SU981400A1 - Method for treating tools from high-speed steels - Google Patents

Description

one

This invention relates to the manufacture of tools for high-speed steels,; in particular, to machining of tools that have undergone final mechanical processing after quenching and tempering.

It is known the use of low "1 temperature". chemical heat treatment processes (at 550-56 SUS) cutting tool short-cutting high-speed steels after quenching, tempering and final grade & fucking with sharpening jTlJ.

These methods increase tool wear resistance, but at the same time lead to increased brittleness of the surface layer. This is due to the formation of an em in a layer of a fragile surface zone containing excess E j phases and especially with a high fragility along g facets of grains due to a higher Concentration of the fragile phases.

There is a known method for reducing the brittleness of the nitrated layer, which consists in diluting ammonia with nitrogen or argon.

However, the application of this method increases the cost and complexity of the process, without altering the resistance to wear, and slightly reduces brittleness.

The closest to the proposed technical essence and the achieved result is a method of processing a tool from high-speed steels, including quenching; tempering, machining, nitrocementation at 55 ° C at 580 ° C for 6-8 hours, after which they are machined at a depth of 0,02,03,03 mm.

The application of this method also

15 it complicates and increases the cost of treating the cutting tool from high-speed steels due to the use of Veicoumnost tempering and additional final machining,

20 increases the carbonitriding time to 6-8 hours.

Claims (3)

In addition, the tool processed by this method has insufficient wear resistance due to the adverse effect of the microrelief of the surface on the trash process during the operation of the yen structure. The disadvantage should also include the increased fragility of the grain boundaries compared to the weight of grain. The aim of the invention is to reduce brittleness, increase wear resistance, and increase the purity of the working surfaces of the tool. This goal is achieved by the fact that according to the method of machining the tool, which includes quenching, hard start, machining, and short-heat treatment at 550-580s, surface chemical deformation is performed before the chemical heat treatment. Moreover, the depth of the surface deformation is set to not less than the thickness of the diffusion layer, and the deformation npi is given by the indenter, which oscillates with the ultrasonic frequency when the oscillation is 5-60 µm by applying cellular terrain. In the process of surface plastic deformation of the surface, its microrelief changes. The relief after grinding is completely changed. So-called scallops are eliminated, the height of asperities is reduced. In the process of numerous strikes of the indenter, which oscillates with a sonic frequency, a cell is formed on the surface of the arm, approximately copying the shape of the indenter. The sequential displacement of the indenter over the entire surface to be treated forms a cellular relief. In order to obtain cellular relief, the indenter oscillation amplitude should be within 5-6 Om, and displacements of the indenter relative to the surface to be treated should ensure continuous filling of the entire surface area with cells. The brittleness of the surface layer is reduced by increasing the radii of curvature of the peaks and valleys of asperities, along with decreasing them. Increasing the radius of curvature of the peaks of asperities contributes to reducing the concentrations of diffusing elements in them, thereby reducing the number of brittle phases formed. Increasing the radius of the micron-irregularities eliminates the concentration grating of stresses. In the process of surface plastic deformation, the grinding of the grain occurs with simultaneous fragmentation of the blocks. Subsequent chemical and heat treatment results in more uniform saturation of the surface volumes of meta; saturating elements (due to a sharp increase in the number of paths of enhanced diffusion (grain boundaries and blocks). The size of the fragile brittle ones is also reduced. Increased wear resistance occurs as a result of an increase in the bearing surface in contact with the workpiece, an increase in the hardness of the surface layer due to the crypt and separating more dispersed phases in the process of chemical heat treatment, as well as by reducing the number of microsections of the surface layer, which cause catastrophic wear. This microrelief on the surface provides better lubricant retention, which also helps to reduce wear.The method is tested in the preparation of calibrating spline piercings and slit seals made from steel R6M5. Example: Calibrating spline firmware from steel RvM5 after quenching from ± 225 ° С and threefold tempering at 56 ° C for 1 hour is polished over the outer diameter to a final size of 60.2 Ohm. The hardness of the surface layer is 63 HRC. After that, the teeth calibrating the teeth are machined on the outer diameter with a spherical 0-5 mm indenter, oscillating with a frequency of 18 kHz and an amplitude of 15 µm, installed in the cutter of the turning machine. Linear velocity of the flashing surface relative to the indenter of the MH m / min, transverse displacement 0, O9 mm / rev. Reinforced firmwares are subjected to gas carbonitriding for 2 hours, while the depth of the layer is 40 microns, the microhardness of the surface layer corresponds to 1044-1098 kgf / mm². The stability of the firmware corresponds to .810 parts. I1C is manufactured and processed by a batch of firmware from steel P6M5 according to the modes of the prototype: quenching from 1225 ° C and tempering of Sp X 560 1 h. The hardness is 63 63 HRC. After heat treatment, the piercing is grinded to an outer diameter of 60.24 mm, and then subjected to gas nitropementatl at 56 ° C in an IJW5 furnace for 6 hours. Then, tempering is carried out at a vacuum of 4-10 mm Hg for 7O min. Solder c is formed on the surface; The microhardness of "946-1002kgs / mm Topshia SPo is. 100 microns After carbonitriding and tempering, the firmware is subjected to a final mechanical fit to size 6O, 20 mm. Firmness of firmware is 330 parts: her. Thus, the resistance of the proposed option in comparison with the prototype increases 2.4 times. Firmness of firmwares from R6M5 steel, subjected to quenching and tempering to a solidity of 63 HRC is 200 parts. An analysis of the surfaces of the nasal, the tested firmware shows that processed by the proposed method does not have brittle fracture traces, while the firmware processed according to the prototype mode have brittle chipping of the diffusion layer over an area of 4% of the working surfaces. Claim 1. Method of processing high-speed steel tool, including quenching, 66 ku, tempering, machining and chemical-heat treatment at 550580 ° C, characterized in that, in order to increase operation. tool durability, surface chemical deformation is performed before chemical and thermal treatment. 2. A method according to claim 1, characterized in that the surface plastic deformation is carried out to a depth not less than the thickness of the diffusion saturation layer. 3. A method according to claim 1, characterized in that the surface plastic deformation is induced by an independent one, oscillating with an ultrasonic frequency with an oscillation amplitude of 5160 microns. 4. Method pop. 1, characterized in that the plastic deformation is carried out by applying a cellular relief. Sources of information taken into account in the examination 1. Yu.A. Geller. Tool steel. M., 1975, p. 493-503. 2. Lahtnn Yu.M. and others. Nitriding of steel. M., Mechanical Engineering, 1976, p. 119. 3. Authors certificate of the USSR 765379, cl. C 21 D 9/22, 1980.