CN110042221A - A kind of method that pulse current eliminates A508-3 steel aging embrittlement - Google Patents

Abstract

The invention provides a method for eliminating aging and embrittlement of A508-3 steel by pulse current. The invention fixes the aging A508-3 steel on a pulse power supply, and continuously applies current pulses until a corresponding time. Pulse current treatment is carried out, and the pulse current action parameters and pulse current action time are determined according to the ageing and embrittlement degree of the evaluated A508‑3 steel and the size of the sample; the parameter range of pulse current treatment: frequency 1~2000Hz, pulse width 20μs~ 1ms, current 10~5000A, action time 5min~10h. The invention can process the radiation embrittlement A508-3 steel "in situ", so that the number of dislocation defects of the aged and embrittled A508-3 steel can be greatly reduced, and then its Charpy impact toughness can be recovered. At the same time, it can further reduce the temperature required to eliminate the embrittlement of A508‑3 steel, saving a lot of energy.

Description

A method for eliminating aging embrittlement of A508-3 steel by pulse current

technical field

The invention belongs to the field of metal material processing, in particular to a method for eliminating aging embrittlement of A508-3 steel by pulse current, and further relates to a method for eliminating defects in aging embrittlement A508-3 steel by pulse current to improve toughness.

Background technique

Nuclear energy is called green energy. In today's harsh global environment and tight energy supply, all countries in the world take nuclear energy as a development direction. At present, the number of nuclear power plants under construction and the total planned installed capacity in my country both rank first in the world. Most of the nuclear power plants that have been built and planned are pressurized water reactor nuclear power plants. The core structural component of the third-generation pressurized water reactor nuclear power plant - the reactor pressure vessel is made of A508-3 steel. A508-3 steel has better toughness and corrosion resistance than the second generation reactor pressure vessel material. During the service process of the reactor pressure vessel, the A508-3 steel will be irradiated by high-energy neutron beams and cause radiation embrittlement damage. The high-energy neutrons impact the material will produce Frankel defects, causing the precipitation of precipitation phases, promoting dislocation proliferation and hindering The dislocations move, resulting in dislocation loop defects. The macroscopic mechanical properties show that the hardness and strength of the material increase, the toughness decreases seriously, the ductile-brittle transition temperature increases, and the material is prone to low stress fracture. At the same time, the service temperature of the pressure vessel is 280 ℃ ~ 330 ℃, and the A508-3 steel will also produce thermal aging damage during the service process, which will accelerate the material failure. The radiation embrittlement damage of A508-3 steel seriously threatens the safe operation of nuclear power plants on the one hand, and greatly reduces the service life of nuclear power plants on the other hand.

At present, the repair method for the A508-3 steel damaged by irradiation embrittlement is to anneal it. -3 steel is annealed at 460°C for up to 168h with this method. Long-term annealing treatment can reduce or eliminate the internal stress of A508-3 steel, thereby reducing or eliminating dislocation defects, and repairing the radiation embrittlement damage of the pressure vessel. This traditional annealing treatment method is only suitable for damaged materials with small size. The steel used for pressure vessels in service is huge and cannot be disassembled for life. The annealing treatment method cannot repair the damage. In addition, the annealing treatment The time-consuming is relatively long compared to the time for the nuclear power plant to be shut down for maintenance. Therefore, the method of annealing treatment to repair the radiation embrittlement damage of A508-3 steel for nuclear pressure vessels is not feasible for on-site implementation.

Pulse current is a special treatment method of instantaneous high energy, which can improve the properties of metal materials. The patent (CN102260785A) discloses a device for eliminating residual stress by applying pulse current. The invention designs a power input module including a power supply, a capacitor energy storage bank for storing electric energy, a charging module for charging the capacitor energy storage bank, and a charging module for charging the capacitor energy storage bank. The electric energy stored in the capacitor energy storage group is released to the discharge module of the load and other devices, and the high-energy pulse current can be applied to the workpiece to eliminate the residual stress inside the workpiece. However, the invention does not mention the effect of pulse current on dislocation, and the device consumes a lot of energy and occupies a large area, so it is not suitable for practical application. The patent (CN108315549A) discloses a method for regenerating the performance of aged duplex stainless steel under the action of pulse current. The present patent uses pulse current to eliminate dislocation defects in aging and embrittled A508-3 steel. The research object and research content of the two are very different.

