CN102758141A - Novel nitride-reinforced martensite heat-resisting steel - Google Patents
Novel nitride-reinforced martensite heat-resisting steel Download PDFInfo
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- CN102758141A CN102758141A CN2011101030104A CN201110103010A CN102758141A CN 102758141 A CN102758141 A CN 102758141A CN 2011101030104 A CN2011101030104 A CN 2011101030104A CN 201110103010 A CN201110103010 A CN 201110103010A CN 102758141 A CN102758141 A CN 102758141A
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Abstract
The invention provides a novel nitride-reinforced martensite heat-resisting steel. The steel is characterized in that main alloy components of the martensite heat-resisting steel comprises, by weight, 0.8-1.5% of Mn; 8.0-10.0% of Cr; no more than 1.5% of W; no more than 1.5% of Mo (wherein wherein the sum of the weight percentages of W and Mo is 1.5-2.0%); no more than 0.06% of Nb; no more than 0.15% of Ta (wherein Nb+Ta accounts for 0.05-0.15%); 0.1-0.3% of V; 0.03-0.05% of N; and balance of Fe. According to the invention, the content of the element Mn is increased. On a basis that a phase change point of a material AC1 is almost not reduced, heat-resisting steel original martensite tissues reinforced by high-thermal-stability nitride precipitate is obtained. With the controlling over the contents of elements Co, W, Mo, N, and the like, Laves phase and Z phase precipitation of steel during long-term high-temperature service can be retarded. Therefore, the obtained steel has relatively high tissue stability and good high-temperature mechanical properties.
Description
Technical field
The present invention relates to iron-based high temperature steel technical field, a kind of novel nitride strengthening martensite high temperature steel is provided especially.
Background technology
Improve steam parameter, developing overcritical is to improve coal fired power generation efficient with the ultra supercritical generation technology, reduces the effective measure of carbon emission, in worldwide, is greatly developed at present.Along with the raising of steam parameter, its key part (like main steam line) with the heat resistant structure material harsh more requirement has been proposed.At present, the power station mainly contains T/P91, T/P92, P122 etc. with advanced ferrite/martensite high temperature steel.
Experimental study when advanced ferrite/martensite high temperature steel (like T/P91, T/P92, P122 etc.) having been carried out high temperature length abroad, as shown in Figure 1, and studied the tissue of material under this condition and the relation of mechanical property.The result shows, along with the increase of active time, occurs an intensity on the intensity of the high temperature steel of high-alloying-rupture time curve and falls the zone suddenly, be i.e. middle stressed zone among Fig. 2.This falls the zone suddenly and causes the reason of over-evaluating advanced ferrite/martensite high temperature steel such as P92, P122 (as 100,000 hours) creep rupture strength when long at present in the world just.General with the short-term test data-speculative creep rupture life when long, all adopt the straight-line extrapolation method to carry out, and this intensity is fallen the existence in zone suddenly and is made the bigger error of straight-line extrapolation existence commonly used.600 ℃ of creep rupture strengths of 100,000 hours of P92 steel for example, the extrapolated value that Japanese Nippon Steel provides is 132MPa, and has formulated the ASME standard according to this; And the European creep council is 115MPa according to the extrapolated value that experimental result of its longer time provides.Thereby make the overcritical power plant that respectively uses the P92 material to build have to reduce the parameter operation, caused great financial loss.
Further research shows, it is the major cause that stressed zone intensity is fallen suddenly in causing that high temperature steel is organized unstability.Therefore how to obtain the high ferrite/martensite high temperature steel of structure stability and be to improve high temperature steel key of mechanical property under hot conditions when long.For ferrite/martensite high temperature steel, because the singularity of high temperature steel under the high temperature service condition and the complicacy of microstructure evolution, the structure stability when improving its length under the hot conditions needs the understanding of following two levels.
