What are the materials commonly used in mechanical systems?

Hehe, it's hard to get cold feet. It's better to read more books on basic mechanical knowledge at ordinary times.

Now I will answer some of your questions.

What is the material?

There are too many materials. For steel parts without special requirements, Q235 and 45 # steel are generally used. For wear resistance, GGr 15 and ZGMn 13 can even be put on ductile iron; For hardness, there are 35CrMo, Cr12mov; ; Stainless steel has 20 1, 304, 3 16 and so on.

These are commonly used steel parts, and there are other materials such as PU (polyurethane), POM (polyoxymethylene), aluminum alloy 606 1, silicon nitride Si3N4, etc.

How to express it?

Just describe the basic characteristics of the material, such as Cr 12MoV, which has good hardenability, small deformation, high hardness after quenching and good wear resistance, and is often used in stamping dies; For another example, the delivery hardness of 3CrMo material is high, which can be achieved without heat treatment, without thermal deformation and good machinability, and is often used in injection molds.

How to deal with it?

Treatment is nothing more than heat treatment and surface treatment. Heat treatment includes quenching, tempering, normalizing and annealing. Generally speaking, it refers to quenching when the hardness increases (note that some materials such as Q235 cannot be quenched) to prevent tempering when cracking and annealing when the hardness decreases.

What role does surface treatment play? Anti-rust functions include painting, plastic spraying, chromium plating and nickel plating, and aluminum alloy can also be anodized. Polishing is used to increase smoothness; Sandblasting and phosphating can increase surface adhesion.

I almost forgot that there is also an aging treatment, which is to remove the internal stress of the material.

Having said that, I hope you can use some tomorrow.

Finally, I wish you a successful interview!