SU1234440A1 - Method of heat treatment of high-carbon alloyed steels - Google Patents

Description

And the fusion process relates to heat treatment and can be used but in the heat treatment of rolled or finished products from high carbon alloyed steels to obtain the structure of granular perlite in them.

The purpose of the invention is to reduce the processing time,

The invention is illustrated by the following example.

The proposed method of heat treatment was tested on samples of the melted smelting of ShKh15 steel with a diameter of 4 mm and a length of 1000 mm with the initial structures of lamellar perlite and bainite. The initial hardness of lamellar perlite is 325 HB, bainite 359 HB. For heat treatments, a tubular furnace is used, the thermal mode in which is regulated by changing the current strength. The application of bending ultrasonic vibrations with a frequency of 9.5 kHz is carried out using direct acoustic contact of the oscillatory system with the lateral surface of the sample with the amplitude of the shift

govy strain.

The proposed heat treatment method is carried out as follows: I I

High carbon alloyed steel, predominantly bearing steel with the initial structure of bainite, is heated at a rate of 150 ° C / min to a temperature of 770-790 ° C. The choice of this temperature range is due to the fact that at a temperature below 770 C, diffusion of carbon and alloying elements, causing the nucleation of centers, to slow down granular perlite and its growth. When the steel is heated in accordance with the state diagram, the carbide phase dissolves and the nucleation of granular pearlite is eliminated. With an initial bainitic structure, a latch of at least 5 minutes provides the necessary hardness (186-190 HB) and structure (1 point). Reducing the delay time of less than 5 minutes leads to the formation of a finely dispersed pearlite structure and increased hardness. In the case of the initial structure of lamellar pearlite, the lid within 5 minutes is insufficient, which is confirmed by the presence of a heterogeneous structure of granular perlite, areas

ten

5 23Д4ДО2

gshastinchatog psrlith-h and a uniform hardness. After aging, the steel is cooled for 15-32 minutes to the following:

thirty

40

min cooling

BOO-BZO with the simultaneous suppression of bending ultrasonic coils in the range of shear strain amplitudes 3, -3.6x10. When the temperature reaches 600-650 ° C, the rate of further cooling is not regulated.

Excitation of flexural ultrasonic vibrations, having shear deformation components, leads to an additional increase in the defect density of the crystal structure and a qualitative transformation of the dislocation structure of the metal as compared with the effect of longitudinal vibrations, which cause deformations of compression and stretching. At an accelerated density, spheroidization of cementite is observed. Choice as

 The structure of bainite is caused by the fact that this type of structure is formed as a result of shear diffusion-free phase transformation and leads to an accumulation of the apparent density of crystal structure defects inherited by the post-phase phase OS - as a result of austenite of the dislocation structure formed during shear diffusionless phase transformation is observed, as was established Experimentally, a new qualitative effect, manifested in the acceleration of the formation of germs of granular perlite, in an increase in the rate of their growth and reduction in the time of thermal treatment as compared with the known method, in which plate pearlite was chosen as the initial structure, and Pro: longitudinal fluctuations

The table shows the modes of heat treatment of high carbon EXPERT alloy steel 11X15 known50

ny and ki.

The proposed methods of processing. From the table it follows that the use of ultrasonic bending vibrations with shear components

deformation during heat treatment of steel with the initial bainitic structure allows to reduce the annealing time by 2.5 times and at the same time get

Heating to minimum optimum temperature

Total min

o Heating rate, C

minimal

maximum

optimal Time of holding, min

minimal

maximum

optimum cooling to tempera

minimal

maximum

optimal creep time, min

minimal

maximum optimal

Longitudinal amplitude is minimal

perlite hardness and structure in accordance with the requirements of the standard (according to GOST 801-78 hardness 179-207 HB; structure up to 4 points).

3.6 X 10

3.6 X 10

3.6 X 10

-four

maximum

optimal

 1 Time for min

""

four("

The method using longitudinal ultrasonic vibrations, the original structure is perlite,

The method of using bending ultrasonic vibrations, the original structure is perlite,

The original structure is bainite,

Editor And Slobodko Nick

Compiled In, Chinese

Tehred V. Kadar Proofreader I. Muska

Order 2955/31 Circulation 552Subscription

VNIIPI USSR State Committee

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

Production and printing company, Uzhgorod, st. Project, 4

Table continuation

3.6 X to 2 X .10

c1

3.6 X 10

2 X 10

.-e

Claims (1)

METHOD FOR THERMAL TREATMENT OF HIGH-CARBON ALLOYED STEELS mainly with the initial bainite structure, including heating to a temperature in the range And _{with <} -A _St , holding, cooling to a temperature of 20-30 ^d C below A _{g <} with simultaneous ultrasonic action and final cooling, characterized in that, in order to reduce the processing time, the ultrasonic effect is carried out by bending vibrations with a deformation amplitude exceeding the threshold amplitude of shear deformations in the metal. SU „„ 1234440 12344 ^ 0