This patent utilizes the electron wind generated by pulse current to accelerate dislocation slip, promote dislocation annihilation during slip process, reduce the number of dislocation defects in A508-3 steel, repair the radiation embrittlement damage of the pressure vessel, and improve the A508- 3 steel toughness, which is completely different from the principle of traditional annealing heat treatment to eliminate dislocation defects. More importantly, the pulse current can process the embrittlement hardening material "in situ", which has the advantages that the traditional annealing treatment does not have, and the temperature rise caused by the pulse current applied in this patent is only 80~350℃, that is It can eliminate dislocation defects at lower temperature than traditional heat treatment, consume less energy, and realize "green manufacturing". In addition to the above two advantages, the treatment time of the pulse current applied in this patent is only 5min~10h, which is far lower than the 168h heat treatment described in the literature, which can significantly reduce the time required to restore the properties of aging and embrittled A508-3 steel. The repair time is within the allowable range of the reactor shutdown and maintenance time window, and the influence on the normal production operation of the nuclear reactor is avoided. The invention reduces the number of dislocation defects in the embrittled and hardened A508-3 steel by precisely controlling the pulse current parameters and the pulse current processing time, so as to restore the toughness, thereby ensuring the safe operation of the nuclear power plant and prolonging the service of the pressurized water reactor nuclear power plant life.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a non-traditional treatment method, that is, a method for restoring and regenerating the properties of hardened and embrittled A508-3 steel under the action of pulse current. This method can eliminate the hardening and embrittlement damage of A508-3 steel caused by high-energy neutron irradiation and thermal aging, so that the properties of damaged materials can be recovered to a great extent, so as to achieve the purpose of extending the service life of pressure vessels in nuclear power plants. .

The composition of the invention is as follows: pulse current is applied to the material whose performance is aging and embrittled due to dislocation defects, and the parameters of the pulse current are controlled as follows: frequency 1~2000Hz, pulse width 20μs~1ms, current 10~5000A, action time 5min~10h. The pulse current can reduce the dislocation defects in the matrix of the aging embrittlement material and improve the Charpy impact toughness of the material, so as to achieve the purpose of repairing the radiation embrittlement hardening damage of A508-3 steel.

A method for eliminating the defects of A508-3 steel and improving the Charpy impact toughness of the material. The aging and embrittled A508-3 steel is subjected to pulse current treatment. The parameter range of the pulse current treatment is: frequency 1~2000Hz, pulse width 20μs~ 1ms, current 10~5000A, action time 5min~10h.

Further, in the described method for eliminating hardening and embrittlement of A508-3 steel by pulse current, the specific steps of the pulse current treatment are composed of the following:

(1) Determine the dislocation density and sample size of the aged and embrittled A508-3 steel, and determine the pulse current parameters and pulse current action time and other parameters according to the evaluated dislocation density and sample size of the A508-3 steel.

(2) Fix the aged and embrittled A508-3 steel on the pulse power supply with a fixture, and perform pulse current treatment according to the planned parameters and time.

According to the dislocation density and size of the A508-3 steel sample, select the appropriate pulse current parameters and pulse current treatment duration:

A508-3 steel aged and embrittled, the dislocation density is 1.26×10 ¹⁴ m ^-2 , the size is 0.5×5×25mm, the pulse current parameters are selected as 190Hz, 180μs, 195A, and the action time is 1h;

A508-3 steel aged and embrittled, the dislocation density is 1.26×10 ¹⁴ m ^-2 , the size is 1×10×25mm, the pulse current parameters are selected as 500Hz, 20μs, 175A, and the action time is 30min;

The aging and embrittled A508-3 steel has a dislocation density of 5.41×10 ¹³ m ^-2 and a size of 1.5×10×30mm. The pulse current parameters are selected as 500Hz, 84μs, 800A, and the action time is 5min.

When the method is applied to the actual reactor pressure vessel, the larger the size of A508-3 steel, the larger the frequency, the larger the pulse width, the larger the current and the longer the action time, and the action time is 2h-10h.

The equipment used in the pulse current processing is all pulse power supplies.

The pulse current treatment of the aged and embrittled A508-3 steel is carried out at room temperature.

The beneficial effects of the present invention are as follows:

1. Compared with the existing method for eliminating the aging embrittlement of A508-3 steel, the present invention can process the aging embrittlement A508-3 steel "in situ", so that the aging embrittlement has occurred. The properties of A508-3 steel are restored;

2. The present invention can also reduce the temperature required to eliminate aging and embrittlement of A508-3 steel to a certain extent, save energy, and realize green manufacturing.

