CN103639220A - Extrusion forming method of nickel alloy tube blank - Google Patents

Abstract

The invention provides a nickel alloy billet extrusion molding method, the method is: heating the nickel alloy billet to a certain temperature, and then selecting a suitable extrusion die, extrusion ratio and extrusion rate for the nickel alloy billet Extruding is carried out, and finally the extruded nickel alloy billet is water-quenched to obtain a nickel alloy billet. In the present invention, by selecting a suitable extrusion die and optimizing and improving process parameters such as ingot heating temperature, extrusion speed, extrusion ratio, etc., various defects produced by the traditional extrusion process can be significantly improved, and finally the surface quality is good, High-quality tube blanks with high dimensional accuracy and good structural properties.

Description

A kind of extrusion molding method of nickel alloy tube billet

technical field

The invention belongs to the technical field of nickel alloy material processing, and in particular relates to an extrusion molding method of a nickel alloy tube billet.

Background technique

Nickel-based superalloys have the advantages of anti-oxidation, corrosion resistance, and high service temperature. Superalloys are also widely used in aerospace, nuclear engineering, energy power, transportation, petrochemical and metallurgy and other fields.

The unique alloy composition and microstructure of nickel-based superalloys determine that its extrusion forming process is different from other common materials. Compared with other types of materials, nickel-based superalloys have the following forming characteristics:

(1) The material has high strength and poor fluidity, so the forming of nickel-based superalloy tube billet is difficult and the scrap rate is high;

(2) High deformation resistance. Due to the complex composition of the superalloy and the high recrystallization temperature, it has high deformation resistance and hardening tendency at the deformation temperature, and the deformation resistance is 4-7 times that of ordinary structural steel;

(3) The extrusion deformation temperature range is narrow. Compared with steel, high-temperature alloy has a lower melting point, and excessive heating temperature can easily cause overburning and overheating. If the temperature is too low, the plasticity is low, the deformation resistance is large, and it is easy to produce cold and hot mixed deformation, resulting in uneven coarse grains.

Therefore, it is an urgent problem to be solved to select a reasonable hot extrusion process parameter and process method to obtain a nickel-based superalloy hot extrusion tube billet with high surface quality and good microstructure.

Contents of the invention

The technical problem to be solved by the present invention is to provide an extrusion molding method of a nickel alloy tube billet for the deficiencies of the above-mentioned prior art. By selecting a suitable extrusion die and optimizing and improving process parameters such as ingot heating temperature, extrusion speed, and extrusion ratio, this method can significantly improve various defects caused by traditional extrusion processes, and finally obtain good surface quality, High-quality tube blanks with high dimensional accuracy and good structural properties.

In order to solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a nickel alloy billet extrusion molding method, which is characterized in that the method is: heating the nickel alloy billet whose cross-sectional shape is circular to 1150 ℃～1230℃, and then extrude the heated nickel alloy ingot by extruder under the condition of extrusion ratio of 3.5～5.0 and extrusion speed of 40mm/s, and then extrude the extruded nickel alloy ingot The billet is cooled by water quenching to obtain a nickel alloy tube billet; the extrusion die in the extruder is a conical die, and the die angle of the conical die is α=60°.

The above-mentioned extrusion molding method of a nickel alloy tube billet is characterized in that the nickel alloy is GH690 nickel alloy or GH625 nickel alloy.

The above-mentioned extrusion molding method of a nickel alloy billet is characterized in that, before extruding the heated nickel alloy billet, a lubricant needs to be uniformly applied to the inner and outer surfaces of the nickel alloy billet in advance.

The above-mentioned extrusion molding method of a nickel alloy billet is characterized in that, before the heated nickel alloy billet is extruded, the extrusion barrel, extrusion needle and extrusion The molds are heated to 350°C to 380°C for preheating.

Compared with the prior art, the present invention has the following advantages:

1. The present invention mainly includes the selection of the concave model surface and the optimization of the die angle by carrying out a large number of optimized designs to the extrusion die; According to the influence law of pressure, the conical concave die with die angle α=60° is finally determined as the extrusion die.

2. The invention has the advantages of low cost, high production efficiency, high material utilization rate, and good microstructure of tube blanks, etc., and can meet the needs of mass production of nickel-based superalloy tube blanks by hot extrusion.

3. The present invention can significantly improve various defects produced by the traditional extrusion process by selecting a suitable extrusion die and optimizing and improving process parameters such as ingot heating temperature, extrusion speed, and extrusion ratio, and finally obtains surface quality Good, high dimensional accuracy, high-quality tube blanks with good organizational properties.

