How to prevent fasteners from getting rusty

In the fastener industry, the screw and nut play a role in connecting and fixing in various industries. Many fasteners used outdoors, such as bridges and nuts in the guardrail, are exposed to the sun and rain for a long time. Even worse, the sea is more likely to rust. The rusted screws not only affect the appearance but also pose a safety hazard. Then let me talk about why the screws will rust? What kind of screws are not easy to rust? How to improve the screw performance of fasteners?
The Principle of Fastener Rust
Metal fasteners come into contact with chemical components in moist air during prolonged use. A chemical change has occurred - electrochemical corrosion. This type of corrosion is also the most common. It is also a problem often encountered with fasteners.

There are many principles for the corrosion of metals, of which electrochemical corrosion is the most extensive. When the metal is placed in an aqueous solution or a humid environment, the metal surface forms a microbattery, also known as Electrochemical corrosion.

An oxidation reaction occurs on the anode to dissolve the anode, and a reduction reaction occurs on the cathode, generally only functioning to transfer electrons. Corrosion cells are mainly formed because the metal surface adsorbs moisture in the air to form a water film. This water film contains a small number of hydrogen ions and hydroxide ions and also dissolves oxygen and other gases. An electrolyte solution is formed which forms a myriad of tiny primary cells with iron and a small amount of carbon in the steel.

In these primary batteries, iron is the negative electrode and carbon is the positive electrode. Iron loses electrons and is oxidized. Electrochemical corrosion is the main cause of corrosion
Type of Corrosion
Galvanic Corrosion
Galvanic corrosion is a common type of corrosion. Galvanic corrosion is the combination of two electrodes, metal, and electrolyte, which constitute a corrosive primary battery. For example, iron and oxygen, because the electrode potential of iron is always lower than the electrode potential of oxygen, so iron is the negative electrode and is corroded. It is characterized by the formation of many small drums of different diameters on the surface where oxygen corrosion occurs, and the second layer is a black powdery ulcer corrosion pit.

Pitting Corrosion
Pitting corrosion is a very localized corrosion form of a metal surface forming a small hole in a corrosive medium, Pitting is one of the most destructive types of corrosion. Corrosive pores exist in isolation and some are compact together. Pitting corrosion causes the metal to lose weight very little, but can cause perforation damage.

Pitting corrosion is a unique form of anodic reaction in electrochemical reactions. If the metal is passive in this medium, the active anions (such as chloride ions) contained in the medium can be selectively and selectively adsorbed on the passivation film at specific points (such as defects and impurities). A compound that combines with a cation in the passivation film to form a soluble substance, where a small corrosion point occurs and becomes a pitting nucleus (about 20 to 30 pm). Continue to develop can become an etch hole. This corrosion is dangerous because it can cause the entire structure to fail.

Crevice Corrosion
Crevice corrosion refers to localized corrosion that occurs in cracks and other concealed areas on metal surfaces in corrosive media. Holes, gasket contact surfaces, lap joints, under deposits, and fastener gaps are places where crevice corrosion often occurs. Metals that are resistant to corrosion by oxide or passivation layers are particularly susceptible to corrosion. Crevice corrosion occurs in many media, especially in oxygen-containing media. Crevice corrosion is also an electrochemical corrosion

Intergranular Corrosion
Intergranular corrosion is a type of localized corrosion. Corrosion that extends toward the interior along with the interface between the metal grains. Mainly due to the difference in chemical composition between the surface and the interior of the grain and the presence of grain boundary impurities or internal stress. Intergranular corrosion destroys the bond between the grains, greatly reducing the mechanical strength of the metal. Moreover, the surface of the metal and alloy still maintains a certain metallic luster after the corrosion occurs, and there is no sign of damage, but the intergranular bonding force is significantly weakened, the mechanical properties are deteriorated, and it cannot withstand tapping, so it is very dangerous corrosion. Usually found in brass, hard aluminum alloys, and some stainless steel, nickel-based alloys

Stress Corrosion Cracking (SCC)
Stress Corrosion Cracking (SCC) is the result of cracking caused by the interaction of materials or parts under stress and corrosive environments, usually at elevated temperatures. Stress corrosion can be caused by external stresses. The cracking caused by the joint action of materials or parts under stress and the corrosive environment is called stress corrosion cracking, which is the result of the combination of stress and corrosion. SCC has a variety of reasons, including stresses caused by cold working, welding and heat treatment. These factors, combined with exposure to environments that frequently increase and exacerbate stress cracking, may mean that some suffer from minor stress corrosion to failure or irreparable damage. If there is only one aspect, the effect of stress or medium, the damage will not occur, but when the two work together, they can crack quickly. Therefore, when stress corrosion occurs, the stress is very low, and the corrosiveness of the medium is also very weak. Because of this, stress corrosion is often neglected, resulting in "accidental" accidents.
How To Prevent Fastener Corrosion
Corrosion Resistant Material
Many metal materials are corrosion resistant.  Metals such as aluminum, copper, and titanium have corrosion resistance. The properties of these metals can be utilized to make the corresponding fasteners. Corrosion protection can be achieved.

Protective Coating
A layer of paint is added to the outer surface of the fastener, and paint is used to isolate the fastener from air contact. Thereby reaching the purpose of preventing corrosion.

Electroplating is the process of plating a thin layer of other metals or alloys on some metal surfaces by electrolysis. It is a process of attaching a metal film to the surface of metal or other materials by electrolysis to prevent metal oxidation ( Such as rust), improve wear resistance, electrical conductivity, light reflectivity, corrosion resistance (copper sulfate, etc.).

Corrosion Inhibitor
Corrosion inhibitors are chemicals that react with gases on the surface of fasteners or in the air. Forming a protective film on the surface of the fastener to protect the fastener from corrosion

Environmental Control
1, the screw should be placed in a suitable environment, should not be too wet, should be ventilated, ventilated, there should not be too much water vapor, there should be shelves to put the screws up, not in contact with the ground.
2. When electroplating is done in the electroplating factory, try not to have moisture remaining.
3. Select the type of plating with long salt spray time, and plate it to a certain thickness according to the standard requirements. For example, the zinc layer is generally required to be around 6-8mμ.
4, to prevent long-term use in the environment of humidity, salinity, acidity, saltiness, high corrosion, high temperature, high humidity.
Anti-corrosion Fastener Supplier
We are the best anti-corrosion fastener supplier in China. Here you can purchase a wide range of fasteners. such as:
Chipboard Screws
Self Drilling Screws
Self Tapping Screws
Wood Screws
Machine Screw
Decking Clips
Also available in different materials, stainless steel, copper, aluminum, titanium, alloys, etc.
Please tell us your needs, we will give you the best offer!
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