CN103014260B - Method for eliminating low-temperature aging brittleness of duplex stainless steel - Google Patents
Method for eliminating low-temperature aging brittleness of duplex stainless steel Download PDFInfo
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- CN103014260B CN103014260B CN2013100017845A CN201310001784A CN103014260B CN 103014260 B CN103014260 B CN 103014260B CN 2013100017845 A CN2013100017845 A CN 2013100017845A CN 201310001784 A CN201310001784 A CN 201310001784A CN 103014260 B CN103014260 B CN 103014260B
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Abstract
The invention belongs to the field of heat treatment for metal materials, and particularly relates to a method for eliminating the low-temperature aging brittleness of duplex stainless steel. Annealing heat treatment is performed on the duplex stainless steel which serves in a temperature range from 300 to 500 DEG C for a long time under the process conditions of a temperature range from 520 to 620 DEG C and an annealing time of 30-90 minutes. After annealing according to the method, the low-temperature brittleness caused by long-time aging is eliminated, and the mechanical properties of the hardness and the impact and the like of the material are returned to the state before the long-time aging.
Description
Technical field
The invention belongs to the metallic substance Field of Heat-treatment, be specifically related to a kind of method of eliminating duplex stainless steel low temperature aging fragility.
Background technology
The Nuclear power plants that China has moved and be about to build adopts pressurized-water reactor mostly, what pressurized-water reactor nuclear power plant primary coolant circuit pipe and main pump shell adopted is duplex stainless steel, it has good heat resistanceheat resistant crackle, corrosion-resistant, stress-corrosion-cracking resistance, has good mechanical property simultaneously.But, at the duplex stainless steel of 300 ~ 500 ℃ of temperature range long services, because the variation in ferrite can cause aged brittleness, the degree of embrittlement and the ferrite content in material and aging temp (using temperature) are closely related.The aged brittleness of duplex stainless steel has brought potential safety hazard on the one hand the operation of parts, has also greatly shortened its work-ing life on the other hand.
The method of traditional elimination low temperature aging fragility, be duplex stainless steel to be reheated to 1000 ~ 1100 ℃ carry out solution treatment again, and the fragility that Long-term Aging is generated again is dissolved in matrix and goes mutually.This method may cause the distortion of part, simultaneously due to the needs High Temperature Furnaces Heating Apparatus, can waste the more energy.In addition, under solid solubility temperature, ferritic content can reduce, thereby causes the intensity of material to reduce than virgin state.Therefore, the method for solution treatment is only applicable to not too important parts again.
From phasor, there is a kind of fragility phase of the σ of being called phase 500 ~ 1000 ℃ of temperature ranges, if adopt low-temperature annealing to process, the existence of σ phase can make the mechanical property of material significantly worsen equally.Therefore, it is conventionally believed that duplex stainless steel will avoid heat-treating in this temperature range.The σ phase separate out with material in ferritic content and heat treated temperature and time closely related, the present invention, by accurately controlling temperature range and the time range of annealing, can avoid the generation of σ phase fully.Carry out the low-temperature annealing processing in 520 ~ 620 ℃ of scopes, the fragility phase decomposition that can make the low temperature Long-term Aging generate, can not generate the σ phase simultaneously, the shortcoming of the part deformation that lower temperature has also avoided pyroprocessing to cause simultaneously, therefore, anneal use range under lesser temps is more extensively sent out, and is the optimal selection of eliminating duplex stainless steel low temperature aging fragility.
Summary of the invention
The object of the present invention is to provide a kind of method of eliminating duplex stainless steel low temperature aging fragility, the low temperature brittleness of utilizing the method can make Long-term Aging cause eliminates, make the mechanical property of material be returned to the front state of Long-term Aging, thereby reach the purpose increased the service life.
Formation of the present invention: the duplex stainless steel generation timeliness embrittlement after 300 ~ 500 ℃ of uses for a long time by 520 ~ 620 ℃ of annealing 30 ~ 90 minutes, makes the fragility phase decomposition produced in ferrite, thereby reaches the purpose of eliminating aged brittleness.
