How to test stainless steel screws?

Publish time: 25 Jan 22

A. Appearance quality requirements
The appearance inspection of stainless steel screws is carried out from the aspects of appearance, electroplating and so on.

B. Check the screw coating thickness
1. Method of measuring tools for titanium screws: use micrometers, vernier calipers, plug gauges, etc.

2. Magnetic method: The thickness of the coating is measured by the magnetic method, which is a non-destructive measurement of non-magnetic coatings on magnetic substrates using a magnetic thickness gauge.

3. Microscopy: Microscopy is called metallographic method, which is to unfold the etched fasteners on the metallographic microscope with a micrometer eyepiece, and measure the coating thickness of this part.

4. Timed liquid flow mode
The timed liquid flow method uses a solution that dissolves the paint poured onto a portion of the surface of the paint and calculates the thickness of the paint based on the time it takes to dissolve a portion of the paint. There are also drop coating method, anodic dissolution Coulomb method, etc.

C. Inspection of Screw Coating Adhesion
There are generally several ways to evaluate the adhesion between a coating and the base metal.
1. Conflict polishing experiment;
2. Document method experiment;
3. Scratch method;
4. Zigzag experiment;
5. Thermal shock test;
6. Knead.

D. Corrosion Resistance Inspection of Stainless Steel Screw Coatings
Coating corrosion resistance inspection methods include: atmospheric exposure test; neutral salt spray test (NSS test); acetate spray test (ASS test), copper accelerated acetate spray test (CASS test); corrosion paste corrosion test ( CORR test) and solution drop corrosion test; immersion test, interphase corrosion test, etc.