Method of production of difficult to form forging of high-alloy steels and alloys

FIELD: metallurgy.

SUBSTANCE: invention relates to production of forgings of high alloy nickel-based steels and alloys which are difficult to form. According to proposed method, ingot is placed without preliminary roughing into furnace heater up to 400. Ingot is heated in heating furnace first to 600±10°C at rate not exceeding 50°C/h and is held at this temperature for 1.5-2.5 h. Then ingot is heated to 700±10°C at rate of 50°C/h maximum and is held at this temperature for 0.8-1.2 h. Heating of ingot to forging temperature of (1150-1180)±10°C is carried out at any rate, and ingot is held at this temperature for 3-5 h.

EFFECT: increased yield of ready metal and getting of fine-grained structure, provision of high level of mechanical properties and adaptability to further processing of forgings.

4 cl, 1 ex

 

The invention relates to metallurgy, in particular to the technology of production of forgings made of high-alloyed steels and alloys, mainly on the basis of Nickel, which is hard. At the same time to ensure a high level of mechanical properties and processability further processing, forgings must have fine-grained structure with a grain size of not more than 4 points.

A known method of heating ingots for forging, which consists in loading the ingot in the furnace after reaching its temperature, the maximum allowable to maintain the continuity of the heated ingot, and the temperature rise of the working space of the furnace is produced at the moment of reaching the greatest temperature difference between the surface and the Central zone of the ingot. The determination of the moment of achieving the greatest difference in the cross section of the heated ingot is produced on the charts and nomograms changes in thermal field of the ingot before landing in oven, built for forgings, components of the nomenclature of production workshop (1).

The disadvantage of this method is that this heating step maloplastichnye steels and alloys in the temperature range 700-800°promotes the formation of internal stresses and delamination, which can lead to zabrakovku metal, and does not take into account the increase of plasticity as about the roar of the ingot.

Also there is a method of forging castings, which consists in forming on the edges of the blanks of projections and depressions in the deformation process and the change of direction of the subsequent passage relative to the previous with the casting-off of the workpiece 90°and to improve the quality of the forging of rectangular cross-section through the intensification of deformation of cast metal structure of the Central zone and brewing internal defects, the tabs on the sides of the workpiece during deformation is formed in a checkerboard pattern and the workpiece after each pass slip relative to the strikers on half the distance between the projections (2).

The disadvantage of this method is the probability of powstawania crests of the waves and especially the corners of the workpiece, which can lead to the formation of flaws and the need for intermediate sweeps and, as a consequence, the decrease of yield.

The known method of heating billets for forging, namely, that the workpiece is placed in a heating furnace, and stand before reaching the surface layers of the workpiece forging temperature, remove it from the oven and stand in the air before reaching the surface layers of the workpiece temperature, which had a Central layers when removing it from the oven, and then place the workpiece in the furnace. While improving the quality of the surface layers zagotovka is achieved by reducing the intensity of grain growth during heat treatment. (3)

The disadvantage of this method is the possibility of formation of internal cracks and delamination due to the tensile stresses that occur during heating of the metal without limiting the heating rate of the alloys based on chromium. Also the disadvantage of this method is the increased consumption of gas due to intermediate podstugivaniya metal in the air.

The closest analogue of the claimed invention is a method of heating and deformation of Nickel-chromium alloys, described in (4), including:

- heating peeled bars on mode:

landing ingots in a furnace at a temperature of not more than 600...700°and holding at that temperature for 1 hour;

temperature rise up to 1160 1180...°C for 8 hours, holding at that temperature for 3...4 hours;

forging in a flat, cut-out or combined strikers with intermediate heating and final heating in the destination profile (3, process flow diagram, pp.232);

- air cooling.

Signs nearest analogue, coinciding with the essential features of the claimed invention: heating of the ingots in furnaces with Posada at a temperature not exceeding 600°C, holding at a temperature of tenements at least 1 hour, gradual climb up to forging temperature, holding at the forging temperature 3...4 hours, subsequent forging in cut b is icah with intermediate heat treatment, air cooling.

The disadvantages of this method are:

- the possibility of formation of internal cracks and delamination in the process of heating ingots due to the lack of excerpts in a heating furnace at temperatures of 600°700°required for full heating of the ingot cross section in the interval of temperatures abrupt changes in thermal coefficient of linear expansion;

- obtaining coarse-grained structure due to the operation of the heating forgings in end profile, which reduces the level of mechanical properties and processability further processing.

The problem to which the invention is directed, is to increase the yield, and obtaining fine-grained structure to ensure a high level of mechanical properties and processability further processing of forgings.

The problem is solved in that a method for the production of hard-forged from high-alloyed steels and alloys, including landing ingot metal without pre-Stripping in a preheated heating furnace, heating the ingot in said furnace and holding at that temperature, heating the ingot to forging temperature with exposure at this temperature, forging with intermediate cleaning and air cooling, while the landing of the ingot metal implement Aut in the heating furnace, preheated to 400°±10°, ingot heating furnace is first heated to a temperature of 600°C±10°With a speed of no more than 50°per hour and maintained at this temperature for 1.5-2.5 hours, and then to a temperature of 700°±10°With a speed of no more than 50°With in the hour and kept at this temperature for 0.8 to 1.2 hours, heating the ingot to forging temperature, which is (1150-1180)±10°To produce with arbitrary speed, and exposure at this temperature is carried out for 3-5 hours, and before the final removal of the forging of the head and bottom parts of the ingot otkalyvayut axle, Raskov cut in half and produce the final forging each half separately with the subsequent removal of pins, and the forging of the ingot is carried out by precipitation, while before the draught from the head part of the ingot otkalyvayut trunnion, forging the ingot is carried out by scrubbing with a degree ukawa not less than 3 to cut the strikers on a circle-a circle with compression in one take-away is not more than 20 mm in the first passages.

