A Control Method for Hot Rolling Crack Expansion of 42crmo Steel Centrifugal Cast Billet Ring

Abstract

The invention discloses a heat-rolling and expanding crack control method for a 42CrMo steel centrifugal casting blank ring piece, and belongs to the technical field of ring piece forming, and is characterized by comprising the following technological steps: 1) electromagnetic centrifugal casting the 42CrMo steel ring piece blank, adding a steady magnetic field around the outside of the non-magnetic cast iron mould with the magnetic field intensity at 0.1- 0.5 T, the rotating speed of the casting mould at 320-360r / min, the casting temperature of the metal liquid at 1,520-1,540 DEG C, and the casting speed at 23.7-26.4 kg / s; 2) performing two-stage homogenization treatment on the centrifugal casting ring piece blank; 3) hot-rolling and expanding the centrifugal casting ring piece blank: thefeeding speed is determined by the thickness reduction amount and the height reduction amount of the wall thickness in different stages, a gradually increasing cooling water spraying flow rate is adopted from a surface layer to a middle layer, and a layered cooling water spraying flow rate is 30-35 m3 / h; 4) carrying out multi-stage cooling treatment on the ring piece after rolling and expanding.The heat-rolling and expanding crack control method for the 42CrMo steel centrifugal casting blank ring piece has the advantages that the segregation of the alloy elements can be reduced, the crack defects can be eliminated, and the uniformity and the mechanical property of the tissues are improved.

Description

technical field [0001] The invention belongs to the technical field of ring forming, and in particular relates to a method for controlling hot rolling cracks of a 42CrMo steel centrifugal cast slab ring. Background technique [0002] Ring parts such as bearing rings and flanges are widely used as key connection, support and transmission components in major high-end technical fields such as aerospace, wind power, ships and automobiles. China Invention Patent Application No.: 201010132486.6, titled "A method for short-process casting-rolling composite forming of metal rings", the ring blanks produced by molten steel refining and centrifugal casting are directly hot-rolled and expanded, compared with the traditional ring production process , the process flow is alloy smelting-casting ingot-heating-billet opening-cutting-heating-upsetting-punching-heating-rolling, which has the outstanding advantages of saving energy, saving equipment investment, high material utilization rate a...

AI Technical Summary

Problems solved by technology

However, when the casting-rolling compound forming process is used to produce rings, the macroscopic shape of the centrifugal billet and the modification of the internal microstructure are concentrated in the process of hot rolling and expansion. Improper setting will lead to defects such as cracks inside the finished ring

[0003] There are three reasons for the cracks of 42CrMo steel hot rolling forming rings: one is that the alloy elements segregate to the outer layer of the ring blank under the action of centrifugal force during the centrifugal casting process, resulting in the middle layer of the ring blank being the junction of heavy metal alloy elements and light metal elements , Fusion area, there are often defects such as stress concentration, porosity, voids, and macro-segregation; second, the unreasonable radial and axial feed speed and feed amount distribution during the hot rolling process, resulting in repeated compressive stress of the ring blank. Crack defects appear under the action of tensile stress; the third is that the cooling method of the ring after hot rolling is wrong. When the wall thickness of the ring is large, the inner and outer layers are not cooled uniformly, which will also lead to cracks

However, the existing technology does not provide an effective method for controlling and eliminating cracks in ring casting-rolling composite forming

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