Method for preparing gun steel based on rotary swaging and heat treatment

Abstract

The invention belongs to the field of alloy material manufacturing, and particularly relates to a method for preparing gun steel based on rotary swaging and heat treatment and a gun steel bar manufactured through the method. Comprising the following steps: (1) preparing a rod-shaped gun steel base material, and setting rotary swaging parameters including hammering frequency and die size; (2) the rod-shaped gun steel base material is subjected to multiple single-pass four-die rotary swaging at the room temperature, rotary swaging is conducted for 50-70 passes, and the single-pass four-die rotary swaging comprises the step that the rod-shaped gun steel base material is conveyed into a four-die rotary swaging machine through a feeding device to be subjected to four-die rotary swaging; (3) a gun steel bar with the diameter of 6.8 cm is finally obtained, and the total strain epsilon of the forged material is equal to 3; and (4) the bar obtained after rotary forging is subjected to annealing heat treatment in a muffle furnace, and finally the gun steel bar obtained after heat treatment is obtained. According to the invention, excellent comprehensive mechanical properties can be obtained through simple heat treatment without additional regulation and control, and tedious subsequent treatment is omitted; and the use requirements of places with higher mechanical property requirements are met.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of alloy material manufacturing, and particularly relates to a method for preparing gun steel based on rotary swaging and heat treatment, and gun steel bars prepared by the method. BACKGROUND

[0002] The Cr-Ni-Mo low-alloy ultra-high-strength steel has ultra-high yield strength and tensile strength, good toughness, weldability, plasticity and excellent corrosion resistance, and has great application potential in the military field and can be used as gun steel material. The continuous development of the gun towards high power and light weight determines that the gun steel material should have higher strength. Research shows that only the strength and toughness of the gun steel are properly matched, the use safety can be ensured. So far, most of the high-strength gun steel for medium and large caliber still belongs to the Cr, Ni, Mo and V system, so in order to obtain a new type of high-strength gun steel material, alloy elements should be reasonably used, and the new process should be focused on. Therefore, it is urgent to develop a new processing technology to develop high-strength and high-toughness gun steel material. SUMMARY

[0003] The purpose of the application is to provide a method for preparing gun steel based on rotary swaging and heat treatment, which processes the strengthening material through the rotary swaging process, and cooperates with the subsequent heat treatment to obtain gun steel material with excellent mechanical properties.

[0004] The technical solution for achieving the purpose of the application is as follows:

[0005] A method for preparing gun steel based on rotary swaging and heat treatment, comprising the following steps:

[0006] Step (1): preparing a rod-shaped gun steel base material, setting rotary swaging parameters, including beating frequency and die size;

[0007] Step (2): the rod-shaped gun steel base material is subjected to multiple single-pass four-die rotary swaging at room temperature, and the rotary swaging is performed for 50-70 passes, and the single-pass four-die rotary swaging comprises feeding the rod-shaped gun steel base material into the four-die rotary swaging machine for four-die rotary swaging by using a feeding device;

[0008] Step (3): finally obtaining a gun steel bar with a diameter of 6.8 cm, and the total strain of the material after swaging is obtained as ε=3;

[0009] Step (4): annealing heat treatment of the rod material after rotary swaging in a muffle furnace, and finally obtaining the gun steel bar after heat treatment.

[0010] Further, the rod-shaped gun steel base material in step (1) is composed of the following components with the mass fraction of C: 0.3%, Si: 0.28%, Mn: 0.45%, Cr: 0.94%, Ni: 3.08%, Mo: 0.46%, V: 0.1%, and the balance of Fe and unavoidable impurities.

[0011] Further, in step (1), the diameter of the bar-shaped gun steel base material is 30 mm, the forging head beating frequency is 30 times / s, and the initial forging die cavity aperture is 32 mm.

[0012] Further, in step (2), the single-pass four-die rotary forging pointer forging die performs short-stroke high-frequency radial motion.

[0013] Further, in step (2), the feeding end and the discharging end of the die cavity of the four-die rotary forging machine are formed into conical channels, and the conical angle of the conical channel at the feeding end is larger than that of the conical channel at the discharging end.

[0014] Further, in step (2), 50-70 passes of four-die rotary forging are performed at room temperature, and after each pass of rotary forging, a forging die with a smaller die cavity aperture and a precision-matched gasket are replaced for the next single-pass four-die rotary forging.

[0015] Further, in step (3), the rotary forging strain calculation formula is specifically: ε = 2ln(R0 / R), wherein R0 is the diameter of the initial bar material, and R is the diameter of the bar material after rotary deformation.