A kind of method of eliminating duplex stainless steel low temperature aging fragility, carry out anneal to described duplex stainless steel, and the temperature range of described anneal is 520 ~ 620 ℃, and annealing time is 30 ~ 90 minutes.
Further, the method for described elimination duplex stainless steel low temperature aging fragility, described anneal specifically comprises the following steps:
(1) measure ferrite content and the thickness of steel part, according to the ferrite content recorded and thickness, determine the processing parameter of annealing;
(2) the two-phase stainless steel part is put into to annealing device and carry out anneal, select argon gas as shielding gas, after anneal, adopt Water Quenching or air cooling to process.
The temperature range of coming selective annealing to process according to ferritic content in duplex stainless steel: ferrite content is less than 25%, and annealing temperature is selected 550 ~ 620 ℃; Ferrite content is between 25% ~ 50%, and annealing temperature is selected 540 ~ 580 ℃; Ferrite content is greater than 50%, and annealing temperature is selected 520 ~ 550 ℃.
Carry out the time range of selective annealing processing by temperature according to the aging temp of two-phase stainless steel part: aging temp is lower than 350 ℃, and annealing time is selected 30 ~ 45 minutes; Aging temp is between 350 ~ 450 ℃, and annealing time is selected 45 ~ 60 minutes; Aging temp is higher than 450 ℃, and annealing time is selected 60 ~ 90 minutes.
The equipment that described anneal adopts is a kind of in chamber type electric resistance furnace, tube type resistance furnace or vacuum annealing furnace.
Described anneal is carried out under vacuum or inert atmosphere.
Carry out the technique after selective annealing is processed according to the size of two-phase stainless steel part after anneal; Thickness is less than 100 millimeters, after anneal, adopts air cooling to process; Thickness is greater than 100 millimeters, adopts Water Quenching after anneal, and the time is 15 ~ 30 minutes, and water temperature is lower than 40 ℃.
Advantage of the present invention is to compare with the method for existing elimination low temperature aging fragility, the present invention adopts the annealing process lower than solid solubility temperature, can make the mechanical property of material be returned to virgin state, lower annealing temperature has avoided parts to deform simultaneously, and this has also saved mass energy simultaneously.
Embodiment
Embodiment 1:
The present embodiment is to carrying out anneal at certain two-phase stainless steel part of 10,000 hours of 400 ℃ of timeliness.Step is as follows:
The first step.Ferrite content and the thickness of measuring steel part are respectively 15% and 150 millimeter, determine that the processing parameter of annealing is: 550 ~ 620 ℃, 45 ~ 60 minutes, adopt Water Quenching after anneal.
Second step.The two-phase stainless steel part is put into to chamber type electric resistance furnace 550 ℃ of anneal of carrying out 60 minutes, select argon gas as shielding gas, adopt Water Quenching after anneal, the time is 20 minutes, 30 ℃ of water temperatures.
The 3rd step.After the mensuration anneal, the impact property of duplex stainless steel, contrasted with the impact property after nonageing state and timeliness.As shown in table 1, after adopting method for annealing of the present invention to process, the mechanical property of duplex stainless steel has been returned to unaged state.
Embodiment 2:
The present embodiment is to carrying out anneal at certain two-phase stainless steel part of 30,000 hours of 300 ℃ of timeliness.Step is as follows:
The first step.Ferrite content and the thickness of measuring steel part are respectively 20% and 25 millimeter, determine that the processing parameter of annealing is: 540 ~ 580 ℃, 30 ~ 45 minutes, after anneal, adopt air cooling to process.
Second step.The two-phase stainless steel part is put into to tube type resistance furnace 580 ℃ of anneal of carrying out 30 minutes, select argon gas as shielding gas, after anneal, adopt air cooling to process, be placed on naturally cooling in air.
The 3rd step.After the mensuration anneal, the impact property of duplex stainless steel, contrasted with the impact property after nonageing state and timeliness.As shown in table 1, after adopting method for annealing of the present invention to process, the mechanical property of duplex stainless steel has been returned to unaged state.