The exception operations pre-Stripping allows you to save the fine-grained surface layer, which will reduce the likelihood of cracking during deformation of alloys, especially in the first cones. This is the purpose of limiting the compression over the course of the press is not more than 20 mm in the first takeaway.

Aging in a heating furnace at temperatures of 600°700°it is made for full heating of the ingots in the temperature range of abrupt changes in thermal coefficient of linear expansion with the aim of elimination of internal tension cracks. Excerpt of less than 1.5 hours at a temperature of 600°and 0.8 hours at a temperature of 700°inefficient, as it does not lead to heating of the ingot. The shutter speed more than 2.5 hours at a temperature of 600°and 1.2 hours at a temperature of 700°irrational, as it leads to useless fuel consumption in the furnace.

Forging axle before upsetting of the head portion of the ingot facilitates shrinkage sink in the journal, which will increase the yield, as will preclude the development of shrinkage cracks in the body of the ingot in the process of precipitation.

Forging axle from the head and the bottom part of the ingot, followed by rozrobka Raskova in half and with the final otkolom each half separately with the subsequent removal of the pins will allow you to obtain a uniform fine-grained structure, as it will eliminate the last of heating in the final profile for odowa second end, retromania Raskova and remove the head and bottom trimmings.

Example execution:

1. Technology prototype.

Ingots with a diameter of 400 mm of Nickel-based alloys were put in a heating oven, preheated to 400°and was heated by mode is:

- extract at 400°C for 2 h;

- heating at 50°C/h to a temperature (1150±10)°C;

- the shutter speed when the forging temperature for 4 hours;

The ingots were forged on pig billet diameter CR-325 mm for precipitation on washers, kV mm for hammers, forging a diameter of from 225 to 305 mm 4-6 cones depending on the destination profile, with individual reductions of up to 20 mm per turn of the press in the first stems and up to 50 mm thereafter. The last transition in the forging forgings produced from the heated end profile with rozrobka in half.

Through the technology of heating and forging predeterminado and controlled 315 forging alloys. 27 forgings detected internal defects and areas of nedefitsitnost.

2. The proposed technology.

Ingots with a diameter of 400 mm of Nickel-based alloys were put in a heating oven, preheated to 400°and was heated by mode:

- extract at 400°C for 2 h;

- heating at 50°C/h to 600°C;

- exposure at 600°C for 2 h;

- heating at 50°700°C;

- exposure at 700°C for 1 h;

- heating up to temperature (1150±10)°C;

- the shutter speed when the forging temperature of not less than 3 hours and not more than 5 hours

The ingots were forged on pig billet diameter CR-325 mm for precipitation on washers, kV mm for hammers, forging diameter of the t 225 to 305 mm 4-6 cones depending on the destination profile, with individual reductions of up to 20 mm per turn of the press in the first stems and up to 50 mm thereafter. Forgings forged with the preliminary draft up to diameter 420-460 mm after odowa studs from the head part of the ingots, pig workpiece without precipitation. The last transition in the forging forgings produced without heating in the final profile after odowa pivots and cutting in half.

Through the technology of heating and forging predeterminado and controlled by more than 200 forging alloys. Internal defects and areas of nedefitsitnost not found. The yield increased by 10-12% compared with the technology of the prototype. The level of mechanical properties in comparison with the technology of the prototype has grown on average by 10...15%.

Sources of information

1. A.S. No. 728968, CL 21 J 1/06, etc. 10.05.78,

2. A.S. No. 963661, CL 21 J 1/04, etc. 22.01.81,

3. A.S. No. 897372, CL 21 J 1/06, etc. 23.04.80,

4. Dzugutov ME, Ductility and deformability of high-alloyed steels and alloys, M., metallurgy, 1990, str-232..

1. Method of manufacturing hard-forged from high-alloyed steels and alloys, including landing ingot metal without pre-Stripping in a preheated heating furnace, heating the ingot in said furnace and holding at that temperature, heating the ingot to forging temperature with exposure at this temperature, forging with intermediate Stripping and cooling gap is giving in the air, characterized in that the planting of the ingot metal is carried out in a heating furnace, heated to 400±10°, ingot heating furnace is first heated to a temperature of 600±10°With a speed of no more than 50°per hour and maintained at this temperature for 1.5-2.5 h, and then to a temperature of 700±10°With a speed of no more than 50°per hour and maintained at this temperature within 0.8-1.2 hours, heating the ingot to forging temperature, which is (1150-1180)±10°To produce with arbitrary speed, and exposure at this temperature is carried out for 3-5 hours

2. The method according to claim 1, characterized in that prior to the recent removal of the forging of the head and bottom parts of the ingot otkalyvayut axle, Raskov cut in half and produce the final forging each half separately with the subsequent removal of the pins.

3. The method according to claim 1, characterized in that the forging of the ingot is carried out by precipitation, while before the draught from the head part of the ingot otkalyvayut the journal.

4. The method according to claim 1 or 2, characterized in that the forging of the ingot is carried out by scrubbing with a degree ukawa not less than 3 to cut the strikers on a circle-a circle with compression in one take-away is not more than 20 mm in the first passages.



 

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