SU1733495A1 - Steel - Google Patents

Abstract

The invention relates to metallurgy, in particular to steel for the production of grinding rolled grinding balls which are thermally hardened from rolling heating. The aim of the invention is to increase the impact strength, wear resistance, reduce the splitting of the grinding bodies. This is achieved by additional doping with one element from the group containing niobium and cerium, with the following ratio of components, wt.%: Carbon 0.5-0.85; manganese 0.7-1.5; silicon 0.8-1.5; aluminum 0.002-0.06, said element 0.0002-0.05; iron else.

Description

The invention relates to ferrous metallurgy, in particular to steelmaking, and can be used to produce grinding bodies.

For the manufacture of grinding media, for example rolled balls, carbon steel with up to 0.6% carbon and up to 0.4% silicon doped with 0.4-2.0% manganese or steel P-65 containing,%, is used: carbon 0.7-0.82; manganese 0.7-1.06; silicon 0,26-0,40.

The disadvantages of balls made from these steels are low impact strength and wear resistance, as well as increased hotness of the balls, which increases their production and leads to a significant consumption of grinding balls during their operation.

Closest to the proposed steel, used in the manufacture of grinding bodies, composition,%: carbon 0.52-0.75; silicon

0.85-1.2; manganese 0.8-1.7; aluminum 0.06-0.05; titanium 0.01-0.06; iron else.

The disadvantages of the well-known steel are low impact strength and wear resistance, increased splitting, which reduces the profitability of production and increases the cost of producing balls.

The purpose of the invention is to increase the impact strength and wear resistance, reducing the splitting of grinding balls while reducing their production.

The goal is achieved by the fact that one element from the group containing niobium and cerium is additionally introduced into the steel, with the following ratio of components, wt.%:

yo

00

with

four

about ate

Carbon Manganese Silicon Aluminum

0.50-0.85 0.7-1.5 0.8-1.5 0.002-0.06

One element from the group containing niobium, cerium 0.0002-0.05 IronEstal

The steel contains impurity elements: nickel, chromium and copper (not more than 0.3% of each), which are not controlled, as well as sulfur and phosphorus in the amount of up to 0.05% of each.

The essence of the invention is that the introduction of one element from the group containing niobium and cerium into the steel in the specified amounts for a given content of carbon, manganese, silicon and aluminum provides an increase in impact strength and wear resistance, reduces splitting and specific consumption of balls during operation. due to the intensive formation of complex-alloyed carbides, grinding the grain, cleaning the boundaries of the austenitic grains from harmful impurities, increasing the length of the martensitic and semi-martensitic zones, as well as in the result of the formation of a multilayer microstructure with optimal properties over the cross section.

The lower limit of the carbon content (0.5%) is assumed on the basis of the need to ensure the specified minimum calcination and hardness during heat treatment of the balls, and the upper (0.85%) is determined by the technological ductility during their rolling, which decreases to dangerous limits. with an increase in the carbon content above the specified norm, as well as optimization of the cleaved ™ in the operation of balls.

The limitations on the silicon content are due to its effect on the hardenability and the segregation heterogeneity: when the content is less than 0.8%, silicon has practically no effect on the hardenability, and if the content is more than 1.5%, its negative effect appears. on segregation heterogeneity.

The limits of the manganese content are determined based on its effect on the hardenability and size of the austenitic grain: with a content of less than 0.7%, manganese does not affect the utilization, and with a content of more than 1.5%, it increases the tendency of the steel to grow austenitic grain.

The lower limit of the aluminum content (0.002%) is due to obtaining the necessary deoxidation and the beginning of the positive effect of aluminum on the grinding of steel grains, and at a value of 0.06%, the negative effect of aluminum on the surface quality of the ingots begins to appear

due to the reduced fluidity of steel.

