SU1148883A1 - Method of heat treatment of high-speed tools - Google Patents

Abstract

1. METHOD FOR THERMAL TREATMENT OF TOOL FROM QUICKLY CUTTING STEEL, which includes the first quenching from the temperature below adopted, the second standard quenching and tempering, characterized in that, in order to increase the wear resistance, the first quenching is carried out from 1100-1120 ° C with cooling air flow. 2. A method according to claim 1, characterized in that the holding at the first quenching is carried out for 3-5 minutes.

Description

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The invention relates to mechanical engineering, primarily to instrumental production, and can be used for thermal processing of products made of building steels.

The known method of heat treatment of high-speed steel, including double-hardening and tempering. In order to increase the wear resistance of the tool after heating for the second quenching, isothermal aging in a salt bath at 830-850 ° C for 5-20 minutes 1 is carried out.

However, the wear resistance of the tool is increased by only 20-40%.

The closest to the proposed technical essence and the achieved result is a method of heat treatment of high-speed steel, including double quenching and tempering with conducting the first quenching from a temperature of 20-35 ° C above Acé point. The method provides an increase in strength properties by obtaining a polygonal substructure 2.

However, the processing according to a known method does not fully provide the possibility of increasing the wear resistance.

The purpose of the invention is to increase the tool durability.

To achieve this goal, according to the method of heat treatment of high-speed steel tools, including the first quenching from the temperature below the adopted, the second standard quenching and tempering, the first quenching is carried out from 1100-120 ° C with cooling in an air stream.

In this case, the first quenching is carried out within 3-5 minutes.

Studies performed on the first quenching mode show that when quenching from 850-1000 ° C followed by various cooling modes, the cutting properties of the tool do not significantly improve. The solubility of alloying elements in austenite increases in direct dependence on temperature and duration of exposure. The fixation of the structure and substructure during primary quenching is practically preserved and does not relax, the microvoltages and the supersaturated solid solution do not have time to return to a stable state due to low exposure (3-5 minutes) before heating for the second quenching. Heating above 1150-1200 ° C leads to an increased tool curvature.

Example. Drills with a diameter of 21.25 mm are loaded into cassettes (15 kg weight drills) and fed to the first quenching for heating in a 100% BaCig bath with a temperature of 1100 ° C and held for 2 minutes 30 seconds. After this time has elapsed, the transfer of the line takes the cassette out of the bath for 5 s into the space where the drills are hardened in an air stream at an overpressure of 5 atm, with a small water supply turning into fog for 2 minutes 30 seconds.

The process is then carried out according to the following process:

heating at 1100 ° C for 2 min 30 s in a bath of composition 100%, transfer to the final heating bath for 5 s;

final heating at 1225-1240 ° C for 2 minutes 30 seconds (temperature corrected by the grain score) in a 100% bath of BaCla;

transfer to the quench bath of composition 255 35% BaCl250-55% CaC, the rest NaCl (salt NT 495) for 2 min 30 s;

cooling the drills with compressed air to the temperature of the workshop for 10 minutes;

tempering in salt 100% HT 3 495 at 600+ 0 -5 ° С

cooling the drills with compressed air to the temperature of the workshop;

tempering in salt 100% HT 495 at 600 ° C + 5 ° C for 10 minutes;

cooling with compressed air + water;

washing off.

As studies show, quenching drills in water, although it gives an increase in hardness of 2-3 units, leads in part to the formation of microcracks on the ribbons. After the heat treatment and the completed process, the drill is subjected to stochastic tests.

The tests are carried out on steel blanks 45 with a hardness of 169-220 NOT with cooling with a 5% emulsion. Drilling is carried out at a speed of 475 rpm, a depth of 80 mm and a feed of 5 0.4 mm / min. The geometrical parameters of the drills comply with the technical conditions. For the criterion of resistance, they take full dulling and creak

The test results of drills for cutting are shown in the table.

Hardening according to the 2nd mode leads to partial chipping of the edges, a decrease in the heating temperature from 1120 ° С to 1050 ° С 5 (mode 4) reduces this phenomenon.

Improving the cutting properties of drills from steel R6M5 provides a higher redness due to the alloying of the solid solution under the recommended modes. The test results show that the resistance increases by 2 times.

The economic effect due to the increase in tool life is 0.5 million rubles.

Conditions

Mode

Persistence

Solubility of alloyed holes in solid solution

Factory mode (fully compliant with specifications)

Hardening in air-water flow from temperature, for 3 minutes, then factory mode

Quenching in air flow from a temperature of 1100 C, holding 3 min, then the factory mode

Hardening in air-water flow from temperature, delay 3 min, then factory mode

Cz

W

200

3.26

0.18

223

3.42

0.38

403

3.32

0.21

343

3.36

0.32

Claims (2)

1. METHOD FOR THERMAL PROCESSING OF TOOLS FROM QUICK CUT STEEL, including the first hardening from a temperature lower than the accepted one, the second standard hardening and tempering, characterized in that, in order to increase wear resistance, the first hardening is carried out from 1100–1120 ° С with cooling in the air stream. 2. The method according to π. 1, characterized in that the shutter speed during the first hardening is carried out for 3-5 minutes.