Embodiment 3:
The present embodiment is to carrying out anneal at certain two-phase stainless steel part of 1,000 hours of 475 ℃ of timeliness.Step is as follows:
The first step.Ferrite content and the thickness of measuring steel part are respectively 52% and 50 millimeter, determine that the processing parameter of annealing is: 520 ~ 550 ℃, 60 ~ 90 minutes, after anneal, adopt air cooling to process.
Second step.The two-phase stainless steel part is put into to vacuum annealing furnace 550 ℃ of anneal of carrying out 60 minutes, after anneal, adopt air cooling to process.
The 3rd step.After the mensuration anneal, the impact property of duplex stainless steel, contrasted with the impact property after nonageing state and timeliness.As shown in table 1, after adopting method for annealing of the present invention to process, the mechanical property of duplex stainless steel has been returned to unaged state.
table 1 embodiment selects the variation of the ballistic work of duplex stainless steel
| ? | Nonageing | After Long-term Aging | After anneal |
| Embodiment 1 | 279.3±25.8J | 65.9±21.2J | 287.0±11.2J |
| Embodiment 2 | 353.8±11.4J | 149.8±11.0J | 352.1±20.6J |
| Embodiment 3 | 299.7±17.5J | 121.2±15.6J | 314.7±13.8J |
Claims (3)
1. a method of eliminating duplex stainless steel low temperature aging fragility, it is characterized in that: described duplex stainless steel is carried out to anneal, and the temperature range of described anneal is 520 ~ 620 ℃, and annealing time is 30 ~ 90 minutes; Described anneal specifically comprises the following steps:
(1) measure ferrite content and the thickness of steel part, according to the ferrite content recorded and thickness, determine the processing parameter of annealing; Carry out the time of selective annealing processing according to the aging temp of two-phase stainless steel part; Wherein, the temperature range of coming selective annealing to process according to ferritic content in duplex stainless steel:
Ferrite content is less than 25%, and annealing temperature is selected 550 ~ 620 ℃;
Ferrite content is between 25% ~ 50%, and annealing temperature is selected 540 ~ 580 ℃;
Ferrite content is greater than 50%, and annealing temperature is selected 520 ~ 550 ℃;
Carry out the time range of selective annealing processing according to the aging temp of two-phase stainless steel part:
Aging temp is lower than 350 ℃, and annealing time is selected 30 ~ 45 minutes;
Aging temp is between 350 ~ 450 ℃, and annealing time is selected 45 ~ 60 minutes;
Aging temp is higher than 450 ℃, and annealing time is selected 60 ~ 90 minutes;
(2) the two-phase stainless steel part is put into to annealing device and carry out anneal, select argon gas as shielding gas, after anneal, adopt Water Quenching or air cooling to process.
2. the method for claim 1 is characterized in that: the equipment that described anneal adopts is a kind of in chamber type electric resistance furnace, tube type resistance furnace or vacuum annealing furnace.
3. the method for claim 1, is characterized in that: after anneal, according to the size of two-phase stainless steel part, carry out the technique after selective annealing is processed;
Thickness is less than 100 millimeters, after anneal, adopts air cooling to process;
Thickness is greater than 100 millimeters, adopts Water Quenching after anneal, and the time is 15 ~ 30 minutes, and water temperature is lower than 40 ℃.
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| CN104181096A (en) * | 2014-09-09 | 2014-12-03 | 北京科技大学 | Method for evaluating thermal ageing state of duplex stainless steel by use of thermoelectric potential |
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| CN108315549B (en) * | 2018-03-19 | 2019-12-24 | 北京科技大学 | Method for regenerating aged duplex stainless steel performance under action of pulse current |
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| JP3921926B2 (en) * | 2000-07-13 | 2007-05-30 | Ｊｆｅスチール株式会社 | Method for producing martensitic stainless steel |
| CN100516274C (en) * | 2007-08-20 | 2009-07-22 | 江阴市江东不锈钢制造有限公司 | 03Cr22Ni4NbN austenite-ferritic stainless steel and production technology therefor |
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