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a structural schematic diagram of an extrusion die of the present invention.

Fig. 2(a) is a photo of the metallographic structure of the outer surface of the nickel alloy tube blank in Example 1 of the present invention.

Fig. 2(b) is a photograph of the metallographic structure of the inner surface of the nickel alloy tube blank in Example 1 of the present invention.

Fig. 3(a) is a photo of the metallographic structure of the outer surface of the nickel alloy tube blank in Example 2 of the present invention.

Fig. 3(b) is a photo of the metallographic structure of the inner surface of the nickel alloy tube blank in Example 2 of the present invention.

Fig. 4(a) is a photo of the metallographic structure of the outer surface of the nickel alloy tube blank in Example 3 of the present invention.

Fig. 4(b) is a photograph of the metallographic structure of the inner surface of the nickel alloy tube blank in Example 3 of the present invention.

Fig. 5(a) is a photo of the metallographic structure of the outer surface of the nickel alloy tube blank in Example 4 of the present invention.

Fig. 5(b) is a photo of the metallographic structure of the inner surface of the nickel alloy tube blank in Example 4 of the present invention.

Fig. 6 is the variation curve of the flow rate of the nickel alloy of the present invention as a function of the mold angle.

Fig. 7 is the variation curve of extrusion force with die angle in the present invention.

Explanation of reference signs:

α—module angle.

Detailed ways

Example 1

Extrusion method of GH690 nickel alloy tube billet:

Step 1. Nickel alloy ingot heating and lubrication: heat the GH690 nickel alloy ingot with outer diameter D=116.3mm, inner diameter D=44.8mm, and height L=184mm to 1200°C, and then uniformly coat the inner and outer surfaces of the nickel alloy ingot Coated with glass powder lubricant;

Step 2, mold preheating and lubrication: preheat the extrusion cylinder, extrusion die and extrusion needle in the extruder to 350°C; in the specific implementation process, the extrusion cylinder, extrusion die and extrusion Heat the indenter to 150°C, spray lubricant, and then heat to 350°C; the extrusion die is a conical die, and its die angle α=60°;

Step 3, hot extrusion forming: first install the heated glass mat on the extrusion die, then install the nickel alloy ingot, graphite mat, and extrusion mat in the extrusion cylinder in turn, and then start extrusion, the extrusion speed is 40mm/s, extrusion ratio is 3.5;

Step 4, water quenching: put the tube blank after hot extrusion into cold water for water quenching, retain the structure after high temperature deformation, and prevent the grain from growing.

Step 5. Cleaning: Clean the inner and outer surfaces of the hot-extruded tube billet, and perform a small amount of machining to remove the incomplete recrystallization part close to the mold due to temperature drop, so as to obtain a tube billet with high surface quality and good structure performance. Prepare for the subsequent cold rolling process.

The photo of the metallographic structure of the outer surface of the nickel alloy tube blank in this embodiment is shown in Figure 2(a), and the photo of the metallographic structure of the inner surface of the tube blank is shown in Figure 2(b). It can be seen from Fig. 2(a) and Fig. 2(b) that due to the adoption of a reasonable hot extrusion process in this embodiment, the formability of the material is significantly improved and a high-quality tube blank is obtained. After the tube blank is hot-extruded, the inner and outer surfaces of the tube wall are fine equiaxed crystals.

Example 2

Extrusion method of GH690 nickel alloy tube billet:

Step 1. Heating and lubricating the nickel alloy ingot: heat the GH690 nickel alloy ingot with outer diameter D=116.2mm, inner diameter D=45mm, and height L=153mm to 1230°C, and then evenly coat the inner and outer surfaces of the nickel alloy ingot with Glass powder lubricant;

Step 2, mold preheating and lubrication: preheat the extrusion cylinder, extrusion die and extrusion needle in the extruder to 350°C; in the specific implementation process, the extrusion cylinder, extrusion die and extrusion Heat the indenter to 100°C, spray lubricant, and then heat to 350°C; the extrusion die is a conical die, and its die angle α=60°;

Step 3, hot extrusion forming: first install the heated glass mat on the extrusion die, then install the nickel alloy ingot, graphite mat, and extrusion mat in the extrusion cylinder in turn, and then start extrusion, the extrusion speed is 40mm/s, extrusion ratio is 4.1;

Step 4, water quenching: put the tube blank after hot extrusion into cold water for water quenching, retain the structure after high temperature deformation, and prevent the grain from growing.

