SU1353832A1 - Method of surface strengthening of steel components - Google Patents

Abstract

The invention relates to methods for surface hardening of steel parts under induction heating and can be used to process parts operating under wear conditions under high dynamic loads. The purpose of the invention is to improve the quality of the surface and increase the productivity of the process. The method involves heating parts in kerosene up to 1100-1145 ° C at a speed of 50-250 ° C / s without isothermal exposure, while between the heating rate Vj, the heating temperature TC and the temperature of the eutectic reaction TA they maintain the HTTL + ratio (1 .... 3) V. The application of the method makes it possible to obtain on the surface of products the ledeburit layer with the required depth and surface cleanliness, which makes it possible to eliminate subsequent mechanical processing. 1 hp f-ly, 1 tab. from 9 cl CA: ate from 00 so

Description

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The invention relates to metallurgy, in particular, to methods of induction heat treatment of steels, and can be used for surface hardening of products operating under conditions of intense wear. The purpose of the invention is to improve the quality of the surface of the parts and increase the productivity of the consolidation process.

It was established experimentally that when processing parts according to the proposed method, the amount of carbon in the surface layer increases to 2-3.5%. In this case, a eutectic reaction occurs with partial formation of a liquid phase. The ratio of the main heating parameters (velocity and temperature) makes it possible to fix the optimum combination of the liquid and solid phases in the structure of the surface layer up to 90 microns thick at the saturation temperature. At the same time, the solid phase significantly reduces the fluid-rich layer, which is important for maintaining the surface shape. Heating in kerosene provides a thin and dense layer on the surface.

soot - coke crust thickness of about 30 with the known proposed method allowed 0.02 mm. Lastly, the further penetration of atomic carbon to the surface of the product is difficult, and thus prevents it from transfusing and increasing the amount of the liquid phase, prevents the spreading of already formed portions of the liquid and the formation of droplets and leaks on the surface.

Example. Heating of ball pins made of steel 40 XH is conducted in kerosene from a lamp generator with a frequency of 66,000 Hz. Temperature control is carried out using an electronic potentiometer, as well as by adjusting the time and electrical par- meters of the heating mode.

When the heating temperature is lower and the heating rate of the less ledeburit zone is absent, when the temperature and heating rate of the upper limits of the proposed interval are exceeded, an insulating crust breaks out and the surface quality deteriorates markedly, which leads to an increase in the total duration of the hardening process.

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It eliminates post-machining operations.

Ula Invention Form

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Claims (2)

1. The method of surface hardening of steel parts, including induction heating in kerosene and melting of the surface zone, is so that, in order to improve the quality of the surface of the parts and increase the productivity of the process, heating is carried out to teMnepaTyry 1100-1145 ° C at a speed of 50 to 250 ° C / s. , 2. The method according to claim 1, of tl and h and y - yi and s. the fact that the heating temperature T n is determined from the ratio TH T + (1 ... 3) Wn, where TC is the heating temperature, C; Tl - eutectic temperature reactions, C; V, j - heating rate, ° С / s. When the ratio between temperature and heating rate is upset (Vv), the amount of liquid phase due to temperature rise, increase in heating time and surface oversaturation with carbon increases so that the protective coke crust cracks, intense atomic carbon flow to the saturable surface disappears, disappears the solid component in the surface layer and the liquid phase instantly forms droplets and drips on the surface of the product. Surface quality decreases dramatically. If this ratio is violated in the direction of decreasing temperature (), it is not possible to exceed the eutectic temperature for structural engineering steels and, after cooling, the ledeburite component is absent in the alloy structure, causing an increase in durability. The results are shown in the table. Comparison of data given in table shows that by comparison with the famous proposed method It eliminates post-machining operations. Ula Invention Form 1. The method of surface hardening of steel parts, including induction heating in kerosene and melting of the surface zone, is so that, in order to improve the quality of the surface of the parts and increase the productivity of the process, heating is carried out to teMnepaTyry 1100-1145 ° C at a speed of 50 to 250 ° C / s. , 2. The method according to claim 1, about tl and h and y -. u and u with. the fact that the heating temperature T n is determined from the ratio TH T + (1 ... 3) Wn, where TC is the heating temperature, C; Tl - eutectic temperature reactions, C; V, j - heating rate, ° С / s.