（1） The mold meets the requirements of working conditions

1. Wear resistance

When the billet undergoes plastic deformation in the mold cavity, it flows and slides along the surface of the cavity, causing severe friction between the cavity surface and the billet, leading to the failure of the mold due to wear. So the wear resistance of the material One of the most basic and important properties of a mold.

Hardness is the main factor affecting wear resistance. In general, the higher the hardness of mold parts, the smaller the wear amount, and the better their wear resistance. In addition, wear resistance is also related to the type, quantity, morphology, size, and distribution of carbides in the material.

2. Strong resilience

The working conditions of molds are mostly very harsh, some of which often bear large impact loads, leading to brittle fracture. To prevent sudden brittle fracture of mold parts during operation, molds should have high strength and toughness.

The toughness of the mold mainly depends on the carbon content, grain size, and microstructure of the material.

3. Fatigue fracture performance

During the working process of the mold, long-term cyclic stress often leads to fatigue fracture. Its forms include small energy multiple impact fatigue fracture, tensile fatigue fracture, contact fatigue fracture, and bending fatigue fracture.

The fatigue fracture performance of a mold mainly depends on its strength, toughness, hardness, and the content of inclusions in the material.

4. High temperature performance

When the working temperature of the mold is high, it will cause a decrease in hardness and strength, leading to early wear or plastic deformation of the mold and failure. Therefore, the mold material should have high tempering stability to ensure that the mold has high hardness and strength at working temperature.

5. Cold and hot fatigue resistance

Some molds are in a state of repeated heating and cooling during the working process, causing the surface of the mold cavity to be subjected to tensile and compressive stress, causing surface cracking and peeling, increasing friction, hindering plastic deformation, reducing dimensional accuracy, and ultimately leading to mold failure. Cold and hot fatigue is one of the main forms of failure in hot working molds, and such molds should have high resistance to cold and hot fatigue.

6. Corrosion resistance

Some molds, such as plastic molds, when working, due to the presence of elements such as chlorine and fluorine in the plastic, they decompose and release strong corrosive gases such as HCI and HF after being heated, eroding the surface of the mold cavity, increasing its surface roughness, and exacerbating wear and failure.

（2） The mold meets the process performance requirements

The manufacturing of molds generally involves several processes such as forging, cutting, and heat treatment. To ensure the manufacturing quality of the mold and reduce production costs, the material should have good malleability, machinability, hardenability, hardenability, and grindability; It should also have a small sensitivity to oxidation, decarburization, and a tendency towards quenching deformation and cracking.

1. Malleability

It has low resistance to hot forging deformation, good plasticity, wide forging temperature range, low tendency for cold cracking and precipitation of network carbides during forging.

2. Annealing process

Spheroidization annealing has a wide temperature range, low annealing hardness and small fluctuation range, and high spheroidization rate.

3. Machinability

The cutting amount is large, the tool loss is low, and the machined surface roughness is low.

4. Sensitivity to oxidation and decarbonization

When heated at high temperatures, it has good antioxidant capacity, slow decarbonization speed, is not sensitive to the heating medium, and has a small tendency to produce pitting.

5. Hardenability

After quenching, it has a uniform and high surface hardness.

6. Hardenability

After quenching, a deeper hardening layer can be obtained, and quenching can be achieved using a mild quenching medium.

7. Quenching deformation and cracking tendency

Conventional quenching has small volume changes, slight shape warping and distortion, and low tendency for abnormal deformation. Conventional quenching has low sensitivity to cracking and is not sensitive to quenching temperature and workpiece shape.

8. Grindability

The grinding wheel has relatively low wear and tear, and the maximum grinding amount without burns is large. It is not sensitive to the quality and cooling conditions of the grinding wheel, and is less prone to grinding injuries and cracks.

（3） Mold meets economic requirements

When selecting materials for molds, the principle of economy must be considered to minimize manufacturing costs as much as possible. Therefore, on the premise of meeting the performance requirements, the first choice is to use lower priced materials, such as carbon steel instead of alloy steel, and domestic materials instead of imported materials. In addition, when selecting materials, consideration should also be given to the production and supply situation in the market, and the selected steel grades should be as few and concentrated as possible, making it easy to purchase.