（1）Meet the requirements of working conditions
1. Wear resistance
When the blank is plastically denatured in the mold cavity, it flows and slides along the cavity surface, resulting in severe friction between the cavity surface and the blank, resulting in the failure of the mold due to wear. Therefore, the wear resistance of materials is one of the most basic and important properties of molds.
Hardness is the main factor affecting wear resistance. In general, the higher the hardness of die parts, the smaller the wear, and the better the wear resistance. In addition, the wear resistance is also related to the type, quantity, shape, size and distribution of carbides in the material.
2. Strength and toughness
The working conditions of molds are mostly very bad, and some often bear large impact load, resulting in brittle fracture. In order to prevent sudden brittle fracture of die parts during operation, the die should have high strength and toughness. The toughness of the die mainly depends on the carbon content, grain size and microstructure of the material
3. Fatigue fracture performance
In the process of die working, fatigue fracture is often caused by the long-term action of cyclic stress. Its forms include small energy multiple impact fatigue fracture, tensile fatigue fracture, contact fatigue fracture and bending fatigue fracture. The fatigue fracture performance of the die 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 die is high, the hardness and strength will decrease, resulting in early wear or plastic deformation and failure of the die. Therefore, the die material should have high tempering stability to ensure that the die has high hardness and strength at working temperature.
5. Cold and hot fatigue resistance
Some molds are in the state of repeated heating and cooling in the working process, so that the surface of the cavity is under the action of tensile and pressure strain stress, resulting in surface cracking and peeling, increasing friction, hindering plastic deformation and reducing dimensional accuracy, resulting in mold failure. Cold and hot fatigue is one of the main forms of hot working die failure. This kind of die should have high cold and hot fatigue resistance.
6. Corrosion resistance
When some molds such as plastic molds are working, due to the presence of chlorine, fluorine and other elements in the plastic, they decompose and precipitate strong corrosive gases such as HCI and HF after heating, which erode the surface of the mold cavity, increase its surface roughness and aggravate wear failure.
（2） Meet the process performance requirements
The manufacture of molds generally goes through several processes such as forging, cutting and heat treatment. In order to ensure the manufacturing quality of the die and reduce the production cost, the material should have good malleability, machinability, hardenability, hardenability and grindability; It should also have small oxidation, decarburization sensitivity and quenching deformation cracking tendency.
1. Malleability
It has low hot forging deformation resistance, good plasticity, wide forging temperature range, low tendency of forging crack, cold crack and precipitation of network carbide.
2. Annealing process
The spheroidizing annealing temperature range is wide, the annealing hardness is low and the fluctuation range is small, and the spheroidizing rate is high.
3. Machinability
Large cutting parameters, low tool loss and low machining surface roughness.
4. Oxidation and decarburization sensitivity
When heated at high temperature, it has good oxidation resistance, slow decarburization speed, insensitive to heating medium and small tendency to produce pitting.
5. Hardenability
After quenching, it has uniform and high surface hardness.
6. Hardenability
After quenching, a deep hardening layer can be obtained, and it can be hardened with mild quenching medium.
7. Quenching deformation and cracking tendency
Conventional quenching has small volume change, slight shape warpage and distortion, and low tendency of abnormal deformation. Conventional quenching has low cracking sensitivity and is not sensitive to quenching temperature and workpiece shape.
8. Grindability
The grinding wheel has small relative loss, no burn limit, large grinding amount, insensitive to grinding wheel quality and cooling conditions, and is not prone to abrasion and grinding cracks.
For more technical questions, you can consult Chapman Maker team and provide professional technical support.
Sales Email: info@chapmanmaker.com
Post time: May-03-2022