The selection of mold material is a very important part of the whole mold making process.

The selection of mold materials should meet three principles: the mold should meet the working requirements such as wear resistance and toughness, the mold should meet the process requirements, and the mold should meet the economic applicability.

(1) Uniform meets the requirements of working conditions

1、Abrasion resistance

When the plastic deformation of the blank occurs in the mold cavity, it flows on the surface of the cavity and slides on it, causing strong friction between the surface of the cavity and the blank, resulting in the failure of the mold due to wear. Therefore, the wear resistance of the material is one of the most basic and important properties of the mold.

Hardness is the main factor affecting wear resistance. Generally the higher the hardness of the mold part, the lower the wear and the higher the wear resistance. In addition, the wear resistance is also related to the type, number, shape, size and distribution of carbide in the material.

2、Strong strength

The operating conditions of most molds are poor, and some are often subjected to large impact loads, leading to brittle fracture. In order to prevent the mold parts from sudden brittle fracture during operation, the mold must have high strength and impact strength. The strength of the mold mainly depends on the carbon content, grain size and the organizational state of the material.

3、Fatigue failure index

During the operation of the mold, under the action of cyclic stress for a long time, fatigue damage will often occur. Its form includes low energy multiple impact fatigue damage, tensile fatigue damage, contact fatigue damage and bending fatigue damage. The fatigue damage characteristics of the mold mainly depend on its strength, toughness, hardness and inclusions in the material content.

4、Working under high temperature

When the working temperature of the mold is high, the hardness and strength decrease, leading to premature wear or plastic deformation of the mold and failure. Therefore, the mold material must have high tempering resistance to ensure high hardness and mold strength at working temperature.

5、Resistance to hot and cold fatigue

Some molds are in a state of repeated heating and cooling during operation, so that the cavity surface is subject to tension, pressure and stress, resulting in surface cracking and spalling, increased friction, plastic deformation difficulties, and reduced dimensional accuracy. This leads to mold failure. Cold and heat fatigue is one of the main forms of hot processing mold failure, these molds must have a high resistance to cold and heat fatigue performance.

6、Corrosion resistance

When working with some molds such as plastic molds, due to the presence of chlorine, fluorine and other elements in the plastic, the heat will decompose HCI, HF and other strong corrosive gases, corrosion of the mold cavity surface, increase its surface roughness, and intensify wear, stop using.

(2) The shape meets the process performance requirements

Mold production usually goes through several processes such as forging, cutting and heat treatment. In order to ensure the quality of mold manufacturing and reduce production costs, the material must have good ductility, machinability, hardenability, hardenability and grindability, as well as low sensitivity to oxidation, decarburization and hardening, and the tendency to deformation and cracking.

1、Ductility

Low deformation resistance during hot forging, good ductility, wide forging temperature range, low tendency to forging and cold cracking and reticulated carbide precipitation.

2、Annealing technology

Wide range of annealing temperature for spheroidization, low annealing hardness, small fluctuation range, fast spheroidization speed.

3、Machinability

High cutting volume, low tool loss, low surface roughness.

4、Sensitivity to oxidation and decarburization

Good oxidation resistance when heated at high temperature, slow decarburization, insensitive to heating medium, low pitting tendency.

5、Hardenability

After quenching, it has uniform and high surface hardness.

6、Hardenability

After quenching can get deeper hardening layer, can be quenched by mild quenching medium.

7、Tendency to strain cracking during quenching

Ordinary quenching volume change is small, shape deformation, small deformation, low tendency of abnormal deformation. Traditional hardening sensitivity is low (mold material,chongqing meta,imported mold steel)