(a) meet the requirements of working conditions

1. Resistance to wear

Blank plastic changes in the mold cavity, the cavity surface flow and sliding surface of cavity and a dramatic friction between billet, resulting in mould failure due to wear and tear. So the wear resistance of materials is the most basic, one of the most important performance of mould.

Hardness is the main factors influencing the abrasion resistance. In general, the higher hardness of mould parts, the wear quantity is smaller, the resistance to wear. In addition, resistance to wear and material of carbide in species, quantity, shape, size and distribution.

2. Strong toughness

Die working conditions are very bad, some often bear a larger impact load, which can lead to brittle fracture. Suddenly brittle fracture at work to prevent the mold parts, mold with high strength and toughness.

Mould toughness mainly depends on the materials of carbon content, grain size and organization.

3. The fatigue fracture properties

Die working process, under the action of a cyclic stress in the long term, often leads to fatigue fracture. The form there is little energy repeated impact fatigue fracture and tensile fatigue fracture contact fatigue fracture and fatigue fracture.

Fatigue fracture properties of mold mainly depends on the strength, toughness, hardness, and the content of inclusions in the material.

4. The high temperature performance

When the mould into the working temperature is higher, can make the hardness and strength drop, cause mould early wear or produce plastic deformation and failure. As a result, the mould material should have high resistance to tempering stability, to ensure that the mold in the working temperature, has high hardness and strength.

5. Cold and hot fatigue resistance

Some mold in the process of the work is in a state of repeated heating and cooling, make the cavity surface tension, pressure, stress, surface crack and spalling, caused by increased friction, obstacles to plastic deformation, reduces the dimension precision, which can lead to mold failure. Cold and hot fatigue is one of the main form for the failure of hot-work die, help the mold should have higher resistance to cold and hot fatigue performance.

6. The corrosion resistance

Some mould such as plastic die on the job, as a result of plastic, such as chlorine, fluorine element in thermal decomposition after precipitation HCI, HF gas strong erosion, erosion of the mold cavity surface, increase the surface roughness, and wear failure.

(2) satisfies the requirement of process performance

Mould manufacturing is typically after forging, machining, heat treatment and so on several process. In order to ensure the manufacturing quality of mould, reduce production cost, the materials should have good forgeability, cutting processability, hardenability, hardenability and grinding; Also should have little oxidation and decarburization sensitivity quenching distortion and cracking tendency.

1. The malleability

Have relatively low hot forging deformation resistance, good plasticity, forging temperature range wide, cold forging crack crack and precipitation carbide network tend to be low.

2. The annealing process

The spheroidizing annealing temperature range wide, annealing hardness is low and the fluctuation range is small, spheroidization rate is high.

3. The cutting process

Low cutting parameter, cutting tool wear, machining surface roughness is low.

4. The oxidation and decarbonization sensibility

When heated to high temperature oxidation resistance with good, decarburization speed slow, is not sensitive to the heating medium, to produce pitting tend to be small.

5. Hardenability

A uniform and high surface hardness after quenching.

6. H

After quenching can get deeper hardening layer, using moderate quenching medium can be hardened.

7. Quenching distortion cracking tendency

Conventional quenching small volume change, shape warping, distortion, mild, abnormal deformation tend to be low. Conventional quenching cracking sensitivity is low, is not sensitive to the quenching temperature and shape of the workpiece.

8. Grinding can be

Limit dosage of grinding wheel relatively small loss, no burns, the quality of grinding wheel and cooling conditions is not sensitive, grinding and grinding cracks is not easy to occur.

(3) meet the requirements of economical efficiency

Economy must be taken into account in to the mold material is, the principle, as much as possible to reduce the manufacturing cost. In meet the under the premise of using performance, therefore, first of all, choose low price, can use carbon steel don't have to alloy steel, can use domestic material don't have imported material.

In addition, should also be considered when selecting the production and supply of the market, the selected material should be as little as possible and concentrated, easy to buy.