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   For the purchase of people, it is very important to check the quality of the product, and for the purchase of stainless steel screws, it is also necessary to know how to detect the quality of stainless steel screws, so how to detect, we all know what methods? Today Xiaobian here to share with you a few points, on the stainless steel screw fastener inspection methods mainly have the following four:
First, appearance quality requirements
The inspection of the appearance of stainless steel screws is carried out from the appearance, electroplating and other aspects.
Two, stainless steel screw coating thickness test

1, measuring method: the amount of micrometer, vernier caliper, plug gauge, etc.
2, magnetic method: magnetic method to measure the coating layer thickness, is the use of magnetic thickness meter on the magnetic matrix of non-magnetic coating layer of non-destructive measurement.
3, microscopy method: microscopy method is called metallographic method, it is the fastener after etching, placed on the microscope with micromeasuring eyepiece metallographic microscope magnification, measure the thickness of the coating on the section.
4. Timed liquid flow method
  The timed liquid flow method is used to make the solution of the coating dissolved on the local surface of the coating, according to the time required for the local coating to dissolve, to calculate the thickness of the coating. There are coating drop method, anode dissolved Coulomb method.
   Three, stainless steel screw coating adhesion strength test
   There are many ways to evaluate the adhesion of coating and matrix metal, usually the following.
1. Friction polishing test;
2, file method test;
3, scratch method;
4. Bending test;
5. Thermal shock test;
6. Extrusion method.
Four, stainless steel screw coating corrosion resistance test
The corrosion resistance of the coating is tested by:
1, air explosion drying test;
2. Salt spray test (NSS test);
3, acid spray test (ASS test);
4. Accelerated acetate spray test (CASS test);
5, corrosion paste corrosion test (CORR test);
6, liquid drip corrosion test;
7, stain test, inter dip corrosion test and so on.