The most obvious way is to differentiate by color:
Stainless steel is the original color of iron. Galvanized screws are white, colored or black. Nickel-plated screws are silver.
Stainless steel screws are made of stainless steel. The color of stainless steel is mainly an alloy of iron and carbon, so the color is close to that of iron;
Galvanized screws have white zinc, colored zinc or black zinc on their surface. Therefore, the color of galvanized screws is generally white, colored or black;
The color of nickel-plated screws is related to nickel. Generally, it presents a very bright silver color.
To distinguish them through tests:
Using a magnet: Stainless steel generally does not have magnetism and cannot be attracted by a magnet. Those that cannot be attracted by a magnet are stainless steel screws. Galvanized and nickel-plated screws can be attracted by a magnet.
Using an oxidizing agent: Metal nickel has a strong anti-corrosion ability. During electroplating, a very thin layer of passivation can be rapidly formed on the surface. Therefore, the surface of nickel-plated screws has a passivation film, while the surface of galvanized screws is a layer of zinc, and the surface of stainless steel has nothing. Strong oxidizing agents can be used to distinguish.
Using strong acids and strong bases: Stainless steel contains chromium and nickel, has strong anti-corrosion properties, and is not corroded by strong acids and strong bases. Nickel-plated screws have a layer of passivation on the surface, and are corroded more slowly than galvanized screws. Galvanized screws are corroded the fastest.
Hot-dip galvanized screws have the following advantages:
Low processing cost: The cost of hot-dip galvanizing for rust prevention is lower than that of other paint coatings;
Long-lasting and durable: In suburban environments, the standard thickness of hot-dip galvanizing rust prevention can remain for more than 50 years without repair; in urban or coastal areas, the standard hot-dip galvanizing rust prevention layer can remain for 20 years without repair;
High reliability: The galvanized layer is metallurgically combined with the steel and becomes part of the steel surface, so the durability of the coating is relatively reliable;
Strong toughness of the coating: The galvanized layer forms a special metallurgical structure, which can withstand mechanical damage during transportation and use;
Comprehensive protection: Every part of the plated part can be plated with zinc, even in recesses, corners and hidden areas, it can be fully protected;
Time-saving and labor-saving: The galvanizing process is faster than other coating construction methods, and it can avoid the time required for painting on the construction site after installation.
The application scope of galvanized screws is wider than that of stainless steel screws, and the usage quantity is also greater. However, it should be noted that: Galvanized screws cannot completely replace stainless steel screws. In terms of corrosion resistance, it will eventually be inferior to stainless steel screws. In addition, nickel plating is generally more expensive than galvanizing. Therefore, it is still necessary to select the appropriate material according to the usage occasion.
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