Cold charging production process of high-compactness and high-purity fine-grain grinding ball steel

Abstract

The invention discloses a cold charging production process of high-compactness and high-purity fine-grain grinding ball steel. The cold charging production process comprises the following processes ofpre-desulfurizing molten iron, smelting in a converter, refining in an LF furnace, carrying out RH vacuum treatment, continuously casting, slowly cooling a large round billet casting blank, heating,rolling, cooling, high-temperature pit entering slow cooling, pit exiting finishing, packaging and warehousing. According to the production process, a grinding ball steel round billet cold charging temperature control system is adopted for heating, and a mode of combining differential temperature rolling and single-pass high-pressure rolling is adopted, so that the deformation of the center of thebillet is increased, and the internal compactness and the grain size of the steel are improved. The grinding ball steel produced by the production process has the advantages of excellent macrostructure (central porosity is less than or equal to 1.0 grade and general porosity is less than or equal to 0.5 grade), high purity (A-type inclusions are less than or equal to 1.0 grade, B-type inclusionsare less than or equal to 0.5 grade, C-type inclusions are less than or equal to 0.5 grade and D-type inclusions are less than or equal to 1.0 grade) and fine austenite grains (austenite grain size isgreater than or equal to 6.5 grade). The grinding ball obtained by carrying out a conventional rolling process on the produced grinding ball steel is good in impact toughness and long in fatigue life.

Description

technical field [0001] The invention belongs to the technical field of steel manufacturing for wear-resistant balls, and in particular relates to a cold-packing production process of high-density, high-purity fine-grained steel for grinding balls. Background technique [0002] Although high carbon content can improve the wear resistance of steel balls, if such steel balls cannot be heated at high temperature for a long time to diffuse carbides at high temperature during rolling, massive carbides will be precipitated in the structure. Massive carbides will have a very adverse effect on the wear resistance and fatigue properties of steel balls. [0003] For the breaking of steel balls, it is mainly affected by two aspects. On the one hand, the broken balls produced by the steel balls during the manufacturing process; The cost of the ball. [0004] The control of broken balls in the steel ball production process mainly lies in the adjustment of the steel ball production plant...

AI Technical Summary

Problems solved by technology

[0005] Although the current hot charging or hot delivery process can reduce the production cost to a certain extent, because the steel billet has not undergone phase transformation and recrystallization process, the as-cast structure is coarse, which will be inherited to the subsequent rolling products. At the same time, in the hot charging Or in the hot delivery process, the hydrogen in the slab cannot diffuse in time, so that hydrogen exists in the rolled material. If the subsequent rolled material is not cooled properly, fatal defects "white spots" will appear inside the steel

Furthermore, the implementation of the hot charging or hot delivery process has high requirements for the connection between steelmaking and steel rolling processes. As long as one party fails or the matching is smooth, the other party will be forced to interrupt, which will result in hot blanks having to choose cold charging. craft

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