Forged steel ball having surface of martensite and inner core of soft bainite for grinding mill

Abstract

The invention refers to a forged steel ball applied to a ball grinder or a grinding mill, mixed by the following components (weight rat): C:0.57%-0.67%,Mn:0.70-1.00%,Si:0.17-0.37%,Cr:less than 0.25%,S:less than 0.035%,P:less than 0.035%,impurities:0.96-0.98%, and a residual amount of Fe. The steel ball is heated at a temperature of 1100-1200 DEG C to perform hot free forging process until the temperature is lowered to 870 DEG C; the steel ball performs isothermal heat treatment at the temperature of 25-35 DEG C; the steel ball at a temperature of 780+ / -10 DEG C is dipped in a cooling water at a temperature of 35+ / -5 DEG C; and the steel ball performs natural cooling process at normal temperatures to form a steel ball composed of a martensitic structure under hardness HRC62, and a martensitic structure with inner core of soft bainite greater than HRC40.

Description

technical field [0001] The invention relates to a forged steel ball, which is used in a ball mill for grinding raw materials or a tube mill for grinding ore in the cement production process. More specifically, the hardness values ​​of the central part and the surface layer of the 90mm forged steel ball are respectively Rockwell (Rockwell) Above HRC40, below HRC62. Background technique [0002] Generally, forged steel balls are used as grinder parts for grinding raw materials in cement plants or mining industries, and their main components are high-carbon steels of KS classification S45C series (wt% C: 0.42-0.48%, Si: 0.15-0.35% , Mn: 0.53-0.90% P: 0.03% or less, S: 0.035% or less Ni: 0.06%-0.20), the manufacturing method is to carry out the hot forging process first, and then go through simple heat treatment. However, the forged steel balls obtained by the above method are as follows: Figure 1a or Figure 1b As shown, the surface layer is martensitic structure, while the ...

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Problems solved by technology

[0007] The present invention is made to solve the problem that the surface hardness of a 90mm forged steel ball cannot exceed HRC56 in the technology of forging S45C material steel balls. Its purpose is to provide a forged steel ball that can reduce the content of chrome from the original 17% is reduced to less than 0.25%, which makes it more environmentally friendly than high-chromium alloy casting balls; maintains the advantages of traditional S45C material forged steel balls that will not break during thermal changes; at the same time, it also has better durability than high-chromium alloy casting balls Abrasive

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