Appearance inspection: Silicon-containing spring steel is reddish brown, other spring steel is black, oxide film should be uniform and dense, there should be no spots, surface fading or red and dark deposits. Corrosion resistance test: Wash the surface with alcohol or gasoline, soak it in 2% copper sulfate solution for 30s, remove it and wash it in water, there should be no red spots on the surface.
The appearance of the phosphating film should be uniform, no flowering, the surface is gray or dark red, and the corrosion resistance test can be checked in the following two ways.
(1) The composition of the test solution by the copper sulfate solution is as follows:
0.5NCuSO4 solution 40ml
10% NaCl solution 20ml
0.1HCL solution 0.8ml
After mixing the three kinds of solutions, the surface of the spring washed with alcohol was dripped, and the time of red spots was recorded. The normal phosphating film was maintained for at least 1 min.
(2) Soaking method of salt water: soak the phosphatized spring in 3% salt solution for 15 minutes, remove it, rinse it with water, place it in the air and dry it for 30 minutes, no yellow rust, it is qualified.
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