Step 5. Cleaning: Clean the inner and outer surfaces of the hot-extruded tube billet, and perform a small amount of machining to remove the incomplete recrystallization part close to the mold due to temperature drop, so as to obtain a tube billet with high surface quality and good structural properties. Prepare for the subsequent cold rolling process.

The photo of the metallographic structure of the outer surface of the nickel alloy tube blank in this embodiment is shown in Figure 3(a), and the photo of the metallographic structure of the inner surface of the tube blank is shown in Figure 3(b). It can be seen from Fig. 3(a) and Fig. 3(b) that due to the adoption of a reasonable hot extrusion process in this embodiment, the formability of the material is significantly improved and a high-quality tube blank is obtained. After the tube blank is hot-extruded, the inner and outer surfaces of the tube wall are fine equiaxed crystals.

Example 3

Extrusion method of GH625 nickel alloy tube billet:

Step 1. Nickel alloy ingot heating and lubrication: heat the GH625 nickel alloy ingot with outer diameter D = 116.3mm, inner diameter D = 44.8mm, and height L = 142.2mm to 1150°C, and then heat the inner and outer surfaces of the nickel alloy ingot Uniform coating of glass powder lubricant;

Step 2. Die preheating and lubrication: Preheat the extrusion barrel, extrusion die and extrusion needle in the extruder to 360°C; in the specific implementation process, the extrusion barrel, extrusion die and extrusion After heating the indenter to 150°C, spray lubricant, and then heat to 360°C; the extrusion die is a conical die, and its die angle α=60°;

Step 3, hot extrusion forming: first install the heated glass pad on the top of the extrusion die, then install the nickel alloy ingot, graphite pad, and extrusion pad in the extrusion cylinder in turn, and then start extrusion, extrusion The speed is 40mm/s, and the extrusion ratio is 5.0;

Step 4, water quenching: put the tube blank after hot extrusion into cold water for water quenching, retain the structure after high temperature deformation, and prevent the grain from growing.

Step 5. Cleaning: Clean the inner and outer surfaces of the hot-extruded tube billet, and perform a small amount of machining to remove the incomplete recrystallization part close to the mold due to temperature drop, so as to obtain a tube billet with high surface quality and good structure performance. Prepare for the subsequent cold rolling process.

The photo of the metallographic structure of the outer surface of the nickel alloy tube blank in this embodiment is shown in Figure 4(a), and the photo of the metallographic structure of the inner surface of the tube blank is shown in Figure 4(b). It can be seen from Fig. 4(a) and Fig. 4(b) that due to the adoption of a reasonable hot extrusion process in this embodiment, the formability of the material is significantly improved, and a high-quality tube blank is obtained. After the tube blank is hot-extruded, the inner and outer surfaces of the tube wall are fine equiaxed crystals.

Example 4

Extrusion method of GH625 nickel alloy tube billet:

Step 1. Heating and lubricating the nickel alloy ingot: Heat the GH625 nickel alloy ingot with outer diameter D=116.5mm, inner diameter D=45mm, and height L=148mm to 1200°C, and then evenly coat the inner and outer surfaces of the nickel alloy ingot with Glass powder lubricant;

Step 2, mold preheating and lubrication: preheat the extrusion cylinder, extrusion die and extrusion needle in the extrusion machine to 380 °C; in the specific implementation process, the extrusion cylinder, extrusion die and extrusion needle can be first After heating the indenter to 135°C, spray lubricant, and then heat to 380°C; the extrusion die is a conical die with a die angle of 60°;

Step 3, hot extrusion forming: first install the heated glass pad on the top of the extrusion die, then install the nickel alloy ingot, graphite pad, and extrusion pad in the extrusion cylinder in turn, and then start extrusion, extrusion The speed is 40mm/s, and the extrusion ratio is 5.0;

Step 4, water quenching: put the tube blank after hot extrusion into cold water for water quenching, retain the structure after high temperature deformation, and prevent the grain from growing.

Step 5. Cleaning: Clean the inner and outer surfaces of the hot-extruded tube billet, and perform a small amount of machining to remove the incomplete recrystallization part close to the mold due to temperature drop, so as to obtain a tube billet with high surface quality and good structure performance. Prepare for the subsequent cold rolling process.

The photo of the metallographic structure of the outer surface of the nickel alloy tube blank in this embodiment is shown in Figure 5(a), and the photo of the metallographic structure of the inner surface of the tube blank is shown in Figure 5(b). It can be seen from Fig. 5(a) and Fig. 5(b) that due to the adoption of a reasonable hot extrusion process in this embodiment, the formability of the material is significantly improved, and a high-quality tube blank is obtained. After the tube blank is hot-extruded, the inner and outer surfaces of the tube wall are fine equiaxed crystals.