When the content of niobium and cerium in the amount of 0.0002%, they contribute to the formation of complexly doped carbides, which have a positive effect on the grinding of austenitic grain and clearing their boundaries from harmful impurities (phosphorus, sulfur, etc.), as well as increasing the impact strength and size of the increased hardness Increasing the content of these elements in excess of 0.05% is economically unjustified and impractical because of their negative effect on the fluidity of steel and on the surface quality of the balls, as well as their splitting.

Five heats of the proposed steel and two well-known were melted, which were rolled on balls with a diameter of 120 mm, and then from a rolling end temperature of 930–960 ° C were subjected to strengthening treatment in a chamber device and in a quenching tank according to a well-known scheme.

The hardness, size of the semi-martensitic zone, wear by weight loss under abrasive wear, splitting, assessed by the number of balls cracked after the mill’s operation for 1 month of the total number of balls loaded, and impact strength determined by the values of the fracture work obtained during impact stretching of cylindrical specimens on an MK-30 manic ram.

The chemical composition of the experimental heats and the results of the comparative tests are shown in the table.

Analysis of the data in the table shows that the steel of the proposed composition possesses, compared to the known steel, increased by 100-200 HB hardness, higher wear resistance and impact strength, reduced splitting, as well as a much larger semi-martensitic zone, which reduces the specific consumption of the balls during grinding. Verdekh ore materials.

In this case, due to a decrease in the callability of the balls, both during heat treatment and during operation, the production of grinding balls becomes cheaper.

The steel of the proposed composition can be melted in open-hearth furnaces and in converters. Doping is carried out by introducing silico-manganese and ferrosilicon into the melting unit and aluminum and rare-earth metals in the ladle.

Claims (1)

Claim Steel mainly for grinding rolled balls containing carbon, manganese, silicon, aluminum and iron, characterized in that, in order to increase impact strength, wear resistance, reduce splitting ™ grinding media, it additionally contains one element from the group comprising niobium and cerium, at Steel The content of elements,% Si Al Kb the following ratio of components wt.%: Carbon Manganese Silicon Aluminum One element from the group containing niobium and cerium. Iron Xie Wear g Impact strength, kgm 0.50-0.85 0.7-1.5 0.8-1.5 0.002-0.06 0.0002-0.05, the rest Cracking The size of the semi-martensitic zone, mm 0.50 0.70 0.80 0.002 0.023 0.027 0,0002 436 0.41 11.6 2,4 21 0,025 - 437 0.35 12,2 . 2.2 19 0.05 - 504 0.37 13.1 2,3 23 ' 0,0002 43 ’ oh zg 12.3 2.2 19 0,0251 502 0.40 14.1 2.6 18 0.05 506 0.36 12.7 2.9 24 Pre- 0.67 eleven 1.15 0,031 0.026 0.022 0,0002 - 457 0.32 12.7 3,7 26 lag 0,0251 - 503 0.29 13.3 3.2 25 eatable 0.05 - 503 0.30 13.9 3.6 22 0,0002 500 0.27 12.6 3,1 23 0,025 437 0.31 13.1 2.9 21 0.05 512 0.29 12.9 3.2 24 0.65 1,5 1,5 S 06 0.015 0.032 C, 0 O 0 L - 517 0.22 16.1 17.0 3.6 26 0,0249 - 520 0.19 3,1 28 0.05 - 524 l 24 15.9 3.0 27 0,0002 503 0.30 16,4 2.9 27 0,0251 506 0.23 15.7 3,5 25 0.5 512 0.26 17,2 3.2 26 Of- 0.52 1.70 0.8? 0.09 0.025 0.027 - - 420 0.97 10,2 4.7 9 West 0.75 ’, 32 1,2 0.2 0.019 0.029 - - 436 0.73 8.7 5.3 12 may Editor A. Ogar Compiled by L. Pozdnyakov Tehred M. Morgenthal Corrector E. Lonchakova Order 1641 Circulation Subscription VNIIIPI of the State Committee for Inventions and Discoveries under the State Committee for Science and Technology of the USSR 113035, Moscow, Zh-35, Raushskaya nab., 4/5 Production and Publishing Plant Patent, Uzhhorod, 101 Gagarin St.