The first, original structure will have advantages of higher stability.The original structure structure of the normalizing+tempering attitude of the advanced ferrite/martensite high temperature steel of tradition is as shown in Figure 3, is mainly the precipitated phase that distributing on the martensitic matrix (carbide and nitride).Wherein precipitated phase mainly contains M
23C
6Type and MX type, M
23C
6Type mainly be (Cr, Fe)
23C
6, MX type precipitated phase is mainly NbC, VC, NbN, VN, TaN etc.M wherein
23C
6The type precipitated phase mainly is distributed on the original austenite crystal prevention and lath circle of martensitic matrix, and MX type precipitated phase mainly is distributed in the lath.Yet satisfying under the ideal stoicheiometry condition, the thermostability of carbide and nitride is different, and the thermostability of nitride will generally be higher than the thermostability of carbide.Based on this theory, the Japanology scholar has designed the microstructure of nitride strengthening martensite high temperature steel, and is as shown in Figure 4, and successfully develops nitride strengthening martensite high temperature steel 9Cr3W3CoNbN.
The second, slow down when long thick precipitated phase in the structure of steel in the military service process, mainly be Laves mutually with Z separating out mutually.Laves is mainly Fe mutually
2W and Fe
2Mo, Z are mainly CrNbN mutually.They are easy to alligatoring in the military service process of steel, size is all bigger, and are less to the stabilizing tissue effect.Along with growing up of its size, can consume effective W, Mo solid solution element content and nitride in the steel on the contrary respectively, bring out the creep hole, therefore must delay separating out of they as far as possible.
Yet there is a fatal shortcoming in the nitride strengthening martensite high temperature steel 9Cr3W3CoNbN of Japanese scholar's research and development, is exactly to form a large amount of Co, the W element that delta ferrite adds in order to suppress owing to the reduction of carbon content in the steel.But the Co element can promote the alligatoring of Laves phase strongly, and the W element also can promote separating out and alligatoring of Laves phase as the forming element of Laves phase as non-Laves phase forming element.Thick Laves meets and brings out the creep cavity in the steel, the high-temperature behavior of infringement material.
Summary of the invention
The object of the present invention is to provide a kind of novel nitride strengthening martensite high temperature steel, to solve the problem of the high temperature resistant structure stability difference of martensite high temperature steel in the past.
The invention provides a kind of novel nitride strengthening martensite high temperature steel, it is characterized in that: the main alloying constituent (weight percent) of said martensite high temperature steel is Mn:0.8～1.5%; Cr:8.0～10.0%; W :≤1.5%; Mo :≤1.5%; And W+Mo:1.5～2.0%; Nb :≤0.06%; Ta :≤0.15%; And Nb+Ta:0.05～0.15%; V:0.1～0.3%; N:0.03 ~ 0.05%; Fe: surplus.
Wherein, described martensite high temperature steel can also contain following composition (weight percent) and is: C :≤0.005%; Si :≤0.5%; S :≤0.005%; P :≤0.005%; Co :≤1.5%; O :≤0.0010%; Ni :≤0.01%; Al: < 0.01%; Ti: < 0.005%; Cu: < 0.01%.
Novel nitride strengthening martensite high temperature steel provided by the invention, the weight percent of its composition V is preferably 0.15～0.3%, and the weight percent of composition Mo is preferably Mo :≤0.5%.
Novel nitride strengthening martensite high temperature steel provided by the invention has following characteristic:
(1) carbon content that reduces in the martensite high temperature steel arrives extremely low-level (≤0.005%) to suppress the formation of carbide in the steel;
When the carbon content in the martensite high temperature steel be reduced to extremely low-level after, no longer form carbide in the martensite high temperature steel, and obtain the tissue of nitride precipitation strength completely.
(2) add elements such as Nb, Ta, V in the martensite high temperature steel and form nitride;
Because the bonding force of Ti and N is extremely strong, so should strictness control the content of Ti element in the steel, be mingled with in order to avoid under the situation of high nitrogen-containing, form TiN.And mainly add elements such as Nb, Ta, V to form the high nitride precipitated phase of thermostability.
(3) improve manganese content to 0.8～1.5% in the martensite high temperature steel
Increase Mn content to 0.8～1.5% in the steel, can effectively suppress the formation of delta ferrite, guarantee to obtain whole martensitic stuctures.The Mn element is suppressing two advantages of having used of delta ferrite formation than Co, W element: the first, and the Mn element can not promote Laves phase and Z formation mutually in the steel; The second, the add-on of Mn element is controlled in this scope, can significantly not reduce the A of material
C1Transformation temperature.