The present invention uses a conical concave die with a die angle of α=60° as the extrusion die, the extrusion rate is 40mm/s, and the billet heating temperature is 1150°C to 1230°C, which is obtained after a large number of creative tests. The specific analysis is as follows:

1) Selection of extrusion die:

The design of the extrusion die in the present invention mainly includes the selection of the concave die surface and the optimization of the die angle. Among them, the concave model surface mainly includes a sinusoidal die (concave oval die), a cosine curve die (convex oval die), a hyperbola die (hyperbola die) and a conical die (conical die). By comprehensively considering the influence of different concave model surfaces and die angles on velocity field, equivalent strain and extrusion force, the conical concave die with die angle α=60° was finally determined as the extrusion die.

The present invention selects the sinusoidal concave die, the cosine curved concave die, the hyperbolic concave die and the tapered concave die to be the extrusion die respectively, and when measuring and adopting different concave dies to carry out extrusion molding, the flow rate of the nickel alloy is different from that of the die. The relationship curve of angle is shown in Fig. 6. It can be seen from Figure 6 that no matter it is a sinusoidal concave die, a cosine curved concave die, a hyperbolic concave die, or a conical concave die, when the die angle α satisfies: 60°≤α≤70°, it is most beneficial to nickel alloy flow.

The present invention selects the sinusoidal concave die, the cosine curved concave die, the hyperbolic concave die and the conical concave die to be the extrusion dies respectively, and when measuring and adopting the concave dies with different die angles to carry out extrusion molding, the extrusion force and The relationship curve of the mold angle is shown in Figure 7. It can be seen from Figure 7 that when the extrusion die is a conical die and the die angle α=60°, the extrusion force is the smallest and the requirements for equipment are the lowest. Therefore, the present invention finally selects the die angle α after many creative tests. = 60 ° conical die for the extrusion die.

2) Selection of nickel alloy ingot heating temperature:

In the extrusion molding process, the heating temperature of the nickel alloy billet is very important. If the heating temperature is too high, overheating or overburning will occur, which will make the grain structure of the extruded tube blank coarse and reduce the performance of the tube blank. If the heating temperature is too low, the extrusion force will be significantly increased, and problems such as stuffy cars may even occur. Since the extrusion temperature range of nickel-based superalloys such as GH625 and GH690 is relatively narrow, it is necessary to determine a reasonable extrusion temperature range to ensure the smooth progress of the extrusion process. Therefore, the present invention finally selects the heating temperature of the nickel alloy ingot to be 1150° C. to 1230° C. after several inventive tests.

3) Selection of extrusion rate:

Extrusion rate is another important factor affecting the extrusion process. Generally speaking, the higher the extrusion rate, the greater the extrusion force. The softening of the nickel alloy billet will reduce the extrusion force, so the actual extrusion force increases with the extrusion rate in a process of first increasing, then decreasing, and then increasing; when the extrusion rate is low, the extrusion needle and nickel The heat transfer time between the alloy ingots is relatively long, and the extrusion needle will be deformed by heat. Therefore, after many creative tests, the extrusion rate of the present invention is finally selected to be 40mm/s, which will not be deformed due to exposure, and the extrusion force Not too big.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent changes made to the above embodiments according to the technical essence of the invention still belong to the protection scope of the technical solution of the invention.

Claims (4)

1. the extrusion process of a nickel alloy pipe, it is characterized in that, the method is: the nickel alloy ingot blank that is annular by shape of cross section is heated to 1150 ℃～1230 ℃, recycling extruder is 3.5～5.0 by the nickel alloy ingot blank after heating in extrusion ratio, extruding rate is to push under the condition of 40mm/s, then the nickel alloy ingot blank after extruding is carried out to shrend cooling, obtain nickel alloy pipe; Extrusion die in described extruder is taper matrix, modular angle α=60 ° of described taper matrix.

2. the extrusion process of a kind of nickel alloy pipe according to claim 1, is characterized in that, described nickel alloy is GH690 nickel alloy or GH625 nickel alloy.

3. the extrusion process of a kind of nickel alloy pipe according to claim 1, is characterized in that, before the nickel alloy ingot blank to after heating pushes, needs at the surfaces externally and internally of nickel alloy ingot blank, evenly to smear lubricant in advance.

4. the extrusion process of a kind of nickel alloy pipe according to claim 1, it is characterized in that, before the nickel alloy ingot blank to after heating pushes, need the recipient in extruder, squeezing needle and extrusion die be all heated to 350 ℃～380 ℃ in advance and carry out the pre-heat treatment.

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