[0016] Further, in step (4), the temperature points of the muffle furnace are set to 650℃, 700℃, 750℃, 800℃, and 850℃, respectively, the rotary forged gun steel bars are placed in the furnace after the temperature in the furnace is uniform, and the bars are taken out after 30 minutes of heat preservation and cooled in air.

[0017] Compared with the prior art, the present application has the following advantages:

[0018] (1) The method for preparing gun steel based on rotary forging and heat treatment provided by the present application adopts a four-die rotary forging machine to produce small-diameter gun steel bars, and due to the effect of high-frequency loading four-way compressive stress, the stress distribution of the bars during rotary forging is more uniform, effectively preventing stress concentration caused by uneven compressive stress during two-die rotary forging, and avoiding defects such as peeling, cracking, and poor surface roughness of the bars during rotary forging; compared with ordinary mechanical processing, rotary forging can save materials by about 35%.

[0019] (2) The method for preparing gun steel based on rotary forging and heat treatment provided by the present application improves the mechanical properties of gun steel materials by improving the grain refinement efficiency, and improves the comprehensive mechanical properties by cooperating with the heat treatment process, so that the yield strength of the gun steel material is 1256-1349Mpa, the tensile strength is 1907-1911Mpa, and the elongation is 10.14-10.26%.

[0020] (3) The present invention provides a method for preparing gun steel based on rotary forging and heat treatment. The rod-shaped gun steel base material is composed of the following components in the following mass fractions: C: 0.3%, Si: 0.28%, Mn: 0.45%, Cr: 0.94%, Ni: 3.08%, Mo: 0.46%, V: 0.1%, with the balance being Fe and unavoidable impurities. The present invention can obtain excellent comprehensive mechanical properties through simple heat treatment without additional control, saving cumbersome subsequent processing; and meets the application requirements of places with higher mechanical performance requirements. Attached Figure Description

[0021] Figure 1 The diagram shows the yield strength and tensile strength of the gun steel bar obtained in Example 1 after being stretched twice.

[0022] Figure 2 The graph shows the elongation of the gun steel bar obtained in Example 1 after being stretched twice.

[0023] Figure 3 The graph shows the mechanical properties of the gun steel bar obtained in Example 1 after being repeatedly stretched twice.

[0024] Figure 4 The graph shows the changes in mechanical properties of the gun steel bars obtained in Example 1 after annealing at different temperatures. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] The present invention will now be described in further detail with reference to the accompanying drawings.

[0027] Example 1

[0028] A method for preparing gun steel based on rotary forging and heat treatment includes the following steps:

[0029] Step (1) Prepare a bar-shaped gun steel base material with a diameter of 30mm, turn on the rotary forging machine, set the rotary forging parameters, where the hammering frequency is 30 times / s, the initial size of the die is determined according to the initial diameter of the bar-shaped gun steel base material, and the initial forging die cavity diameter is 32mm.

[0030] Step (2) Use the feeding device to send the bar-shaped gun steel material to the four-die rotary forging machine for four-die rotary forging; the four forging dies of the four-die rotary forging machine are equipped with shims with matching precision, which can more effectively control the precision of the deformation between each pass, so that the error between the theoretical deformation and the actual deformation between each pass is smaller.

[0031] Step (3) During the first single-pass four-die rotary forging process, the single-pass four-die rotary forging refers to the forging die performing a short-stroke high-frequency radial motion; under the action of multi-directional forging and high-frequency loading, the diameter of the bar billet is reduced uniformly, and the deformation is completed. The feed end and discharge end of the die cavity of the four-die rotary forging machine both form conical channels. The cone angle of the conical channel at the feed end is greater than the cone angle of the conical channel at the discharge end; after rotary forging, the diameter of the raw material gun steel bar is reduced;

[0032] Step (4) After completing a single-pass four-die rotary forging, it is necessary to replace the die with a smaller cavity diameter before performing the next single-pass four-die rotary forging. Multi-pass four-die rotary forging uses four-way compressive stress and high-frequency pulse loading to make the internal grain structure of the rotary forging bar uniform and smaller.

[0033] Step (5) repeats steps (2), (3), and (4) multiple times. After 50-70 single-pass four-die rotary forging, a rotary forged gun steel bar with a diameter of 6.8 mm is obtained; the total strain obtained by the forged material is ε = 3.