(4) S content must be extremely low in the martensite high temperature steel, is controlled at below the 20ppm;
Because the raising of manganese content in the martensite high temperature steel is prone to form MnS with S and is mingled with, and has both damaged the high-temperature behavior of material, has reduced the effect of solid solution manganese again.
(5) Co, (W+Mo) content are controlled at respectively below 1.5% and 2.0% in the martensite high temperature steel
Separate out mutually in order to slow down the Laves of martensite high temperature steel in the Long-term Service under High Temperature process, see, must reduce Co, W, the Mo content in the steel from separating out the kinetics angle.
(6) N content is controlled at below 0.05% in the martensite high temperature steel;
Separate out mutually in order to slow down the Z of martensite high temperature steel in the Long-term Service under High Temperature process, see, must guarantee that elements such as Nb, Ta, V form under the prerequisite of nitride, reduce the N content in the martensite high temperature steel as far as possible from separating out the kinetics angle.
The concrete preparation method of martensite high temperature steel provided by the invention is conventional vacuum metling, and wherein, concrete thermal treatment process is normalizing+tempering, impact of using in the experiment and tension specimen, and its normalizing temperature is 980 ± 10 ℃, tempering temperature is 750 ± 10 ℃; And martensite high temperature steel is whole martensitic stuctures under as-normalized condition, and carbides-free is separated out in the tissue, has only very tiny nitride on original austenite crystal prevention and lath circle, to separate out.
Novel nitride strengthening martensite high temperature steel provided by the invention is a kind of very novel novel martensite heat-resisting steel material, can be used as important heat resistant structure steel and is used for each efficient power generation factory, like ultra supercritical thermal power plant, Nuclear power plants etc.
Novel nitride strengthening martensite high temperature steel provided by the invention through increasing the Mn constituent content, is reducing materials A hardly
C1Under the prerequisite of transformation temperature; Acquisition is by the original martensitic stucture of high temperature steel of the high nitride precipitation strength of thermostability; And content through elements such as Co, W, Mo, N in the control steel; Slow down the Laves of steel in the Long-term Service under High Temperature process and separate out mutually with Z mutually, therefore can obtain higher structure stability, have mechanical behavior under high temperature preferably.
Description of drawings
Fig. 1 is each advanced jessop lasting experimental result when long;
Fig. 2 is three zones on the advanced jessop endurance curve;
Fig. 3 is the microstructure synoptic diagram of traditional martensite high temperature steel;
Fig. 4 is the microstructure synoptic diagram of novel nitride strengthening martensite high temperature steel among the present invention;
Fig. 5 is the tissue topography of martensite high temperature steel among the embodiment 1: martensite+delta ferrite;
Fig. 6 is the tissue topography of martensite high temperature steel among the embodiment 2: martensite;
Fig. 7 is the tissue topography of martensite high temperature steel among the embodiment 3: martensite;
Fig. 8 is the tissue topography of martensite high temperature steel among the embodiment 4: martensite;
Fig. 9 is the tissue topography of martensite high temperature steel among the embodiment 5: martensite;
The nitride synoptic diagram that Figure 10 separates out for disperse in the martensite high temperature steel among the embodiment 3;
Figure 11 is the microstructure synoptic diagram of martensite high temperature steel behind 600 ℃ of timeliness 500h among the embodiment 3;
Figure 12 is the microstructure synoptic diagram of martensite high temperature steel behind 600 ℃ of timeliness 1000h among the embodiment 3;
Figure 13 is the microstructure synoptic diagram of martensite high temperature steel behind 600 ℃ of timeliness 1700h among the embodiment 3.
Embodiment
Following embodiment will further explain the present invention, but therefore not limit the present invention.
Embodiment 6
Martensite high temperature steel among embodiment 1～embodiment 5 is carried out the test of martensitic stucture performance:
Not increase of Mn content in the martensite high temperature steel maintains 0.5% level among the embodiment 1, and it organizes as shown in Figure 4, after visible carbon content reduces, will not generate delta ferrite if do not increase the content of Mn.
