Production of disc forgings from heat-resistant nickel and titanium alloys. Stampings from corrosion-resistant, heat-resistant and heat-resistant steels and alloys. General technical requirements Articles on stamping heat-resistant alloys

Incomplete hot deformation from hot is different:

1. Possibility of manufacturing forgings of increased accuracy (8 ... 10 grade) with high surface quality (Ra = 2.5 µm; Rz = 20 µm) and with improved mechanical characteristics (strain hardening, depending on chemical composition alloy and deformation conditions is 20 ... 150% of the initial yield strength);

2. High technical and economic indicators (the metal utilization rate reaches 0.68 ... 0.95, the labor intensity of subsequent cutting is reduced by 25 ... 75%);

3. Decrease in the level of technological cost of stamped forgings due to lower heating costs and the virtual absence of metal losses as a result of scale formation;

4. Improving the performance of parts made of stamped forgings as a result of the formation of a favorable macro- and microstructure of the forging.

Compared cold formed incomplete hot is carried out with the application of lower specific deforming forces, which leads to an increase in the durability of the working parts of the die tooling, the possibility of making forgings from higher-strength steels and alloys, and the use of forging equipment of lower power.

Under conditions of incomplete hot deformation, the ductility of metals and alloys is higher than under cold deformation. This reduces the number of punching transitions.

The most widespread forging under conditions of incomplete hot deformation is for the manufacture of forgings from medium-carbon and heat-resistant steels, titanium alloys.

Sheet stamping

In sheet stamping, the original blank is a sheet, strip or strip, rolled into a roll, obtained by rolling, having a constant thickness.

Sheet stamping can be used to produce both flat and spatial blanks, which are usually subjected to minor subsequent machining, and in some cases they can go to assembly without machining. The technological process of sheet stamping usually consists of a number of operations and transitions carried out in dies. Stamps are devices containing a working tool that carries out a given shaping of the workpiece, as well as guides that fix fasteners. The stamps are fixed in the working elements of the press, hammer or other machine - tool. The complexity of the design, and, consequently, the cost of the stamp depends on the serial production and determines the feasibility of manufacturing parts by sheet stamping. The cost price of blanks obtained by sheet stamping is mainly determined by the cost of the metal consumed and the share of the stamp cost per stamped part. The number of operations and transitions, and, consequently, the duration of the technological cycle of stamping is determined by the complexity of the configuration of the stamped part and the requirements for dimensional accuracy and cleanliness of its surface.

Table 10

Technical data of model 8552 cut-off machine.

The abrasive material is selected depending on the type of metal being cut. For cutting steels or high-temperature alloys, electrocorundum wheels are recommended. The grain size is selected depending on the operating mode and the required roughness and accuracy of the cut surface. For cutting steels, circles with a smaller grain are used than for non-ferrous metals. The hardness of the wheel should be such that, during operation, abrasive grains crumble as they dull, new cutting edges are formed and new grains are exposed. Advantages of abrasive cutting: high geometric accuracy and low roughness of the surface, cut (R a = 0.32 - 1.25 microns), the ability to cut high-strength metals of any hardness, high productivity.

4.7. Heating of blanks for stamping

The processes of forging and stamping, carried out at high temperatures, can be considered as joint processes of metal forming and thermal impact on them. Thermal effects on the metal leads to the loss of its elastic properties, a significant decrease in its resistance to deformation and to a sharp increase in plasticity. In the process of hot OMD, the emerging stresses are relieved, in particular, during the return and recrystallization of the metal.

The optimal punching mode should provide the necessary conditions for a successful process, as well as high quality forgings, in which the harmful effects of heat are limited. Therefore, the thermal regime is developed for each alloy, taking into account the initial structure of the metal, its volume, the ratio of the dimensions of the workpiece and the purpose of the forging. One of the main tasks in development technological process is the determination of the appropriate temperature range, i.e. the temperature of the beginning and end of metal processing. For the right choice temperature interval, the following factors must be taken into account:

- The metal must be pressure treated in the temperature range of maximum ductility. For this purpose, plasticity diagrams were constructed for most alloys, which are a set of temperature dependences of the strength and plastic characteristics of the alloy.

The metal must be deformed in a state corresponding to the region of the solid solution of the alloy without the slightest signs of overheating or overburning, and it is desirable to complete the deformation at temperatures such that secondary phase transformations do not occur. For these purposes, an analysis of the alloy state diagram is used.

Deformation should be carried out at temperatures such that the structure is refined rather than grain growth. This information is established by analyzing the recrystallization diagram of the alloy.

For the EI868 alloy, the temperature range for hot forging is from 1130 to 1150 ° C. For the EI868 alloy, it is recommended to use heating in an electric furnace. Electric heating in terms of energy consumption per ton of billets is less economical than heating in flame furnaces. However, it is widely used, since it increases labor productivity, allows full automation and ensures high process stability, improves working conditions and reduces metal losses due to scale formation.

