A method for improving the strength of an in625 alloy ring forging

Abstract

The application discloses a method for improving the strength of IN625 alloy ring forgings, which comprises the steps of upsetting, punching, horse frame hole expanding, pre-rolling, final rolling and low-temperature bulging. The application refines the grains by adopting high-temperature blanking (including the upsetting and punching and horse frame hole expanding processes) and large deformation forging, and keeps the grains from growing by adopting low-temperature rolling and small deformation forging. The work hardening effect is improved through low-temperature bulging after rolling. The above method can improve the strength of IN625 material forgings, and the IN625 alloy ring forgings with good grain size and mechanical properties are obtained.

Description

TECHNICAL FIELD

[0001] The application relates to a method for improving the strength of an IN625 alloy ring-shaped forge piece and belongs to the field of high-temperature alloy ring-shaped forge piece forging. BACKGROUND

[0002] The IN625 alloy is a nickel-based corrosion-resistant high-temperature alloy, has excellent inorganic acid corrosion resistance, and has very excellent corrosion resistance to various corrosive media in oxidation and reduction environments. The IN625 alloy is required to have good strength when used below 650 DEG C.

[0003] The existing forming method of the IN625 alloy ring-shaped forge piece is generally as follows: upsetting, punching, mandrel expanding at 1060-1080 DEG C, deformation of 40%-50%; pre-rolling at 1000-1020 DEG C, deformation of 25-30%; and final rolling forming at 1000-1020 DEG C, deformation of 25-30%. The IN625 alloy ring-shaped forge piece processed by the forming method is prone to not meeting the specification requirements in tensile strength. SUMMARY

[0004] The application aims to solve the technical problem of providing a method for improving the strength of an IN625 alloy ring-shaped forge piece to solve the problems in the prior art.

[0005] The technical scheme adopted by the application is as follows: a method for improving the strength of an IN625 alloy ring-shaped forge piece, which comprises the steps of upsetting, punching, mandrel expanding, pre-rolling, final rolling and low-temperature bulging, and the heating temperature of the upsetting, punching and mandrel expanding steps is controlled to be 1060-1080 DEG C.

[0006] Preferably, the upsetting, punching and mandrel expanding steps are operated as follows: the blank is first upset on a quick forging machine, then the upset raw material is punched by a punch to make the center thereof be punched through to form a ring piece, then the ring piece is placed on a mandrel, and the outer circular surface of the ring piece is pressed by a hammer to expand the mandrel, so that the inner and outer diameters of the blank are increased and the wall thickness is reduced. The above process is completed in one heating, and the deformation is 55%-65%.

[0007] Preferably, the pre-rolling step is operated as follows: the heating temperature is controlled to be 950-1000 DEG C, the ring piece after the mandrel expanding is pre-rolled by a numerical control radial-axial ring rolling machine, and the pre-rolling is completed in one heating, and the deformation is 18%-25%.

[0008] Preferably, the final rolling step is operated as follows: the heating temperature is controlled to be 930-980 DEG C, the ring piece after the pre-rolling is finally rolled by a numerical control radial-axial ring rolling machine, and the final rolling is completed in one heating, and the deformation is 7%-12%.

[0009] Preferably, the ring is placed on the expander immediately after finish rolling to perform the expansion, with a deformation of 2% to 5%; the temperature range for the low-temperature expansion is 800-930℃.

[0010] The beneficial effects of the present application are as follows: compared with the prior art, the present application adopts high temperature (temperature of 1060-1080℃) and large deformation (deformation of more than 50%) to refine the grains during the blanking (upsetting, punching and mandrel expanding processes); low temperature (temperature of 950-1000℃) and small deformation (deformation of 18%-25%) are adopted during the intermediate rolling stage; low temperature (temperature of 930-980℃) and small deformation (deformation of 7%-12%) are adopted during the finish rolling process to prevent the grains from growing; and low-temperature expansion (performed immediately after finish rolling without heating, at a temperature of 800-930℃) is adopted to improve the work hardening effect, so as to achieve the purpose of improving the strength of the IN625 material forging, and obtain the IN625 alloy ring forging with good grain size and mechanical properties. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 The high-power microscope structure diagram of the forging of Comparative Example 1;

[0012] Figure 2 The high-power microscope structure diagram of the forging of Example 1;

[0013] Figure 3 The high-power microscope structure diagram of the forging of Example 2;

[0014] Figure 4 The high-power microscope structure diagram of the forging of Example 3. DETAILED DESCRIPTION

[0015] The present application will be further described below in combination with the drawings and specific examples.

[0016] Example 1:

[0017] A method for improving the strength of an IN625 alloy ring forging, comprising the steps of upsetting, punching, mandrel expanding, pre-rolling, finish rolling and low-temperature expansion.

