Large heavy forgings generally refer to large heavy forgings with large size and large weight per piece forged on large forging equipment, mainly large free forgings. In the heavy machinery manufacturing industry, the large forgings forged on the hydraulic press above 1000 kn or hammer head above 5t are usually called large heavy forgings.

At present, the weight of single piece of large heavy forgings has reached 250 tons, and the weight of large forging ingots reaches 600 tons.

Large heavy forgings are mostly key components of various large machinery and equipment, such as turbine rotor, generator guard ring, turbine spindle, pipe plate, nuclear power plant with head, etc.. Metallurgical mill rolls: reactor barrels in the petrochemical industry, crankshafts and rudder rods in the shipbuilding industry, various large shafts and pressure cylinders in the heavy machinery manufacturing industry, gun barrels in the defense industry, large bearing rings, gear blanks, modules and other basic parts. Therefore, the production progress of large heavy forgings is of great significance to the development of the national economy, its scientific and technological level, production capacity and economic and technical indicators often become an important symbol to measure the level of industrial development of a country.

The main characteristics of the production of large heavy forgings are.

(1) strict quality requirements: As most of the large heavy forgings are key parts in the machine, special working conditions, complex force situation, requiring its quality to be reliable and excellent performance to ensure safe operation. With the development of industrial machinery to high performance, high parameters, large-scale direction, the technical conditions of forgings and quality level requirements are increasingly high. However, the current improvement in the quality of raw material metallurgy, optimization and control of forging and heat treatment processes, and progress in quality analysis and inspection technology are not yet compatible with it. Therefore, how to improve the quality of large forgings has become the main contradiction in the production of large heavy forgings.

(2) complex process: the production process of large forgings including smelting, ingot casting, heating, forging, rough machining and heat treatment. There are many work sequences, long cycles, strong continuity, collective labor and complex production technology.

(3) High production costs: large forgings consume large amounts of raw materials, energy, labor and tools, have long production cycles, occupy large equipment, and have high production costs. Therefore, it is of great technical and economic significance to improve material utilization, reduce consumption and scrap rate.