The loss of metal in the form of scale during heating in electric resistance furnaces is 0.2 - 0.4% of the mass of the heated metal, which is almost ten times less than when heated in flame furnaces. Reducing the scale improves the quality of the forgings and increases the life of the dies of the press-forging equipment. The technological advantages of electric heating devices are especially effective in batch production.

In this technological process, it is proposed to use a rotary heating furnace of electrical resistance, the temperature in the furnace is 1140 ± 5 0 С, the number of blanks in the furnace is 50 pieces. The heating time of one charge is about 1.15 hours when heating the furnace or 0.3 hours when working with a preheated furnace. The temperature in the furnace is monitored using an optical pyrometer M90 - P1 with a record in a special journal. Table 12 shows the technical characteristics of the rotary heating furnace.

Table 12

Technical characteristics of the electrical resistance furnace.

4.8. Hot die forging

4.8.1. Determination of the required press force and selection of technological equipment

In the new version of the technological process, stamping is carried out on a screw friction press. The free running of the friction press allows the metal in each die strand to be deformed in a few strokes. The fractional deformation achieved in this case can be even greater than the deformation of the equivalent crank hot stamping press. The possibility of using the lower ejector significantly expands the range of stamped products and allows you to work with small stamping slopes, and in vertically split dies - even without slopes for cavities "falling into the split plane. Friction presses have relatively great speed deformation in comparison with other presses, however, the flow of metal during stamping on these presses is similar to stamping on other presses. In recent years, friction presses have been significantly modernized, they have become more high-speed, and in some designs, a good direction of the slider is made, which allows stamping in multi-strand dies. In this case, two parts are stamped at once. Table 13 shows technical specifications friction press.

Determine the required effort of the press.

Table 13 shows technical specifications friction press recommended for hot die forging.

Table 13

Technical characteristics of the screw friction press.

4.8.2 Manufacturing technology of the stamp and materials for manufacture of stamps

Hot forging dies operate under very tough conditions. They are exposed to repeated high voltages and temperatures. Intensive flow of hot metal over the surface of the die causes abrasion of the groove, as well as additional heating of the tool. On the surface of the stream, so-called hot cracks are formed. Therefore, die steels must be distinguished by high mechanical properties, combining strength with impact toughness, wear resistance, heat resistance and maintain these properties at elevated temperatures.

Materials for dies should be well annealed during heat treatment and processed on metal cutting machines. It is desirable that the die steel does not contain scarce elements and is cheap.

