Cause of wear of machine parts

The main cause of wear of machine parts is that alloy parts made of ferrous metal (steel and cast iron) are not suitable for manufacturing mechanical parts, especially friction parts. Because:

1. alloy belongs to chemical unstable material

Steel is a solid solution of many elements. These elements cause chemical instability in the production process, and this solid solution is poorly mixed. You will get this conclusion if you want to get chemical composition analysis at every point or on the length of the bar. On the one hand, additives and fluxes make the steel necessary. On the other hand, it is the source of the internal stress at the level of crystallography and the source of the most harmful inclusions in the chemical. These impurities are first chemically reacted with the elements around them. I have not said that a large number of hydrogen atoms in these solid solutions will lead to hydrogen induced cracking on the friction surface. Hydrogen has been dissolved in ferrous metals in blast furnaces and converters.

2. undergo electrochemical corrosion

Careful observation shows that the relative movement of mechanical parts occurs at work, that the shaft rotates at different speeds or that one of the friction pairs is immovable. This causes different potentials on the friction surface of the parts, producing electric field at the contact points, and the rate of chemical reaction on the friction surface is increasing rapidly. Lubricating oil that is added to machinery to prevent wear is the transfer factor of these reaction products. It should be added that the more serious situation is that the chemical composition of the friction contact surface is different, and there is a micro electric field between the iron and the composition of the molten steel and the crystal of the flux on the friction surface. Another is the damage caused by hydrogen induced cracks. Electrochemical corrosion causes loose structure on the friction surface and loses its original strength, which further aggravates the speed of electrochemical reaction. So far, people still use ferrous metal to make mechanical parts, which can not avoid the occurrence of electrochemical corrosion.

The most obvious example of the destruction caused by electrochemical reaction is the wear of the steel journal at its contact with the seal.

The weight of the 3. parts is relatively large

In order to obtain a considerable structural strength and a certain insurance factor, the physical and mechanical properties of most ferrous metal species require a large amount of metal. This causes the loss of the carrier at startup. The difference between the amount of fuel consumed in the city and the highway indicates this problem.

4. can't "dry" friction

Abrasions, tempering and all kinds of damage occur quickly in the weld metal. Therefore, the structure made of ferrous metal requires the addition of lubricating materials to separate and cool the friction surfaces. Lubricating oil is supplied by special oil circuit system, making the mechanical structure more complex and more cumbersome.

5. the processing technology of black metal is complex

We only talked about the extensive application of metal turning and grinding. Because in most cases the parts are finished after the completion of these processes, it is also because we are interested in the surface state of these parts (in the future contact with similar surfaces). Notice that the turning process can only be seen as a chip. Behind the lathe tool, we saw a large number of cutting surfaces with a lot of fracture traces perpendicular to the tool stroke. These micro cracks will only expand and deepen in the future. Of course, the situation behind the lathe tool is different, for example, how about the sharpening of the lathe tool? What type of lathe tool is it? What kind of metal is it? Finally, how about the clearance between spindle bearings of machine tools? On the whole, the surface was damaged. The damage of grinding to the working surface of parts is much the same. What I want to say is that the most widely used metal processing technology, turning and grinding, destroys the working surfaces of parts and accelerates their wear and tear in the future. There's a human factor here. In fact, not all workers can avoid sharp turning tools and sharpening tools when turning.

These conditions have been formed for a long time. We have little relationship with us. People have been looking for a solution, but the suitable substitute materials for black metals have not been found yet.