SU905298A1 - Method for thermoplastic strengthening of parts - Google Patents

Description

The invention relates to methods for thermoplastic treatment of carbonaceous and alloyed steels and can be used hl hardening of various parts. There is a known method for increasing the strength of aapay by surface ordering with heating by high-frequency currents in combination with surface plastic ceforming II. The disadvantage of the method is that with such a hardening, the strength of the metal tensor increases, but its plasticity decreases. There is also known a method of thermocyclic treatment of carbon steels, according to which the production of multiple (4-6 times) rapid heating temperatures is 40-6СРс above the Ас line., I.e., about 76 ° 78СЯС, at a speed of 50-150 С per minute, then cooled in air at a rate of 1O per minute to temperatures 40-60 ° C below the line Ar, i.e. 590-6, and further cooling of the proi: t byutro (in voie or oil). To relieve internal stresses after thermal cycling, low tempering is performed at 150-200 ° C, followed by air cooling. The known method of heat treatment increases the ductility of the metal 23. However, the strength properties of the metal are reduced. In order to ensure the reliability of the rod of a parseozero hammer operating in the form of shock stress, the material of the rod must simultaneously possess high strength and plastic properties. The purpose of the invention is to increase the fatigue strength of the rod. The goal is achieved by the fact that according to the method of thermal processing, which includes multiple heating and cooling, quenching and tempering, the surface layer of the rod is heated to a temperature of 6 ° –8 ° C above the TsSO line at a rate of 45–55 degrees / second and cooled to a temperature of 5 ° –7 ° C below the LIH390 LI Ar, during the post-heating cycle, the rod is surfaced after surface plastic deformation in the intercritical gemperctal interval at a degree, aeformation of 30-50%, and after quenching, high tempering at 52 ° –56 ° C with subsequent cooling e. The drawing shows the installation diagram of al thermoplastic hardening rod. The rod I is installed in the lathe between the chuck 2 and the center 3. On the caliper there is an inductor 4 al heating the surface of the rod. A rolling device 5 al surface plastic deformation is fixed in the tool holder. The stem surface is 5–7 mm deep and, equal to the length of inductor 1a, is heated to a temperature of 60–80 ° C above the Ac / 1 line at a rate of 50 ° C in s. Moving the caliper together with the inductor along the axis of the rod, heat the desired section of the rod at the specified temperature. At the same time, the previously heated section of the rod is cooled to a temperature of 5 ° –7 ° C from the bottom line Ag. By reciprocating the support together with the inductor along the desired portion of the stem, the required number of heating and cooling cycles is obtained. After heating the surface of the rod during the last cycle to a temperature of 60-80 ° C above the AC / line. (Using a rolling device, surface plastic deformation is performed in the intercritical temperature range at a degree of deformation of 30-50%. After quenching the rod, high tempering is performed at 52 ° C. 560 C with subsequent cooling in air. Heating modes and deformation modes for steels are given in Tables 1 and 2. The proposed method of thermoplastic rod strengthening reduces the elastic modulus of the surface layer and leads to that the compressive stress of the surface layer is reduced compared with the core voltage, therefore, the rod is able to withstand a greater number of loading cycle, since the center of the nucleation of the fatigue crack moves into the depth of the body of the sttsysa, where the nucleation and the rate of propagation of the crack are slower. The hardening by sevenfold cyclic heating and deformation are heating rates of 45-55 ° C / s, degree and deformation of 30% -50% at HarpeBat ,,, and 750 ° СЛуу 61О ° С for steel 45 and i d 85O ° CL.60O ° C for 18HNVA styles. When using these modes of hardening, the fatigue strength of steel 45 and 18ХНВА increases 1.6 times and 1.3 times, respectively, compared to the known method of hardening. Table 1b

five

18.5

15 19

16.4 2O

18 22

20 25

22.5

13

8.2

42.4

2POOO 49.8

203OO 5 2, 6

2010O 44.7

20300 39.0

2О4ОО

110

33.0

20400 With the way

40 45

five

0.3 0.23 50 0.2 0.18

55

40 45

0.16 0.15

50 55 0.12 0.1 Note. Constant parameters number of heating cycles 7.

Claims (2)

Invention Formula The method of thermoplastic hardening of cetals. Preferably, a steam locomotive stem, which includes multiple heating above the Ai cooling below Ar. cooling and tempering, characterized in that. that, in order to increase fatigue strength, the surface surface of the component is heated to a temperature of 60–8 ° C with a higher rate of 4555 degrees / s and cooled to a temperature of 50–7 ° C. one Table 2 17 22 39.7 2030О 52.7 20100 25 2О2ОО 45.3 28 41.8 2ОООО 2О4ОО 63.6 203OO 64.5 77.8 195OO 41 74.2 2O1OO 5O The heat component is subjected to plastic deformation in the intercritical temperature range with a degree of deformation of 3050%, after which the depositing and high tempering are carried out. Sources of information taken into account in the examination 1. M. Balter. Hardening machine parts. M., mechanical engineering, 1978. with. 145-147. 2. Authfskoy certificate of the USSR 459518. cl. C 21D 1/00, 1975. Tagging, ri testing of samples treated with known (deformation degree 40%, heating cycle number 7). processing: heating rate 5 ° C / s;