SU1217895A1 - Method of heat treatment of articles made of hypereutectoid steels - Google Patents

Description

The invention relates to the heat treatment of products made from eutectoid steels, and can be used in the manufacture of hot rolled pipes and bearing bearing steel.

The aim of the invention is to increase the productivity of the process and reduce the carbide mesh.

Heating below Ac - 40 ° C slows down the diffusional redistribution of carbon and does not eliminate the carbide net, at temperatures of heating Ac, the carbon goes into the austenite solution and upon subsequent cooling the carbide net is formed again. Subsequent regulated cooling at speeds of at least C / min to temperatures above Arg at 60-100 ° C is necessary to obtain a grain size in the final structure of granular pearlite in accordance with GOST 800-78.

Exposure when cooled below Ag, + + 60 ° C leads to the formation of granular perlite with a hardness of metal above 207 IV. Exposure during cooling above LR, + 100 ° C leads to the formation of coarse-grained perlite structure above the 4th point.

Example. A heat treatment of hot-rolled pipes of steel ShH-15 with a size of 155.5 X 18.9 mm was carried out in an amount of 25 pieces, concluding, and with heating up to 880 C,

Hardness HB

Carbide mesh

Granular Perlite Score

Compiled by L. Venderova. Editor T. Parfenova Tehred L. Mikesh. Proofreader A. Yaimokosov

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VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch P1Sh Patent, Uzhgorod, st. Project, 4

178952

1 h, cooled to 780 C at a rate of Yu C / min, aged at 780 ° C for 2 hours, cooled to 680 C at a speed

5 30 C / h, further cooled in air.

At the same time, heat treatment was carried out on 25 pipes according to the prototype method: heating to

0 hr 6 h, cooling in the oven to 680 ° С at a speed of 40 s / h, then in air.

The duration of heat treatment according to the proposed method is 7 hours, and according to the prototype method 10.5 hours.

The table shows the results of studies carried out on products processed according to the proposed and known methods, as well as the requirements imposed on metal and steel pipes ShH-15 according to GOST 800-78 and GOST-801-78.

As can be seen from a comparison of the data presented, the heat treatment of hot-rolled cast steel pipes ShH-15 using the proposed method ensures the obtaining of properties in metal of the pipe (hardness, elimination of carbide

nets, etc.), according to GOST 800-78 and GOST 801-78, with a simultaneous reduction in the duration of the process.

187-207 179-207

1 2 H 1, i, J

1,2,3

la, 2,3,1 1,2,3

Claims (4)

I. METHOD FOR THERMAL TREATMENT OF PRODUCTS FROM ZAEUTEKTOIDNOYE STEELS, mainly pipes from ball-bearing steels, including heating in a furnace to a temperature above Ac _f , holding at supercritical temperatures, cooling in the furnace to subcritical temperatures, and further. air cooling, characterized in that, in order to increase the productivity of the process and reduce the carbide network, heating is carried out to a temperature from Ac ^ -40 ° C to Ac _t , holding at this temperature and cooling to supercritical temperatures. 2. The method of pop. ^ characterized in that the shutter speed at a heating temperature is carried out for 10-60 minutes 3. The method of pop. ^ characterized in that the undercooking is carried out to a temperature of 60-100 ° C higher, than Ar ^ with a rate of at least 3 ° C / min. 4. The way popp. 1 and 3, characterized in that the temperature at a temperature of 60-100 ° C above Ar is carried out for 30-150 minutes. JV> 12) 7895 holding for 1 h, cooling to 780 ° C at a speed of 1 () ° C / min, holding at 780 ° C for 2 hours, cooling to 680 ° C at a speed 30 ° C / h, further cooled at