Method for Eliminating Metallurgical Defects of Large Rings Formed by Cast-Rolling Composite

Abstract

The invention discloses a method for eliminating metallurgical defects of large annular parts in casting-rolling composite forming, and belongs to the technical field of production for large annular parts. The method is characterized by comprising the following process steps: step 1, directly heating hot annular blanks discharged from a mould for centrifugal casting; step 2, rolling the hot annular blanks by virtue of an unconventional technology, specifically, (1) radially rolling, (2) carrying out unconventional diameter-axial multi-cycle differential-temperature rolling, (3) forming, and (4) rounding. According to the invention, the purpose of eliminating the metallurgical defects of large annular parts in casting-rolling composite forming is achieved through improving a heating manner for the annular blanks, and improving a stress state of rolling for the annular blanks, thus the problems of surface cracks, substandard mechanical properties of partial areas, and high rejection rate, existing in application of a casting-forging integrated process for producing large annular parts, are effectively solved. The cost of the large annular parts produced by the method disclosed by the invention is reduced by 10% compared with the original cost, and the product percent of pass is increased by more than 90%; and the method has the advantage of realizing low-cost, high-performance and high-effect production.

Description

technical field [0001] The invention belongs to the technical field of production of large rings, and in particular relates to a method for eliminating metallurgical defects of large rings formed by casting and rolling. Background technique [0002] Ring parts are basic parts of industry, which are widely used in electric power, metallurgy, petrochemical, shipbuilding, railway, mining, aerospace, national defense and so on. In recent years, with the continuous development of integrated casting and forging technology, the method of directly processing the cast billet into parts by composite forging technology has become a research hotspot. At present, the newly developed large-scale ring casting and forging integrated production process is: centrifugal casting ring billet→cold billet heating→conventional rolling (Patent No. ZL201010132491.7 "A method for forming large ring parts by casting billet rolling") . Compared with the traditional single processing technology (smelti...

AI Technical Summary

Problems solved by technology

First of all, due to the large temperature difference between the inner and outer layers of the ring billet after centrifugal casting, it is easy to produce longitudinal cracks on the surface during the cooling process. In addition, the metallurgical quality and solidification characteristics of steel will inevitably have original defects such as inclusions, looseness, segregation, and cracks inside the ring blank. When using conventional technology for ring rolling, It is difficult for most of the rolling force to fully penetrate into the core of the cast ring billet, so that the original defects in the core cannot be fully eliminated, and thus inherited in the ring tissue

Therefore, the large-scale casting and rolling rings produced by cold billet heating + conventional rolling have serious problems such as surface cracks, substandard mechanical properties in some areas, and high scrap rate.

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