SU1281596A1 - Method for hardening surfaces of metal components - Google Patents

Abstract

The invention relates to the thermomechanical processing of metal parts and can be used in mechanical engineering. The goal is to increase the productivity of the process and increase the depth of the hardened layer. The surfaces of the parts are heated in pairs by friction with a specific pressure of 25 ... 35 MPa up to the temperature of Ac, diluted and cooled. At the same time, the treated surfaces are strengthened to a depth of 1.0 ... 1.6 mm for steel parts and up to 1.2. ..2.0 mm for cast iron parts. 1 tab. (

Description

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SP

with a

one

The invention relates to the thermomechanical processing of metal parts, namely their end surfaces, and can be used in all areas of mechanical engineering to increase hardness and wear resistance, for example, shut-off parts of pipeline fittings: saddles, gate valves, wedges, etc.

The purpose of the invention is to increase the productivity of the process and increase the depth of the hardened layer.

Example. Reinforced, saddles behind-ЗМС1-65х21 (В „65 mm, Рр 21 MPa) of oil and gas fittings. The experiments were carried out during friction heating.

12815962

ring specimens (D

D

 65 mm) of steel

fO

15

30X13 and MF 28 cast irons. Friction heating is performed by friction welding at 750 h / min and pressure of 25 heating surfaces for 6–8 s and for cast iron 12 they stop after the temperature reached and the friction temperature is 950-1200 ° C. .

The results are processed in the table.

ring specimens (D

D

bunk

80 mm.

 65 mm) of steel 40HN, 20X13,

30X13 and cast iron MF 2848 and HF 45-5. Friction heating is performed on a friction welding machine at a rotational speed of 750 rpm and a pressing pressure of rubbing surfaces of 2535 MPa, with a heating time for steels of 6-8 seconds and for cast irons 12-14 seconds. The heating is stopped after reaching the established temperature of the surfaces of the friction 950-1200 ° C. The samples are cooled immediately after dilution with watering.

The processing results are shown in the table.

Note: Initial hardness, HB: steel 40HN 194-241, steel

20X13 197-219, cast iron B4 45-5 170-207. The initial non-flatness is about 1 mm.

As can be seen from the table, the achievement of the process of thermomechanical processing

effective hardening of the support surfaces according to the proposed method only with certain opto-op. At lower values (10 minimum values of the specific 19 MPa) specific non-depletion pressure (25-33 MPa), effective surface heating is feasible during friction, and therefore the necessary surface hardening effect is not achieved, since the surface hardness does not change much compared with the original and significantly lower achievable with, processing with specific pressure in the optimal range.

At higher values of specific pressure (36-50 MPa), there is a strong heat generation and warming up of a large amount of metal, increased wear of the rubbing surfaces during processing (slump of parts) and increased flatness, Because

The results of studies of the samples show that with the proposed method, the following hardness values are obtained for hardened 5 friction surfaces, HRC: from steel 40ХН 48-58; 20X13 51-53; 20X13 51-53 30X13 52-54; from HF 45-5 cast iron, 52-64 cast iron, СЧ28-48 54-61 with a depth of 1.0–1.6 mm for the steel layer and 1.2–2.0 for the cast iron.

On samples subjected to friction by a known method, the surface hardness for all steels is no more than 36 HRC, and for cast irons - 10

7 - ---- With this, the effectiveness of reinforcement - is reduced to 38 HRC with a depth of reinforced workpiece of the machined end surface of not more than 0.1 mm. This is due to a decrease in the locality of their heating during friction, heating.

more metal and extrusion

-20

25

thirty

heated metal from the slit joint to the burr with increased draft of parts. This leads to a decrease in the intensity of cooling of the surfaces processed by the proposed method and a decrease in their hardness, i.e. reduce the effectiveness of hardening. In addition, the increased flatness resulting from the intense wear of the rubbing surfaces leads to a deterioration of the macro-geometry of the surfaces to be machined.

Thus, it can be seen that surface hardening is provided only at specific pressure of 25-33 MPa.

In a known manner, the surface 35 of the part is heated by friction by moving the steel hardened roller at a speed of up to 120 m / s relative to the surface of the part with their mutual pressing. When this occurs, the quenching of the friction heated layer due to cooling by heat inward occurs. Parts.

With a large depth of the layer hardened by the proposed method, the wear resistance and durability of parts is increased. The shallow depth of hardening in the known method does not allow the finishing treatment of the hardened surface, which is required, in particular, for saddles of gate valves.

The proposed method differs from the known one due to its greater productivity due to the mutual pairwise yn-i reinforcement and the greater depth of the hardened layer.

Claims (1)

Invention Formula A method of hardening the surfaces of metal parts, including heating by friction with subsequent dilution of the rubbing surfaces and cooling, characterized in that, in order to improve the process performance and increase the depth of the hardened layer, heating is performed by the pairwise friction of the hardened surfaces at specific pressures of 25-35 MPa. 15964 The results of studies of the samples show that with the proposed method, the following hardness values are obtained on surfaces hardened by 5 friction, HRC: from steel 40ХН 48-58; 20X13 51-53; 20X13 51-53; 30X13 52-54; from HF cast iron 45-5 52-64; cast iron СЧ28-48 54-61 with a depth of hardened layer of 1.0-1.6 mm for steel and 1.2-2.0 for cast iron. On samples subjected to friction by a known method, the surface hardness for all steels is no more than 36 HRC, and for cast irons - 10 7 - ---- Row 38 HRC with a depth of the hardened layer of no more than 0.1 mm. With a large depth of the layer hardened by the proposed method, the wear resistance and durability of parts is increased. The shallow depth of hardening in the known method does not allow the finishing treatment of the hardened surface, which is required, in particular, for saddles of gate valves. The proposed method differs from the known one due to its greater productivity due to the mutual pairwise yn-i reinforcement and the greater depth of the hardened layer. Invention Formula A method of hardening the surfaces of metal parts, including heating by friction with subsequent dilution of the rubbing surfaces and cooling, characterized in that, in order to improve the process performance and increase the depth of the hardened layer, heating is performed by the pairwise friction of the hardened surfaces at specific pressures of 25-35 MPa.