Description of drawings

Fig. 1 is the A508-3 steel pulse current treatment selected in Example 2 before the dislocation defect quantity morphological diagram;

Fig. 2 is the A508-3 steel pulse current treatment selected by Example 2, the number and shape of dislocation defects;

Figure 3 is a comparison chart of Charpy impact absorption energy before and after the pulse of the A508-3 steel selected in Example 2 at -100 ^o C.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. On the contrary, the present invention covers any alternatives, modifications, equivalents and arrangements within the spirit and scope of the present invention as defined by the appended claims. Further, in order to give the public a better understanding of the present invention, some specific details are described in detail in the following detailed description of the present invention. The present invention can be fully understood by those skilled in the art without the description of these detailed parts.

The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but it is not intended to limit the present invention. The following is the best embodiment of the present invention:

Example 1:

In this example, pulse current treatment is performed on aged and embrittled A508-3 steel with a dislocation density of 1.26×10 ¹⁴ m ^-2 and a size of 0.5×5×25 mm. The specific steps are as follows:

The first step: According to the dislocation density and sample size of A508-3 steel, determine the parameter range of the pulse current. After optimizing the parameters, the optimal pulse current parameters are determined to be 190Hz, 180μs, 195A, and the action time is 1h.

The second step: Fix the aged and embrittled A508-3 steel at both ends of the output of the pulse power supply with a clamp, and carry out the pulse power treatment for 1h at room temperature.

The third step: use XRD to detect the material after pulse current treatment, obtain the full width at half maximum of each diffraction peak, and then calculate the dislocation density of the sample after pulse current treatment, and compare it with the dislocation density of the sample before pulse current treatment. As shown in Table 1, after adopting the pulse current treatment method of the present invention, the dislocation defects in the aged and embrittled A508-3 steel are eliminated to a certain extent.

Step 4: Referring to the standard GB/T 229-2007, prepare a 55×10×5mm Charpy impact test sample, perform the Charpy impact test at –100 ^o C, and record the Charpy of the sample before and after pulse current treatment at –100 ^o C shock absorption energy.

Example 2:

As shown in Fig. 1-Fig. 2, in this embodiment, pulse current treatment is performed on aged and embrittled A508-3 steel with a dislocation density of 1.26×10 ¹⁴ m ^-2 and a size of 1×10×25 mm. The specific steps are as follows:

The first step: According to the sample size of A508-3 steel, determine the parameter range of the pulse current, go through the optimization parameters, and determine that the optimal pulse current parameters are 500Hz, 20μs, 175A, and the action time is 30min.

Step 2: Fix the aged and embrittled A508-3 steel with clamps at both ends of the output of the pulse power supply, and perform pulse current treatment for 30 minutes at room temperature.

The third step: use XRD to detect the material after pulse current treatment, obtain the full width at half maximum of each diffraction peak, and then calculate the dislocation density of the sample after pulse current treatment, and compare it with the dislocation density of the sample before pulse current treatment. As shown in Table 1, after adopting the pulse current treatment method of the present invention, the dislocation defects in the aged and embrittled A508-3 steel are eliminated to a certain extent.

Step 4: Referring to the standard GB/T 229-2007, prepare a 55×10×5mm Charpy impact test sample, perform the Charpy impact test at –100 ^o C, and record the Charpy of the sample before and after pulse current treatment at –100 ^o C shock absorption energy.

Example 3:

In this example, pulse current treatment is performed on aged and embrittled A508-3 steel with a dislocation density of 5.41×10 ¹³ m ^-2 and a size of 1.5×10×30 mm. The specific steps are as follows:

The first step: According to the sample size of A508-3 steel, determine the parameter range of the pulse current, optimize the parameters, and determine the optimal pulse current parameters are 500Hz, 84μs, 800A, and the action time is 5min.

The second step: Fix the aged and embrittled A508-3 steel at both ends of the output of the pulse power supply with a clamp, and perform a pulse current treatment for 5 minutes at room temperature.

The third step: use XRD to detect the material after pulse current treatment, obtain the full width at half maximum of each diffraction peak, and then calculate the dislocation density of the sample after pulse current treatment, and compare it with the dislocation density of the sample before pulse current treatment. As shown in Table 1, after adopting the pulse current treatment method of the present invention, the dislocation defects in the aged and embrittled A508-3 steel are eliminated to a certain extent.

Step 4: Referring to the standard GB/T 229-2007, prepare a 55×10×5mm Charpy impact test sample, perform the Charpy impact test at –100 ^o C, and record the Charpy of the sample before and after pulse current treatment at –100 ^o C shock absorption energy.

