Have you found the main factors that affect metal rust?


Release time:

2019-12-23

Internal factors of (I) metal corrosion
From a thermodynamic point of view, compared with metal and its corrosion products, it has higher energy and is unstable. It has a tendency to spontaneously convert to low-energy corrosion products, that is, metal corrosion is a natural phenomenon. The vast majority of metals in the industry are multi-component alloys with different metallographic structures, impurities, uneven machining deformation, uneven stress distribution, etc. These physical, chemical and electrochemical inhomogeneities, when the surface encounters Corrosion media or the formation of a water film on the surface, chemical or electrochemical corrosion will inevitably occur.
External factors (II) metal corrosion
1. Relative temperature shadow
The higher the relative humidity in the air, the thicker the water film on the metal surface, and the oxygen in the air passes through the water film to the metal surface. When the relative humidity reaches a certain value, the corrosion rate rises sharply. This value is called critical relative humidity, and the critical relative humidity of steel is about 70%.
2. Effect of temperature
Ambient temperature and relative humidity, dry environment (desert), high temperature metal is not easy to rust. When the relative humidity reaches the critical value, the influence of temperature is obviously intensified, and the corrosion rate increases twice for every 10 ℃ increase in temperature. Therefore, in the wet tropical or rainy season, the higher the temperature, the more serious the corrosion.
3. Effect of oxygen
The rust process is represented by the following reaction:
Fe H2O→Fe(OH)2
Fe(OH)2 H2O O2→Fe(OH)3
Fe H2O O2→Fe(OH)3
It can be seen that without water and oxygen, metal will not rust. 20% of the volume of air is oxygen, which is pervasive.
4. Effects of other substances in the atmosphere
When the atmosphere contains salt spray, sulfur dioxide, hydrogen sulfide and dust, it will accelerate corrosion. Therefore, the difference in the size of corrosion in different environments is obvious, with cities being higher than rural areas; industrial areas are higher than living areas; coastal areas are higher than inland; High dust is higher than low dust.
Rust factors in (III) processing














The raw material has been rusted and cannot be removed after processing. Contact with cutting fluid, lubricant and other process materials during processing; Improper neutralization and cleaning after pickling; Heat treatment oxidation decarburization or residual salt cleaning is not clean; Hand sweat left by the operator during inspection, handling and assembly; Improper de-stress or de-hydrogen annealing; It is not suitable for inter-process and sealing to prevent rust.
What if the metal rusts? It is recommended to use Resbo'sRSB-501 neutral rust removerIt only reacts with rust, not with metal. No need for water washing, improve efficiency.