SU1046339A1 - Method for boronizing steel products by electrolysis - Google Patents

Abstract

A METHOD OF ELECTROLYSIS VERIATION OF STEEL DETAILS, including boronation in an electrolyte with a cathode current density of 0.5–0.7 A / cm2 for 15–30 min, subsequent shutdown of current and exposure for 30–120 min, characterized in that increasing the efficiency of the process, boronization in the electrolyte is carried out at 740-760 ° C, and holding the electrolyte in the electrolyte when the current is turned off is at 850-900 ° C, while the parts being processed are heated and the temperature is 30-50 ° C; With ibxue electrolyte temperature.

Description

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The invention relates to metallurgy, in particular to diffusion methods for treating the surface of metal products, and can be used for boring cold and hot stamping dies and injection molds.

A known method of electrolytic boronation of steels in a molten drill, consisting in preliminary electrolysis boronation at 1223.K (950 ° C) for 3 hours at a current density of 0.2 and subsequent liquid boronization at 1253-1323K (980-1050c) ClJ.

However, according to this method, it takes a long time to obtain boron layers with a depth of 0.6 mm and a hardness of H 16000 MPa, as a result of which the crucible and graphite anodes are often destroyed due to the high temperature and oxygen of the atmosphere. is graphite.

The closest to the technical essence and the achieved effect to the proposed is a method of electrolysis boring of steel parts, in which electrolysis boriding is carried out at .1053-1093 K (780-820s) with a cathodic current density of 0.5-0.7 A / cm 2 within 3012–0 min, depending on the depth of the boronized 2J layer,

However, electrolysis boronation at 10S3-1093K (780-820 ° C) with a cathodic current density of 0-0-0-A / cm for 15-30 minutes occurs under conditions when the temperature of the part to be borne is equal to that of electrolyte when boring alloyed steels of the type 5ХНМ, 4Х5МФС and others, it does not always guarantee the formation of a layer of a given depth. Exposure at a high temperature of 1173-1273 K for 30-120 minutes causes significant overheating and oxidation of the crucibles (900-1000 ° C).

The aim of the invention is to increase the efficiency of the process.

This goal is achieved by the fact that according to the method of electrolysis boring of steel parts, including boronation in an electrolyte with a cathodic current density of 0.5-0.7 A / cm 2 for 15-30 minutes, subsequent shutdown of current and exposure for 30-120 minutes , boronization in the electrolyte is carried out at 740-7bO ° C, and holding at 850-900 ° C, while the parts being processed are heated and their temperature is maintained at 305 ° C above the electrolyte temperature.

At the first stage, the required amount of boron on the part to be borated is extracted with a high speed under the action of an electric current; in the second stage, it is diffused into the part with the current turned off. High density. The current provides a high rate of boron release on the parts, and, consequently, a small residence time of the anodine in the bath; lower electrolyte temperature (30–50 degrees below the part temperature) reduces the harmful effects of atmospheric oxygen on the crucible material and material

0 anode.

Example 1. Hot stamping is subjected to boring. The dimensions of the liner 0 100x20 mm. Material steel 5HNM. The enclosed enclosure with a heater is installed in a crucible with electrolyte melted in an electric furnace (85% borax and 15% of powdered salt) at 1023 K (750 ° C). At the same time, immersed in the electrolyte and graphite anodes. The heat power of the heater is regulated in the range from 3 to 5 kW, while maintaining the temperature of the liner 30 degrees above the electrolyte temperature, i.e. 1053 .K ().

They turn on the direct current, set the current density to 0.5-0.7 A / cm and conduct electrolysis for 15 minutes.

After that, the current is turned off, the anodes are removed from the bath, and the temperature

0 liner support for 30 degrees--. The temperature of the bath is higher during heating and during the subsequent aging for 30 min at 1123 K (& 5 () ° C). After aging the stamp is subjected to

5 hardening, salt washing and tempering. PRI mme R 2. Boring is subjected to liners molds cast under pressure. The dimensions of the liner 300x250x70 mm. Material steel

n 4H5MFS. A bored liner with a heater is installed in a crucible with electrolyte melted in an electric furnace (85% borax and 15% sodium chloride) at 1033 K (7 ° C). At the same time, graphite anodes are immersed in the electrolyte. The heat power of the heater is controlled in the range of 5-10 kW, which maintains the temperature of the liner 50 degrees above the electrolyte temperature 1083 K

0 (810 ° C). They turn on the direct current, set the current density to 0.50, 7 A / cm and conduct electrolysis in a leak for 30 minutes. After that, the current is turned off, the anodes are removed from the bath, and

5 bath temperature is raised to

1173 K (900 ° C), maintaining the temperature of the liner 50 degrees above the temperature of the bath when heated and in the process of subsequent exposure to

0 for 120 minutes

After exposure, the deposits are subjected to quenching, salt washing and tempering. The table shows the comparative data from tests of the known and proposed methods.

4H5MFS

thirty

0.5

up to 147.3

0.25 16000

1073 (1200) (800) and 1273 (1000)

Improving the efficiency of the method is due to the reduction of energy consumption, increasing the resistance of the crucibles and anodes by increasing the working life of the electrolyte used. The increase in crucible resistance was estimated by comparing the average resistance of a batch of three experimental crucibles when the process was carried out in a known manner with the average resistance of three experimental crucibles, in which the boronization process was carried out according to the proposed method. It has been established that the average resistance of crucibles made of 1X18H10TL steel by a known method is 600-800 hours of continuous work according to the proposed method, the duration of continuous operation of the same crucibles increases to 9001200 hours. Similarly, the resistance of electrodes and electrolyte was evaluated. The duration of continuous operation of graphite electrodes according to a known method was on average 20.0 hours. 1 The temperature reduction of the proposed method allowed the electrodes to last up to 240 hours. A decrease in the working temperature of the electrolyte by 30-60 degrees significantly slows down the development of oxidation and dissolution processes, as a result What the electrolyte does not fill The gases from the atmosphere, iron and other elements of the crucibles. The strength of electrulite increases from 400 to 480. 500 h. Using the proposed method of electrolysis boronation as compared with the known method allows reducing the temperature of the electrolysis bath by 30-50 degrees, reducing the temperature on the outer surface of the crucible by 250 degrees and thereby increasing the resistance of the crucible by 30-50%, and the stability of the anodes and electrolyte raise by 20-30% at. preserving the strength properties of machined parts.

Claims (1)

(57) METHOD FOR ELECTROLYZING BORING OF STEEL PARTS, including boronation in an electrolyte with a cathode current density of 0.5 0.7 A / cm ² for 15-30 minutes, subsequent shutdown of the current and holding for 30-120 minutes, characterized in that, in order to increase the efficiency of the process, boroning in the electrolyte is carried out at 740-760 ° C, and holding in the electrolyte when the current is cut off is carried out ^ at 850-900 ° C, while the workpieces are heated and their temperature is maintained at 30-50 ° With electrolyte temperature.