For those who purchase, it is very important to check the quality of the product. For the purchase of stainless steel screws, it is also necessary to know how to check the quality of stainless steel screws. How do you know how to detect it? This will give you some points. There are four main methods for testing stainless steel screw fasteners:
First, the appearance quality requirements
The inspection of the appearance of stainless steel screws is carried out in terms of appearance, plating and other aspects.
Second, the thickness of stainless steel screw coating inspection
1. Gage method: The amount used has a micrometer, a vernier caliper, a plug gauge, and the like.
2. Magnetic method: The magnetic method measures the thickness of the coating layer, which is a non-destructive measurement of the non-magnetic coating layer on the magnetic substrate by a magnetic thickness gauge.
3. Microscopy: The microscopy method is called the metallographic method. It is used to enlarge the etched fasteners on a metallographic microscope with a micrometer eyepiece to measure the thickness of the coating on the section.
4, timing flow method
In fact, the timing flow method uses a solution capable of dissolving the plating solution to be injected on a partial surface of the plating layer, and the thickness of the plating layer is calculated according to the time required for the partial plating layer to dissolve. There are also plating drip method, anode dissolution coulometric method and the like.
Third, the inspection of the adhesion strength of stainless steel screw coating
There are many methods for assessing the adhesion of a coating to a base metal, and there are usually the following.
1. Friction polishing test;
2. Sickle test;
3. Scratch method;
4. Bending test;
5. Thermal shock test;
6, extrusion method.
Fourth, stainless steel screw coating corrosion resistance test
1. Air explosion test;
2. Sexual salt spray test (NSS test);
3. Acid mist test (ASS test);
4. Accelerate the acetate spray test (CASS test);
5. Corrosion corrosion test (CORR test);
6. Liquid drip corrosion test;
7, stain test, inter-dip corrosion test, etc.