Mechanical processing metal material corrosion and protective measures

The concept of corrosion of metals

The metal material is damaged by the surrounding medium, called Metallic Corrosion. Corrosion of metals is the most common form of corrosion. During corrosion, a chemical or electrochemical multiphase reaction occurs at the interface of the metal, causing the metal to transition to an oxidized (ion) state. This will significantly reduce the mechanical properties of metal materials such as strength, plasticity and toughness, destroy the geometry of metal components, increase wear between parts, deteriorate physical properties such as electrical and optical, shorten the High quality guide rings for excavators supplier in China service life of equipment, and even cause disasters such as fires and explosions. Sexual accidents. In 1975, the economic loss caused by metal corrosion in the United States was 70 billion US dollars, accounting for 4.2% of the GDP of the year. According to statistics, the annual steel loss due to metal corrosion accounts for about 10 to 20% of the steel output of the year. Indirect losses caused by accidents such as production shutdowns and power outages are even more incalculable. Metal corrosion is very common. Such as rusty iron products (Fe2O3·xH2O), white spots (Al2O3) on the surface of aluminum products, copper green [Cu2(OH)2CO3] on the surface of copper products, blackening of silverware surfaces (Ag2S, Ag2O), etc. are all metal corrosion, including Corrosion is the most common metal—iron products.

Metal materials are one of the key materials in modern production. However, due to multiple factors such as the environment, metal materials are prone to different degrees of corrosion during mechanical processing.

Metal materials perform better in terms of strength, stiffness, etc., but corrosion phenomena are more common, which can adversely affect parts in a certain area or even the entire system. Therefore, it is significant to do anti-corrosion work in a reasonable way, which is an important way to extend the life of equipment.

Metal composite materials in machinery manufacturing

Metal composite materials are based on various types of metal materials and are obtained after metallurgy and other processes. Compared with conventional metal materials, this type of material performs better in terms of strength and wear resistance.

Formation and type of corrosion

All kinds of materials will approach a low energy state and maintain stability. Metals are mainly achieved through the way of metal oxides, especially various precious metals represented by gold and silver. The role of such materials in the natural environment The state of oxides has been maintained, and metals must be extracted from them in a very complicated way. When the metal returns to the "unclean" state against the will, corrosion occurs. From the perspective of the type of corrosion, there are mainly two types of chemical corrosion and electrochemical corrosion. According to the phenomenon of corrosion, it can be divided into uniform corrosion and local corrosion of the material somewhere. The inducing factors of corrosion are intricate. For cutting technicians, among the various types of corrosion, the most common is surface corrosion due to rust; in various types of mechanical processing equipment, electrochemical corrosion is dominant.

Causes of corrosion

Among the causes of corrosion of metal materials, the most critical is electrochemical stability. If the potential value is negative, the stability of the material is low. The greater the negative value, the stronger the instability. The metal Ionization is more obvious, leading to significant corrosion of the material [3]. In addition, the internal components of the metal alloy will also affect the quality of the material. Unlike the single alloy material, the probability of corrosion of multiple alloys is relatively higher, because the physical and chemical properties of each item are more obviously different. The potential generated after reaching the electrolyte is also different. For example, under the effect of heat treatment, a variety of metallographic structures will appear in the material. After quenching, the various structures are evenly arranged. This stage has strong corrosion resistance; but after entering the tempering stage, the carbon in the process The amount of precipitation of the precipitated phase of the substance increases significantly, which leads to a significant decline in the corrosion resistance of the material. If the metal surface lacks flatness, the probability of corrosion will increase significantly at this time. Moreover, the metal will be in a more extreme cold or heated environment during the processing stage. For non-oxidizing acid salts, substances of this nature will be more likely to affect the stability of the metal material and cause significant corrosion. This phenomenon is significantly more than in alkaline salt environment.

Corrosion protection

There are many ways for parts to be corroded. Corrosion is easy to occur if the protection is not proper during processing and storage. In view of this feature, it is necessary to protect it in a reasonable way to minimize the corrosion of metal materials.

Corrosion protection during cutting

Obviously, there is a high probability of metal corrosion in a humid air environment, so after completely isolating the two, it can have an anti-corrosion effect, but from the actual situation, the production does not have the conditions to completely isolate the humid air, it is more appropriate The main ways to limit corrosion are as follows: (1) Internal protection: Incorporation of alloy elements with better corrosion resistance improves the corrosion resistance of the metal material itself. (2) External protection: The outer periphery of the material is protected by painting and adding metal coating to make the material isolated from the air.

Corrosion protection measures

For the bare parts of the machine tool, it can be treated by painting. If there are defects in the protective layer during subsequent use, they must be filled in time. If the protective agent and the cooling lubricating fluid do not have compatibility, the two will also corrode when they are in contact, so it is necessary to change the state of the two in a reasonable way to achieve a compatible effect. The cutting process is accompanied by obvious disturbance, which causes damage to the original protective layer, and the workpiece obtained after processing is also prone to corrosion. In this regard, the proper amount of corrosion inhibitors mixed in the cooling lubricant is to produce a dense passivation film, but we must pay attention to the control of the emulsion concentration and adjust it to the optimal range. After processing, the workpiece can be painted or soaked to form a complete protective layer on the surface of the workpiece. In addition, after processing, paraffin can also be used to achieve antiseptic effects.

In short, the comprehensive use of metal materials has a good effect and is widely used in the machinery manufacturing industry. However, metal materials are easily affected by factors such as temperature and acidity and alkalinity, resulting in different degrees of corrosion, which is not conducive to the normal use of materials. In the manufacturing process, it is necessary to protect metal materials through various means to improve their corrosion resistance.