[0018] The material of the forging product is IN625 high-temperature alloy, the size of the ring forging product is Φ343×Φ247×50, and the weight is 18.6kg, which is a small ring forging.

[0019] Blanking: IN625 alloy bars are used as raw materials for blanking, and the blanking size is Φ150×139mm.

[0020] The upsetting, punching and horse frame expanding three steps are controlled at a heating temperature of 1080°C, the blank is upset to a height H=60±5mm on a fast forging machine, a Φ100mm punch is used to punch the upset blank, and then the ring piece is placed on a horse frame to expand to a size of ~Φ274xΦ140±10x50±10mm. The above process is completed in one fire, and the deformation of the upsetting, punching and horse frame expanding three steps is ensured to be 55% by controlling the size.

[0021] The pre-rolling step is controlled at a heating temperature of 980°C, and the horse frame expanded blank is pre-rolled to a size of ~Φ317xΦ210±10x50±5mm by using a numerical control radial-axial ring rolling machine. The pre-rolling step is completed in one fire, and the deformation is 20%.

[0022] The finish rolling step is used to finish rolling the pre-rolled blank to a size of ~Φ343xΦ247±10x50±5mm by using a numerical control radial-axial ring rolling machine, the heating temperature is controlled at 930°C, the finish rolling step is completed in one fire, and the deformation of the finish rolling step is 11%.

[0023] The low-temperature bulging step is performed immediately after the finish rolling step without heating, the temperature is 880°C, the ring piece is bulged to a final size of Φ346xΦ252±10x50±5mm by using a bulging machine, and the deformation of the low-temperature bulging step is 2%.

[0024] Example 2:

[0025] A method for improving the strength of an IN625 alloy ring forging, comprising the steps of upsetting, punching, horse frame expanding, pre-rolling, finish rolling and low-temperature bulging.

[0026] The material of the forging product is IN625 high-temperature alloy, the ring forging has a size of Φ343xΦ247x50, and a weight of 18.6kg, which is a small ring forging.

[0027] Blanking, using IN625 alloy bar as raw material for blanking, the blanking size is Φ150x139mm.

[0028] The heating temperature of the upsetting, punching and horse frame expanding three steps is controlled at 1070°C, the blank is upset to a height H=60±5mm on a fast forging machine, a Φ100mm punch is used to punch the upset blank, and then the ring piece is placed on a horse frame to expand to a size of ~Φ274xΦ140±10x50±10mm. The above process is completed in one fire, and the deformation of the upsetting, punching and horse frame expanding three steps is ensured to be 55% by controlling the size.

[0029] Pre-rolling step, heating temperature control at 990℃, using numerical control diameter shaft ring rolling machine to expand hole after the blank pre-rolling to the size of ~ Φ317xΦ210±10x50±5mm. 1 fire is completed, the deformation of pre-rolling step is 20%.

[0030] Final rolling step, using numerical control diameter shaft ring rolling machine to pre-rolling after the blank final rolling to the size of ~ Φ343xΦ247±10x50±5mm, heating temperature control at 950℃, 1 fire is completed, the deformation of final rolling step is 11%.

[0031] Low temperature bulging step, immediately after the final rolling, without heating, the temperature is 900℃, using bulging machine to expand the ring to the final size of Φ346xΦ252±10x50±5mm, the deformation of low temperature bulging step is 2%.

[0032] Example 3:

[0033] A method for improving the strength of IN625 alloy ring forgings, comprising upsetting, punching, hole expanding, pre-rolling, final rolling and low temperature bulging steps.

[0034] The material of the forging product is IN625 high temperature alloy, ring forgings, the size is Φ343xΦ247x50, the weight is 18.6kg, which is a small ring forging.

[0035] Blanking, using IN625 alloy bar as raw material for blanking, the blanking size is Φ150x139mm.

[0036] The heating temperature of the three steps of upsetting, punching and hole expanding is controlled at 1080℃, the blank is upset to a height H=60±5mm on the fast forging machine, the punched blank is punched by a Φ100mm punch, and then the ring is placed on the horse to expand the hole to the size of ~ Φ274xΦ145±10x50±10mm. The above process is completed in 1 fire, and the deformation of the three steps of upsetting, punching and hole expanding is ensured to be 60% by controlling the size.

[0037] Pre-rolling step, heating temperature control at 980℃, using numerical control diameter shaft ring rolling machine to expand hole after the blank pre-rolling to the size of ~ Φ317xΦ220±10x50±5mm. 1 fire is completed, the deformation of pre-rolling step is 22%.

