GB/T 38841-2020 in English
VALIDMechanical properties measurement—Room temperature tensile test of reacted Nb3Sn composite superconductors
- Issued on:2020-06-02
- Implemented on:2020-12-01
- File Format:PDF
- Delivery:Via email within 5 business days
$476.00
《GB/T 38841-2020力学性能测量 反应后的Nb3Sn复合超导线室温拉伸试验方法》由TC265（全国超导标准化技术委员会）归口，主管部门为中国科学院。
Introduction
Analysis of the core content of the standard
This standard is equivalent to IEC 61788-19:2013, which specifies the tensile test method for reacted Cu/Nb3Sn composite superconducting wires at room temperature, focusing on measuring the elastic modulus and 0.2% specified plastic elongation strength.
Key Technical Requirements
| Parameters | Requirements | Testing Equipment |
|---|---|---|
| Specimen size | Cross-sectional area 0.15-2.0mm², copper-non-copper volume ratio 0.2-1.5 | Micrometer (accuracy ±4μm) |
| Testing machine | Constant displacement rate 0.1-0.5mm/min | In accordance with ISO 7500-1 |
| Extensometer | Mass ≤ 30g, gauge length ≥ 12mm | Dual extensometer system preferred |
Key points of the test process
- Specimen preparation: Straighten and load into ceramic tube before heat treatment, and carefully remove after reaction to avoid pre-strain
- Insulation layer treatment: Completely remove the surface insulation layer before heat treatment (glass/ceramic fiber can be mechanically stripped)
- Clamping method: Soft soldering metal sleeve or direct clamping can be used, and axial alignment must be ensured
- Data acquisition: Unloading-reloading cycle in the strain range of 0.3%-0.4%
Mechanical parameter calculation method
Elastic modulus E: Calculated by the formula E=ΔF/(S0·Δε), where:
- ΔF: tensile force increment (N)
- S0: original cross-sectional area (mm²)
- Δε: strain increment
0.2% specified plastic elongation strength: determined by the initial loading line translation method (Rp0.2-0) or the unloading line translation method (Rp0.2-U).
Measurement uncertainty control
Uncertainty of key parameters verified by the international round-robin comparison test:
- Elastic modulus E0: 1.4% (N=17)
- Elastic modulus EU: 1.3% (N=15)
- Rp0.2-0: 1.5% (N=17)
- Rp0.2-U: 2.5% (N=13)
The data is valid only if the ratio of E0/EU is between 0.7-1.3.
Implementation recommendations
1. Equipment verification: Regularly calibrate the system using aluminum/titanium welding wires of known performance
2. Data validity check: Regression coefficient > 0.99, zero offset stress < 5MPa
3. Exception handling: When E0/EU is out of range, check the specimen clamping and extensometer installation
4. Report content: Must include key information such as copper-non-copper volume ratio, clamping method, extensometer type, etc.
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