[0034] Step (6) Open the muffle furnace and set five different temperature parameters: 650℃, 700℃, 750℃, 800℃, and 850℃. After the temperature inside the furnace is uniform, put the rotary forged gun steel bars into the furnace and keep them at that temperature for 30 minutes. Then take them out and cool them in the air to obtain the heat-treated gun steel material.

[0035] The rod-shaped gun steel base material is composed of the following components by mass fraction: C: 0.3%, Si: 0.28%, Mn: 0.45%, Cr: 0.94%, Ni: 3.08%, Mo: 0.46%, V: 0.1%, with the balance being Fe and unavoidable impurities;

[0036] Tensile tests were performed on the gun steel bars obtained in Example 1 to obtain data on tensile strength, yield strength, and elongation. The results are as follows: Figures 1-3 As shown in the figure, YS represents yield strength and UTS represents tensile strength.

[0037] Depend on Figure 1 , 2 It can be seen that the gun steel bar with the best comprehensive mechanical properties obtained by this invention has a yield strength of 1256–1349 MPa, a tensile strength of 1907–1911 MPa, and an elongation of 10.14–10.26%. Figure 1 , 2Based on, by Figure 3 It can be seen that the curves have a high degree of overlap, and the error of multiple tensile tests at this temperature is small.

[0038] Depend on Figure 4 It can be seen that the properties of gun steel materials obtained by annealing at different temperatures are different, and the gun steel materials obtained by annealing at 750℃ for 30 minutes have the best comprehensive mechanical properties.

[0039] The target parts obtained in the embodiments of the present invention can be used to manufacture corresponding products for use in fields such as machinery and military industries that have certain requirements for mechanical properties.

[0040] The equipment, operating steps, and operating methods not covered in this invention are the same as or can be implemented using existing technologies. They are not described in detail in this application.

[0041] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing gun steel based on swaging and heat treatment, characterized in that, It comprises the following steps: Step (1): preparing a bar-shaped cannon steel base material, setting the rotary forging parameters, including the frequency of hammering, the die size; Step (2): the bar-shaped cannon steel base material is subjected to multiple single-pass four-die rotary forging at room temperature, and the rotary forging is performed for 50-70 passes, wherein the single-pass four-die rotary forging comprises feeding the bar-shaped cannon steel base material into a four-die rotary forging machine for four-die rotary forging by using a feeding device; Step (3): finally obtaining a cannon steel bar with a diameter of 6.8 cm, and the total strain of the material after forging is ε=3; Step (4): annealing heat treatment of the bar after rotary forging in a muffle furnace, and finally obtaining the cannon steel bar after heat treatment.

2. The method of claim 1, wherein, In step (1), the bar-shaped cannon steel base material is composed of the following components with the mass fraction: C: 0.3%, Si: 0.28%, Mn: 0.45%, Cr: 0.94%, Ni: 3.08%, Mo: 0.46%, V: 0.1%, and the balance of Fe and inevitable impurities.

3. The method of claim 2, wherein, In step (1), the diameter of the bar-shaped cannon steel base material is 30 mm, and the frequency of hammering of the forging head is 30 times / s, and the initial forging die cavity hole diameter is 32 mm.

4. The method of claim 1, wherein, In step (2), the single-pass four-die rotary forging refers to the short-stroke high-frequency radial motion of the forging die; under the action of multi-directional forging and high-frequency loading, the bar-shaped blank is uniformly reduced in diameter and the deformation is completed.

5. The method of claim 4, wherein, In step (2), the feeding end and the discharging end of the die cavity of the four-die rotary forging machine form a conical channel, and the conical angle of the conical channel at the feeding end is greater than that at the discharging end.

6. The method of claim 5, wherein, In step (2), 50-70 passes of four-die rotary forging are performed at room temperature, and after each pass of rotary forging, a forging die with a smaller die cavity hole diameter and a precision-matched gasket are replaced for the next single-pass four-die rotary forging.

7. The method of claim 1, wherein, In step (3), the rotary forging strain calculation formula is specifically: ε=2ln(R0 / R), wherein R0 is the diameter of the bar-shaped cannon steel base material, and R is the diameter of the cannon steel bar after rotary deformation.

8. The method of claim 1, wherein, In step (4), the temperature points of the muffle furnace are set to 650℃, 700℃, 750℃, 800℃, and 850℃, respectively, and after the temperature in the furnace is uniform, the rotary forged cannon steel bars are placed in the furnace, and after 30 min of heat preservation, they are taken out and cooled in air.

9. A gun steel material characterized by, Prepared by the method of any one of claims 1-8.

Images