Testing items and testing standards for stainless steel types
As stainless steel structural steel commonly used in engineering, what are its testing standards?
1. Size, shape, weight and allowable deviations
The size, shape, weight and allowable deviation of stainless steel plates should comply with the regulations of GB/T709. The size, shape, weight and allowable deviation of the steel strip and its sheared steel plate shall comply with the provisions of GB/T709. The size, shape, weight and allowable deviation of section steel should comply with the regulations of GB/T706 and GB/T11263.
2. Grade and chemical composition
Steel types and chemical compositions (smelting analysis) in different delivery states should comply with the provisions of Tables 1 to 5 of GB/T714. The carbon equivalent weight (CEV) of each grade of steel should be consistent with the amount in GB/T714 in Table 6. Except for weathering steel grades, when the carbon content is not greater than 0.12%, the welding crack sensitivity index is used instead of the carbon equivalent to evaluate the weldability of the steel. The allowable deviation of the chemical composition of finished steel products shall comply with the provisions of GB/T222.
3. Smelting method
Steel is smelted in a converter or electric furnace and should be refined outside the furnace.
4. Mechanical properties
The mechanical properties of steel should comply with the provisions of Table 8 of GB/T714. Charpy impact absorbed energy, calculated as the arithmetic mean of a set of three specimens, allowing an individual value for a specimen to be lower than the value specified in Table 8, but not less than 70% of the specified value. The Charpy impact test of steel plates with a thickness less than 12 mm shall be applied to auxiliary specimens. The cross-sectional shrinkage rate in the thickness direction of the steel shall comply with the provisions of GB/T5313.
5. Surface quality
The surface of the steel shall not have harmful defects that may affect its use, and the steel shall not have delamination visible to the naked eye. The surface of the steel is allowed not to hinder the inspection of surface defects and other local defects, but its depth should not be greater than half of the steel thickness tolerance, and the minimum allowable thickness of the steel should be ensured. Steel surface defects are allowed to be removed by grinding and other methods. The cleaning should be smooth and without edges. The cleaning depth should not be greater than the negative deviation of the steel thickness, and the minimum allowable steel thickness should be ensured. Defects are allowed in the steel strip, but the defective part shall not exceed 6% of the total length of each roll of steel strip.
6. Non-destructive testing
For single-rolled stainless steel plates with a thickness greater than 20mm, ultrasonic flaw detection should be carried out, in compliance with GB/T2970 standards, and the qualification level should not be lower than Level II. Whether it is the Eiffel Tower or the Nanjing Yangtze River Bridge, engineering structural steel could be used to create such a magnificent project at that time, but it is enough to show that it is extraordinary.
