GB/T 46428.1-2025 Metallic materials - Miniature specimens of plate and rod - Part 1: Fatigue test method English, Anglais, Englisch, Inglés, えいご
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ICS 13.220
CCS H 57
National Standard of the People's Republic of China
GB/T 46428.1-2025
Metallic materials - Miniature specimens of plate and rod - Part 1: Fatigue test method
金属材料 板状、棒状微型试样 第1部分：疲劳试验方法
Issue date: 2025-10-31 Implementation date: 2026-05-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
Introduction
1 Scope
2 Normative References
3 Terms and Definitions
4 Symbols
5 Principle
6 Specimens
7 Test Equipment
8 Test Procedure
9 Data Processing
10 Test Report
Appendix A (Informative) Recommended Specimens and Fixtures
References
1 Scope
This document describes the fatigue test method for miniaturized plate and bar specimens of metallic materials, and specifies the principle of the test method, specimens, test equipment, test procedure, data processing, and the content of the test report.
This document applies to the constant-amplitude low-cycle fatigue testing of funnel-shaped plate specimens of homogeneous, isotropic metallic materials with power-law stress-strain relationships, with thicknesses ranging from 0.6 mm to 2 mm. The low-cycle fatigue testing for bar specimens refers to GB/T 26077.
2 Normative References
The contents of the following documents, through normative references in this document, constitute essential provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including all amendments) applies.
GB/T 10623 Metallic Materials - Terminology for Mechanical Testing
GB/T 12160 Metallic Materials - Calibration of Extensometer Systems for Uniaxial Testing
GB/T 16825.1 Metallic Materials - Verification and Calibration of Static Uniaxial Testing Machines - Part 1: Tension/Compression Testing Machines - Calibration of Force Measuring Systems
GB/T 25917.1 Uniaxial Fatigue Testing Systems - Part 1: Dynamic Force Calibration
JJG 556 Verification Regulation for Axial Force Fatigue Testing Machines
3 Terms and Definitions
The terms and definitions established by GB/T 10623 and the following apply to this document.
3.1 Force-Displacement Hysteresis Loop
A curve depicting the relationship between force and displacement over the gauge section recorded during a single test cycle.
Note: The gauge section displacement is the product of the extensometer gauge length and the nominal strain. A typical force-displacement hysteresis loop is shown in Figure 1.
Figure 1 Typical Force-Displacement Hysteresis Loop
3.2 Force-Displacement Amplitude Curve
A curve depicting the relationship between force amplitude and displacement amplitude over the gauge section.
3.3 Unloading Stiffness
The slope of the force-displacement curve during the initial unloading segment.
Note: Linear fitting is performed using the force-displacement data within the 50% to 80% range of the maximum force during the initial unloading segment. The slope of this linear portion is the unloading stiffness. A typical unloading force-displacement curve is shown in Figure 2.
Figure 2 Typical Unloading Force-Displacement Curve
4 Symbols
The symbols and corresponding descriptions used in this document are listed in Table 1.
Table 1 Symbols and Descriptions
5 Principle
This method utilizes a funnel-shaped plate specimen where the root of the funnel is under uniaxial stress. Through a multi-stage cyclic test on a single specimen, the force amplitude - displacement amplitude curve is obtained. This curve determines the material's cyclic strength coefficient and cyclic strain hardening exponent, yielding the material's cyclic stress amplitude - strain amplitude relationship. Fatigue tests at different strain levels (nominal strain amplitudes) provide the nominal strain amplitude - life curve. The conversion relationship between force amplitude, displacement amplitude, and the equivalent strain amplitude at the specimen's funnel root allows calculation of the specimen's strain amplitude for each nominal strain amplitude level. Based on the cyclic stress amplitude - strain amplitude relationship, the equivalent stress amplitude at the specimen's funnel root is determined, ultimately deriving the material's Manson-Coffin law from the relationship between strain amplitude, stress amplitude, and life.
6 Specimens
6.1 Specimen Shape and Dimensions
6.1.1 Tests shall be conducted using funnel-shaped plate specimens. The specimen configuration is shown in Figure 3. The geometric dimensions of the specimens shall satisfy the following conditions:
a) No compressive buckling occurs;
b) The minimum thickness ensures the stability of the extensometer installed on the side of the specimen;
c) The gauge length (Lo) is determined according to the extensometer gauge length (lo), with lo greater than the funnel span (2R). To avoid the risk of compressive buckling, the gauge section length (Lo) shall not exceed 1.5 times the specimen width (1.5w).
6.1.2 The range and tolerances for specimen geometric dimensions are provided in Table 2. Appendix A provides specific recommended dimensions for funnel-shaped plate specimens.
Table 2 Specimen Geometric Dimensions
6.2 Specimen Preparation and Storage
6.2.1 Specimen Preparation
6.2.1.1 Specimens shall be cut from homogeneous raw materials or blanks.
6.2.1.2 The selected specimen preparation process shall minimize residual stresses in the specimen as much as possible.
6.2.1.3 The influence of specimen surface roughness on test results shall be minimized as much as possible. The average surface roughness Ra shall not be worse than 1 μm, the roughness Ra at the funnel root shall not be worse than 0.32 μm, and the surface roughness Ra on both sides in the thickness direction shall not be worse than 0.4 μm. Longitudinal polishing of the funnel root is recommended in the final stage of preparation.
6.2.1.4 If the test material requires heat treatment before testing, the material shall be heat-treated first and then machined into specimens. If the material's hardness is too high after heat treatment, making machining difficult, rough machining can be performed first, followed by precision machining after heat treatment.
6.2.2 Marking
Specimens shall be numbered, and the identification shall be unique. Suitable methods shall be used to mark specimens, ensuring that the marking does not affect the test results.
6.2.3 Dimensional Measurement
The dimensions of the specimens shall be measured. This measurement shall not alter the surface condition of the specimens.
6.2.4 Storage
After preparation, specimens shall be cleaned promptly and stored properly to prevent deformation, surface damage, or corrosion. Damage to specimens during transfer shall be