(28) Priority of the State Committee of the USSR for nzooretekny and open (72) Authors of the invention Production Association "Leningradskiy metal plant (54) METHOD OF PRODUCING STAMPED PRODUCTS FROM HEAT-RESISTANT STEELS. alloys, for example, turbine blades and disks. There is a known method of manufacturing products for heat-resistant steels and alloys, including heating the workpiece to the temperature of hot deformation, preliminary stamping, heating and final stamping (in particular, on a hammer) with a degree of deformation of 3-10%) 11 The disadvantage of the known method (when stamping on a hammer) is the low quality of products due to the difficulty of ensuring a given size of the austenite grain of the metal of the product. given size austenite grain. The aim is achieved by the fact that the intervals between hammer blows during the final stamping are 0.5 - 10 sec., the total duration of final stamping is 8 - 35 sec., and the total degree of deformation of the workpiece during final stamping exceeds the range of critical degrees of deformation by 2 - 15%, Obtaining a given size of austenite grain in products stamped on hammers is associated with the need to ensure such temperature-time parameters of 1 stamping (different for different brands steels and alloys), which would provide the possibility of obtaining the total deformation for several hammer blows as the sum of deformations for individual blows, i.e. so that in the intervals between the hammer blows, at the selected deformation temperatures, the processes of recrystallization of treatment, removing the hardening from the previous deformation, do not have time to proceed. upper limits The time interval between impacts is determined by the value of the excess of the temperature of the deformed workpiece in the time interval between impacts relative to the processing recrystallization threshold for the selected alloy (steel) grade and the range of degrees of metal deformation in different parts of the workpiece per hammer. Wherein minimum value time interval (0.5 sec) refers to the case when the temperature of the end of the previous deformation (on the metal of the workpiece) exceeds the threshold of recrystallization of processing by a maximum value (180-200) C. To achieve this, the value of the relative deformation of the workpiece during the precursor blow must be extremely large (4 - 5)%. The maximum value of the time interval (10 sec) refers to the case when the value of the relative deformation of the workpiece for the previous blow was minimal (1%), and excess. temperature preceding deformation with respect to the processing recrystallization threshold was minimal (20 - 30). critical degrees of deformation with a decrease in the temperature of the end of deformation and, in connection with this, an increase in the probability of individual sections of the workpiece falling into the zones of critical degrees of deformation at the same total values ​​of deformation; 3) an increase in the probability of obtaining an unacceptably large grain in zones of the workpiece with a hindered metal flow, (where rel. deformation is significantly lower than the average (calculated) in the selected section of the workpiece), since in these zones the preparatory stages of the recrystallization th duration of the stamping cycle, the process of recrystallization of finishing in these zones can begin before the end of stamping, i.e. in this case in these zones total deformations will not be equal to the sum of partial deformations for all hammer blows, which means that the total deformation in these zones may not be supercritical, which will lead to the appearance of unacceptably large grain in these zones, 733828 4 10 15 20 25 ЗО З 5 40451Я55 Numerical limits of the total duration of the stamping cycle obtained experimentally on high-temperature alloys of the type N 65 VMTI (EI - 893) for different temperatures and degrees of deformation. Thus, a new positive effect created due to the introduction of the indicated time intervals is associated with the provision of obtaining a given size of austenitic grain when forging workpieces made of heat-resistant steels and alloys on hammers for several impacts. recrystallization of the metal of stamped blanks fails to proceed during deformation, the metal of the blanks is strengthened during deformation, and therefore the resistance of the blanks to deformation increases significantly with an increase in the relative deformation. In this regard, to ensure the possibility of stamping blanks of maximum dimensions with a given size of austenite grain, the general deformation during the manufacture of blanks is distributed between preliminary and final stampings so that during final stamping the value of relative deformation throughout the volume of the blank (taking into account its uneven distribution) is at the level of minimum values ​​of the critical degrees of deformation (5 - 20)% for various grades of heat-resistant alloys and steels, i.e. (2 - 15)% exceeding the range of critical degrees of deformation) During the final stamping, the relative deformations obtained in the workpiece and individual hammer blows are summed up and constitute a supercritical value (5 - 20)% for the entire stamping cycle. rest, polygonization and the initial stages of the process of recrystallization processing. However, the areas occupied by newly formed recrystallized grains during the intervals between impacts should not exceed the areas corresponding to the maximum acceptable size grains. At the same time, for various grades of high-temperature alloys and steels and various actual temperatures of deformation, the time intervals between impacts should not exceed (0.5 - 10) sec, and the total duration of final stamping should not exceed (8 - ZUy sec, After final stamping, due to unacceptable a long time interval between stamping and straightening, in order to avoid the appearance of coarse grains during subsequent heat treatment, they perform combined trimming of the flash and straightening on a trim press, in which additional small (critical) deformations (displacement of metal in the flash) along the body of the workpiece are practically eliminated. hard billets 33828 6 austenitic grain size, as a result of which the service life of products, for example, blades, approximately 2 times increases. State Committee USSR for inventions and discoveries 13035, Choskva, Zh, Raushskaya nab., 4/5 Branch of the PPP "Patent", Uzhgorod, Proektnaya st., 4 5 7 woks, which are not subject to unacceptably large warpage during normal (uncombined) pruning flash on edging presses, after the final stamping, the usual trimming of flash on an edging press is carried out without after. the next edit. Experimental stamping of billets of turbine blades IE alloy EI - 893 / KhB 65 V 9 M 4 YuT 730 mm long and 30 kg in weight was carried out. The billets were heated to a temperature of 1150 C, pre-stamped on a stamping hammer with a mass of 25 tons falling: parts in several blows hammer in the temperature range (1000 - 1140) C, with under-stamping, providing the relative deformation along the workpiece body in the range of (8 - 20)% during the final stamping, was cut off on the workpieces by flashing on a trim press. Then the workpieces were heated to a temperature of 150 C, and finally stamped on the same hammer for 5 - 6 blows with intervals between blows (- 5) sec and the total duration of the stamping cycle (15 - 20) sec. The size of the austenite grain obtained in stamped products was mainly within the range of 0.8 mm, individual grains up to 1 mm, with an allowable grain size of 1 mm. stamping of large-sized products with a given Formula of the invention A method of manufacturing stamped products from heat-resistant steels and alloys, including heating the workpiece to the temperature of hot deformation, preliminary stamping, heat the final hot stamping for several hammer blows, heat and heat. , that, in order to improve the quality of 15 products by providing a given size of austenite grain, the intervals between hammer blows during the final stamping are (0.5 - 10) sec., the total duration of the final stamping is (8 - 35) sec, and the total degree. deformation of the workpiece during final stamping exceeds the range of critical degrees of deformation by (2 -15)%. Sources of information taken into account in the examination 1. Mayevsky IL Processing by pressure of ZO, heat-resistant alloys, M., 1964, p. 30 - 32, 46,115 - 117.2, Forging and stamping production magazine, 1977, U 5, p. 22 - 23 (prototype),

Application

2512647, 01.08.1977

PRODUCTION ASSOCIATION OF TURBO CONSTRUCTION "LENINGRAD METAL PLANT"

NEMIZER YURI AIZIKOVICH, SHOBOLOV PETER ALEXANDROVICH, MKRTYCHYAN ZORAB ANTONOVICH, CHIVIKSIN YAKOV EFIMOVICH, PAVLOV ANATOLY FEDOROVICH, SAVINOV AVENIR MIKHAILOVICH AVENIREVICH

IPC / Tags

Reference code

A method of manufacturing stamped products from heat-resistant steels and alloys

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