The variation of dislocation density in the selected A508-3 steel for the embodiment of table 1

Samples treated with pulsed current (m^-2) Example 1 9.61×10¹³ Example 2 6.26×10¹³ Example 3 3.55×10¹³

The above is only the best specific embodiment of the A508-3 steel sample of the present invention. In the present invention, the time range of 5min-2h is based on the sample size range of the laboratory A508-3 steel. The specific application In actual production, the pulse current treatment time of A508-3 steel varies with the size of the steel itself, and the upper limit of the maximum applied current time is 10h.

The scope of protection of the present invention is not limited to the above-mentioned embodiments. Any person skilled in the art, within the technical scope disclosed by the present invention, can equivalently replace similar materials, equipment or adjust related materials according to the technical solution of the present invention and its inventive concept. All technical parameters should be covered within the protection scope of the present invention.

Claims (10)

1. a kind of method that pulse current eliminates A508-3 steel aging embrittlement, the method carries out the A508-3 steel of aging embrittlement Pulsed current annealing, the A508-3 steel is for manufacturing reactor pressure vessel, which is characterized in that the pulsed current annealing Parameter area: 1~2000Hz of frequency, pulsewidth 20 μ s~1ms, 10~5000A of electric current, action time 5min~10h, the method The dislocation defects quantity of the A508-3 steel of the embrittlement of aging is greatly lowered.

2. eliminating the method for A508-3 steel aging embrittlement as described in claim 1, which is characterized in that at the pulse current Specific step is managed to be made of following:

(1) dislocation density and sample size for determining aging A508-3 steel, according to the dislocation density and sample of determining A508-3 steel Product size determines pulse current parameter and pulse current action time parameter；

(2) the A508-3 steel of aging is fixed on to the output both ends of the pulse power with fixture, is continuously applied pulse until when corresponding Between.

3. eliminating the method for A508-3 steel aging embrittlement as claimed in claim 2, which is characterized in that according to the position of A508-3 steel Dislocation density and sample size select suitable pulse current parameter and pulse current action time:

The A508-3 steel of aging embrittlement, dislocation density are 1.26 × 10¹⁴m^-2, having a size of 0.5 × 5 × 25mm, pulse current parameter It is selected as 190Hz, 180 μ s, 195A, action time 1h.

4. eliminating the method for A508-3 steel aging embrittlement as claimed in claim 2, which is characterized in that according to the position of A508-3 steel Dislocation density and sample size select suitable pulse current parameter and pulse current action time:

The A508-3 steel of aging embrittlement, dislocation density are 1.26 × 10¹⁴m^-2, having a size of 1 × 10 × 25mm, the choosing of pulse current parameter It is selected as 500Hz, 20 μ s, 175A, action time 30min.

5. eliminating the method for A508-3 steel aging embrittlement as claimed in claim 2, which is characterized in that according to the position of A508-3 steel Dislocation density and sample size select suitable pulse current parameter and pulse current action time:

The A508-3 steel of aging embrittlement, dislocation density are 5.41 × 10¹³m^-2, having a size of 1.5 × 10 × 25mm, pulse current parameter It is selected as 500Hz, 84 μ s, 800A, action time 5min.

6. eliminating the method for A508-3 steel aging embrittlement as claimed in claim 2, which is characterized in that according to the position of A508-3 steel Dislocation density and sample size select suitable pulse current parameter and pulse current action time:

When the method is applied to real reaction core pressure vessel, A508-3 steel dimensions are bigger, and frequency is bigger, and pulsewidth is bigger, Electric current is bigger, and action time is longer, action time 2h-10h.

7. eliminating the method for A508-3 steel aging embrittlement as claimed in claim 2, which is characterized in that the method also includes steps Suddenly (3): by preparation Charpy-type test sample, to pulse, treated that material detects.

8. eliminating the method for A508-3 steel aging embrittlement as claimed in claim 7, which is characterized in that the step (3) is specific Include:

3-1: detecting the material after pulsed current annealing using XRD, obtains the halfwidth of each diffraction maximum, and then calculate The dislocation density of sample after pulsed current annealing, is compared with the dislocation density of sample before pulsed current annealing；

3-2: reference standard GB/T 229-2007, Charpy-type test sample is prepared, in -100 DEG C of progress Charpy-type tests, The Charpy impact energy of pulsed current annealing front and back sample at -100 DEG C of record.

9. eliminating the method for A508-3 steel aging embrittlement as described in claim 1, which is characterized in that the pulsed current annealing Used equipment is the pulse power.

10. eliminating the method for A508-3 steel aging embrittlement as described in claim 1, which is characterized in that the A508-3 steel Pulsed current annealing is carried out to carry out at room temperature.