Application of liquid die forging for large wear-resistant plate

Large wear-resistant plate is a kind of wear-resistant steel parts, the amount of which is second only to grinding. Among the large-scale wear-resistant plate parts, the consumption of iron mill lining is the largest. Other categories mainly include metal hot rolling mill guide plate, impact hammer, rotary crusher lining plate, jaw crusher jaw plate, CIS crusher leading plate, cone crusher crushing wall, vertical impact hammer head, etc., which are usually used in building materials, coal, electricity, metallurgy, construction, transportation and other fields Under the condition of material wear, more Abrasives wear and strong impact, so it becomes an irreplaceable “victim” under these conditions.

The shape and weight of wear-resistant plate parts vary from kilogram to kiloton. At present, the research of wear-resistant white cast iron, austenitic wear-resistant steel and composite wear-resistant materials has been relatively mature, among which high chromium cast iron and high manganese steel are widely used as wear-resistant plate materials. However, contrary to the development of materials, the main production process of wear-resistant plate is still sand casting. As a traditional process, it has the advantages of low cost, short mold manufacturing cycle and wide process adaptability. It can be used in large and small batches of complex and simple parts, large and small parts. However, for the production of large-scale wear-resistant plate, the disadvantages and limitations of sand casting are more significant: because each time the casting is obtained, the sand mold is damaged and can only be reshaped, resulting in the low efficiency of sand casting in production. In addition, due to the low rigidity of the mold, the poor dimensional accuracy of the casting, and easy to produce sand punching, sand inclusion, porosity and other defects, the above limitations undoubtedly have a great negative effect on the production of large wear-resistant plate and the quality of the workpiece. In addition to sand casting, there are also people who use overlay welding, explosive welding, rolling and other methods to produce metal composite wear-resistant plate, but there are many disadvantages, such as low productivity, difficult to control welding deformation, high cost and so on. Therefore, to improve the forming process is another effective way to improve the product quality, life and economic benefits.

At present, the liquid forging technology has made a great breakthrough. It is a kind of metal forming process that the liquid metal is directly poured into the metal mold cavity, the liquid metal flows and fills the mold after the mold is closed, at the same time, under the action of mechanical static pressure, solidification under high pressure and a certain amount of plastic deformation occur, and finally the qualified workpiece or blank is produced. At present, the development of wear-resistant steel parts industry is more and more strict with the product conditions,

It requires not only high wear resistance and service life, but also excellent corrosion resistance and fatigue performance. Limited by the principle of traditional technology, it is difficult to meet the above requirements, and liquid forging can solve these pain points in principle, so as to improve the wear resistance of workpiece. As the production process of wear-resistant plate, the advantages of liquid die forging are as follows:

① Before solidification, the liquid metal is always under the action of isostatic pressure. Crystallization and solidification under pressure can obtain more compact structure. Not only that, but also plastic deformation can occur under pressure after solidification. The hot deformation structure with fine grains and uniform structure can be obtained, and the effect is similar to forging;

② Liquid die forging is realized by special liquid forging machine, which is more close to the industrial environment of automation and mechanization. It can reduce the labor intensity of operators to a certain extent, promote the improvement of production environment, and obtain higher production efficiency;

③ In the process of liquid forging, isostatic pressure can force the workpiece to close to the die cavity to make its size and shape accurate;

④ There are basically no defects such as shrinkage cavity, shrinkage porosity and porosity in the liquid forging, and the mechanical properties of the product can be guaranteed;

⑤ The mechanical properties of liquid forgings can be significantly higher than that of ordinary castings, and close to or even equal to that of forgings of the same component metal, but there is no anisotropy in forgings;

⑥ The liquid forging process has high yield, little environmental pollution, no solid waste discharge and recycling of riser and molding sand, no dust casting, and meets the new requirements of “green casting”. According to the literature, the yield strength of liquid forging can be increased by 10% – 15% than that of die casting, and the fatigue strength and elongation can be increased to 50% – 80%.

From the principle analysis, using the liquid die forging process to produce wear-resistant steel plate parts will achieve better results in product performance, process yield and other aspects, but the application of liquid die forging in large wear-resistant steel plate parts also has its difficulties. Although in recent years, with the localization of liquid forging machine, the improvement of the service life of liquid forging die and the development of liquid forging coating, the research and industrial application of liquid forging in the field of ferrous metals have made gratifying progress, most of them are mainly concentrated in small and medium-sized parts with weight less than tens of kilograms and length less than one meter, such as steel groove wheel, steel flange, roll and roll sleeve, brake disc, etc For large wear-resistant plate parts with a weight of 100 kg and a length of more than one meter, the difficulties of liquid die forging can be summarized as follows:

① Because of the large cross-sectional area of the large-scale parts, the tonnage of the equipment required by the traditional liquid forging and pressing method is very large;

② Large casting amount, especially multi cavity indirect liquid forging, is easy to cause many defects, such as cold insulation, oxidation and so on;

③ For the production of large-scale steel parts, the requirements of liquid forging die are very high, and the life of die is worrying;

④ For liquid forging of iron and steel parts, the current process and die design is still empirical design, and the empirical data of non-ferrous metal liquid forging is not fully applicable, which seriously limits the pace of industrial application.

The above problems lead to the application of liquid forging in large steel parts is still almost blank. Therefore, it is of great significance to study the liquid die forging process and the structure and properties of large wear-resistant plate.