GB/T 39130-2020 in English
VALIDMeasuring method for adhesion of zinc coating for galvanized products
- Issued on:2020-10-11
- Implemented on:2021-05-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
$214.00
《GB/T 39130-2020镀锌产品锌层附着性试验方法》由TC183（全国钢标准化技术委员会）归口，主管部门为中国钢铁工业协会。
Introduction
Analysis of the core content of the standard
| Test type | Applicable coating | Key parameters | Evaluation method |
|---|---|---|---|
| 180° bending test | Pure zinc/zinc-aluminum alloy | Indenter diameter = integer times of sample thickness | Visual inspection method (5-level system) |
| V-type bending test | Zinc-iron alloy | Bending angle 60°-75° | Tape method/reflectivity method |
Key Technical Points
1. Specimen Preparation Specifications
Specimen dimensions must meet the following requirements: width 25-200mm (100/150mm recommended), length ≥ 2 times the width. Before the test, the specimen should be conditioned at 23±2℃, 50±5%RH for more than 24 hours.
2. Key parameters of bending test
V-type bending device Die angle selection:
- Thickness ≤1.0mm: 60° bending is recommended
- Thickness＞1.0mm: 75° bending is recommended
Arbitration test rate control is 1±0.2mm/s
Coating evaluation system
Key points for implementing the reflectivity method
When using a reflectivity meter with a spot area of 12×7mm, please note:
- Thickness ≤1.0mm: The long axis of the spot is parallel to the tape peeling direction
- Thickness＞1.0mm: The long axis of the spot is perpendicular to the tape peeling direction
When the tape powder width is L≥5mm is directly judged as level 4
Standard Evolution Analysis
This standard incorporates the reflectivity meter method into the evaluation system for the first time, which has better repeatability than the traditional visual method. Key technical breakthroughs are reflected in:
- Establish a quantitative correspondence between reflectivity and adhesion level
- Standardize the test orientation requirements of samples of different thicknesses
- Introduce the width of the tape powder as an auxiliary criterion
Implementation Suggestions
Quality control application case: In the production of a certain automobile plate, it was found that the zinc-iron alloy coating level 3 was unqualified. By adjusting the alloying process parameters (the furnace temperature was reduced by 15℃), the reflectivity value was increased from 42% to 49%, reaching the level 2 standard.
Suggestions for enterprises:
- Establish a standard spectrum comparison database
- Regularly calibrate the reflectance meter whiteboard
- Retest the disputed results at a constant temperature of 23℃
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