimen preparation shall be noted. If the test procedure is
designed to determine the effect of a factor (surface treatment, oxidation and so on) that
is not in line with the sample preparation requirements, it is possible to deviate from
the specimen preparation requirements. Any deviation in each case shall be noted in the
report.
7.2 Sampling and marking
Sampling location, sampling direction and sample type shall be in accordance with the
relevant product standards or mutual agreement.
Sampling from semi-finished products or parts can affect the test results. It is therefore
necessary to take samples under fully informed conditions.
Sampling drawings shall be attached to the test report. It shall be clearly stated of:
- Location of each specimen;
- Characteristic direction of semi-finished product processing (rolling direction,
extrusion direction and so on);
- Identification of each sample.
Specimens shall be identified at each stage of processing. Reliable methods shall be
taken to ensure that the marking will not disappear during processing or affect the
results of the test. Each specimen needs to be engraved with unique marks on both ends
of the specimen when the final machining is completed. It is ensured that each half of
the specimen can be clearly identified after fracture of the specimen fatigue test.
7.3 Processing
7.3.1 Heat treatment of test materials
If heat treatment is performed after rough machining, it is recommended that final
polishing be performed after heat treatment. Otherwise, heat treatment shall be carried
out under vacuum or inert gas to prevent oxidation of the specimen. Heat treatment
shall not alter the microstructural properties of the material under study. Details of heat
treatment and machining procedures shall be noted in the test results.
7.3.2 Machining requirements
Machining may generate residual stresses on the surface of the specimen. These
residual stresses may be caused by thermal gradients during the machining phase or by
material deformation or changes in the microstructure. The effect of residual stress does
not need to be considered in high temperature fatigue test. This is because the residual
stress has been fully or partially released during the specimen holding process. However,
suitable machining methods shall be adopted to reduce residual stress, especially in the
final polishing stage. For harder materials, it is better to select the grinding process.
- Grinding: The machining allowance of the specimen before grinding is +0.1mm.
Grinding is carried out at a grinding speed not exceeding 0.005mm/r.
- Polishing: Remove the final 0.025mm machining allowance with different
sandpapers with progressively smaller grains. It is recommended that the final
polishing direction shall be along the axis of the specimen.
Changes in material microstructure may be caused by temperature increase and strain
hardening during machining. It may undergo a phase change or in more cases
recrystallization of the surface. The test is invalid because the tested material is no
longer the original material. Some materials affect mechanical prope...