[0038] Final rolling step, using numerical control diameter shaft ring rolling machine to pre-rolling after the blank final rolling to the size of ~ Φ343xΦ247±10x50±5mm, heating temperature control at 930℃, 1 fire is completed, the deformation of final rolling step is 7.8%.

[0039] Low temperature expansion step, immediately after finish rolling, without heating, temperature is 880℃, using expander to expand the ring to the final size of Φ346×Φ252±10×50±5mm, the deformation of low temperature expansion step is 2%.

[0040] Comparative Example 1

[0041] A method for improving the strength of IN625 alloy ring-shaped forgings, comprising the steps of upsetting, piercing, mandrel expanding, pre-rolling, finish rolling and low temperature expansion.

[0042] The material of the forging product is IN625 high-temperature alloy, the ring-shaped forging has a size of Φ343×Φ247×50 and a weight of 18.6kg, and is a small ring-shaped forging.

[0043] Blanking, using IN625 alloy bar as raw material for blanking, the blanking size is Φ150×139mm.

[0044] The heating temperature of the three steps of upsetting, piercing and mandrel expanding is controlled at 1080℃, the blank is upset to a height H=60±5mm on a fast forging machine, the upset blank is pierced using a Φ100mm punch, and then the ring is placed on the mandrel for mandrel expanding to a size of ~Φ274×Φ140±10×50±10mm. The above process is completed in one fire, and the deformation of the three steps of upsetting, piercing and mandrel expanding is ensured to be 55% by controlling the size.

[0045] Finish rolling step, using a numerical control radial-axial ring rolling machine to finish rolling the pre-rolled blank to a size of ~Φ346×Φ252±10×50±5mm, the heating temperature is controlled at 1000℃, and the finish rolling step is completed in one fire, and the deformation of the finish rolling step is 29%.

[0046] The results of the physical and chemical performance test of the forging product are as follows:

[0047] Table 1 Mechanical property test results of Comparative Example 1

[0048]

[0049] Table 2 Mechanical property test results of Example 1-3

[0050]

[0051]

[0052] The high-power microscope microstructure of the forgings of Comparative Example 1 and Examples 1-3 is as follows: Figures 1-4As shown: the grain size of the comparative example 1 is 4-6.5 grade, the structure is uneven; the grain size of the example 1 is 7-7.5 grade, the distribution is uniform; the grain size of the example 2 is 7-8 grade, the distribution is uniform; the grain size of the example 3 is 7-7.5 grade, the distribution is uniform.

[0053] The results of the comparative example 1 and the examples 1-3 show that: in the comparative example 1, after the hole of the maraging steel is reamed, the direct medium-temperature large-deformation rolling forming is carried out, there is no low-temperature small-deformation pre-rolling and low-temperature bulging process, after the prepared product is heat treated, the grain size meets the requirements, but there is mixed crystal in the local part, and the mechanical property is low; in the examples 1-3, the high temperature and the larger deformation are adopted to refine the grain, in the intermediate rolling stage, the lower temperature and the smaller deformation are adopted, in the final rolling process, the low-temperature and small-deformation forging is adopted to keep the grain from growing; after the rolling, the low-temperature bulging (carried out immediately after the final rolling, without heating) is adopted to improve the work hardening effect, through the present application, the purpose of improving the strength of the IN625 material forging is achieved, and the better grain size and the mechanical property are obtained.

[0054] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application, therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method of increasing the strength of an IN625 alloy ring forging, characterized by: The upsetting, punching, horse frame expanding, pre-rolling, final rolling and low temperature bulging steps are included, the heating temperature of the upsetting, punching and horse frame expanding steps is controlled at 1060-1080℃; The upsetting, punching, horse frame expanding steps are operated as follows: the blank is first upset on a fast forging machine, then the punched blank is punched by a punch to make the center thereof be punched through to form a ring, then the ring is placed on a horse frame, and the outer surface of the ring is pressed by a hammer to expand the ring to make the inner and outer diameters of the blank increase and the wall thickness decrease, the above process is completed in one heating, and the deformation is 55%-65%; The pre-rolling step is operated as follows: the heating temperature is controlled at 950-1000℃, the ring after the horse frame expanding is pre-rolled by a numerical control radial-axial ring rolling machine, the process is completed in one heating, and the deformation is 18%-25%; The final rolling step is operated as follows: the heating temperature is controlled at 930-980℃, the ring after the pre-rolling is finally rolled by a numerical control radial-axial ring rolling machine, the process is completed in one heating, and the deformation is 7%-12%; After the final rolling of the ring, the ring is immediately placed on a bulging machine to be bulged without heating, and the deformation is 2%-5%; the temperature range of the low temperature bulging is 800-930℃.

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