GB/T 16865-2023 Test pieces and methods for tensile test for wrought aluminum, magnesium and their alloy products
1 Scope
This document specifies test piece requirements and test methods for tensile test of wrought aluminum, magnesium and their alloy products.
This document is applicable to tensile testing at room temperature, elevated temperature and low temperature of wrought aluminum, magnesium and their alloy sheets, strips, foils, tubes, bars, sections, wires, forgings and other products.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 3246
(All parts) Inspection method for structure of wrought aluminum and aluminum alloy products
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 10623 Metallic material - Mechanical testing - Vocabulary
GB/T 12160-2019 Metallic materials - Calibration of extensometers systems used in uniaxial testing
GB/T 16825.1-2022 Metallic materials - Calibration and verification of static uniaxial testing machines - Part 1: Tension/compression testing machines - Calibration and verification of the force-measuring system
GB/T 22638.11 Test methods for aluminum and aluminum alloy foils - Part 11: Determination of mechanical properties
GB/T 34104-2017 Metallic materials - Verification of the alignment of testing machines
JJG 139 Tension, compression and universal testing machines
JJG 475 Verification regulation of electronic universal testing machine
JJG 762 Verification regulation for extensometer
JJG 1063 Verification regulation of electro-hydraulic servo universal testing machines
3 Terms and definitions
For the purpose of this standard, the terms and definitions given in GB/T 10623 apply.
4 Methods
Apply axial tension to the test piece (see Figure 1) and determine the mechanical properties of the test piece. Tensile test differentiates among the following three test temperature ranges:
——room temperature, i.e. the temperature range of 10°C ~ 35°C, at which one or several mechanical properties of the test piece, such as tensile strength, proof strength (non-proportional extension), elongation after fracture, reduction of area, yield point extension, total extension at maximum force, plastic extension at maximum force, elastic modulus, plastic strain ratio and strain-hardening index are determined;
——elevated temperature, i.e. the temperature range of > 35°C ~ 500°C, at which one or several mechanical properties of the test piece, such as tensile strength, proof strength (non-proportional extension), elongation after fracture, and reduction of area are determined; and
——low temperature, i.e. the temperature range of -196°C~<10°C, at which one or several mechanical properties of the test piece, such as tensile strength, proof strength (non-proportional extension), elongation after fracture, and reduction of area are determined.
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Key:
F——force;
CL——center line of the gripping system and longitudinal axis of the test piece;
1——grip;
2——test piece;
3——extensometer.
Figure 1 Example of tensile test
5 Apparatus
5.1 Testing machine
5.1.1 The force-measuring system of the testing machine shall be calibrated as specified in JJG 139, JJG 475 or JJG 1063. The accuracy of the force-measuring system of the testing machine used for determining the tensile properties of aluminum foil products at room temperature shall reach or be better than Class 0.5 as specified in GB/T 16825.1-2022, and that of the force-measuring system of the testing machine used for determining the mechanical properties of other products shall reach or be better Class 1.
5.1.2 The maximum load required for the test should be within the range of 10% ~ 90% of the maximum load of the testing machine.
5.1.3 The testing machine used for determining the elastic modulus or the mechanical properties of aviation and aerospace materials shall be tested for coaxiality as specified in GB/T 34104-2017. The coaxiality of the testing machine used for determining the elastic modulus shall reach or be better than Class 5, and that of the testing machine used for determining the mechanical properties of aviation and aerospace materials shall reach or be better than Class 10.
5.2 Extensometer
5.2.1 The extensometer system shall be calibrated as specified in JJG 762. The accuracy of the extensometer system in determining the elastic modulus shall reach or be better than the Class 0.5 as specified in GB/T 12160-2019, and that of the extensometer system in determining the other mechanical properties shall reach or be better the Class 1.
5.2.2 In the determination of elastic modulus, the extensometer system shall be able to measure the average deformation of at least two opposite sides of the test piece. When the plastic strain ratio is measured by automatic method, the extensometer system shall be able to measure the deformation in the length direction and the deformation in the breadth direction of the rectangular test piece, and the extensometer for measuring the deformation in the breadth direction should be able to measure the average deformation at both ends and the middle of the gauge length of the test piece.
5.2.3 The gauge length (Le) of the extensometer should be greater than half of the original gauge length (L0) and not greater than the original gauge length (L0). When using extensometer to measure the elongation after fracture, the gauge length (Le) of the extensometer shall be equal to the original gauge length (L0).
5.2.4 The part of the extensometer used for tensile tests at elevated temperature and low temperature which projects beyond the heating device or cooling device shall be resistant to airflow interference.
5.2.5 Non-contact extensometer should be used to measure the tensile properties of aluminum foil at room temperature.
5.3 Grips
Wedge grips (see Figure 2), parallel jaw faces (see Figure 3), shouldered holders (see Figure 4), collar grips (see Figure 5), screwed grips (see Figure 6), pin grips (see Figure 7), etc. may be selected for the test purposes. The gripping faces of wedge grips and parallel jaw faces may be serrated and smooth rubber.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Methods
5 Apparatus
6 Test piece
7 Test procedures
8 Result judgment
9 Test report
Annex A (Informative) Estimation method of crosshead displacement rate