The microstructure of martensite high temperature steel is as shown in Figure 5 among the embodiment 2, after visible carbon content reduces, increases Mn content to 0.8% and can suppress delta ferrite, obtains whole martensitic stuctures.
Do not add Ta among the embodiment 3 in the martensite high temperature steel, and added the Nb element, its microstructure is as shown in Figure 6, is whole martensitic stuctures.
Do not add Ta among the embodiment 4 in the martensite high temperature steel, and added the Nb element, group is micro-knits as shown in Figure 7ly for it, is whole martensitic stuctures.
Add 0.09% Ta and 0.06% Nb element among the embodiment 5 in the martensite high temperature steel, its microstructure is as shown in Figure 8, is whole martensitic stuctures.
Be example with the precipitated phase in the martensite high temperature steel among the embodiment 3 among Fig. 9, provided the microscopic appearance of precipitated phase, precipitated phase is uniform distribution and is of a size of the nitride below the 50nm.
Martensite high temperature steel among embodiment 1～embodiment 5 is carried out the test (specifically seeing table 2, table 3) of mechanical property:
Among conclusion: the embodiment 1 in the martensite high temperature steel owing to Mn content is crossed the low delta ferrite that generated, so its impelling strength is relatively poor.In the martensite high temperature steel Mn content is increased to 0.8% among the embodiment 2 and just can obtains whole martensitic stuctures, thereby the nitride strengthening martensite high temperature steel composition in the proof claim can guarantee to obtain whole martensitic stuctures.But the Ta content that adds in the martensite high temperature steel among the embodiment 2 is lower, and does not add another nitride forming element Nb, and this moment, the impelling strength of steel was very poor.
Comparative example 3 and embodiment 4 can find out, because the Mn content of martensite high temperature steel is low than martensite high temperature steel among the embodiment 4 among the embodiment 3, so its transformation temperature A
C1High than the NS4 steel, thereby, simultaneously when 700 ℃ of tempering among the embodiment 4 in the martensite high temperature steel tissue can obtain abundant tempering, and all have higher impelling strength under with-20 ℃ in room temperature.And among the embodiment 3 martensite high temperature steel because A
C1Temperature is high, and therefore comparatively speaking, tempering temperature is just not high enough, so can only at room temperature have higher impelling strength, the impelling strength extreme difference under-20 ℃ of low temperature.Comparative example 3,4 and 5 can find out, when further improving tempering temperature to 750 ℃, the impact property of steel further improved.Comprehensive this 2 point, nitride strengthening Heat Treatment Of Steel technology is decided to be: normalizing+tempering, normalizing temperature are 980 ± 10 ℃, tempering temperature is 750 ± 10 ℃.
The high-temperature short delay stretching mechanical property of martensite high temperature steel is as shown in table 3 among the embodiment, and visible novel nitride strengthening martensite high temperature steel has higher tensile strength in short-term.Can know that from Fig. 2 the control material long term rupture strength is YIELD STRENGTH in the fs of area of high stress.Visible from the data of table 2 and table 3; The room temperature of novel nitride strengthening martensite high temperature steel and high temperature tensile strength and present ultra supercritical thermal power station being on close level with advanced jessop P92 steel; Therefore can predict, novel nitride strengthening martensite high temperature steel should have higher creep rupture strength in the fs of endurance curve.In addition; In the subordinate phase of endurance curve, promptly medium stage of stress is because the design of the stability tissue of novel nitride strengthening martensite high temperature steel; Promptly realize the disperse precipitation strength by the nitride of high thermal stability; Therefore in the subordinate phase of endurance curve, the trend of falling suddenly can not appear in novel nitride strengthening steel, thereby can have higher creep rupture strength.
Claims (6)
1. novel nitride strengthening martensite high temperature steel is characterized in that: the main alloying constituent (weight percent) of said martensite high temperature steel is Mn:0.8～1.5%; Cr:8.0～10.0%; W :≤1.5%; Mo :≤1.5%; And W+Mo:1.5～2.0%; Nb :≤0.06%; Ta :≤0.15%; And Nb+Ta:0.05～0.15%; V:0.1～0.3%; N:0.03 ~ 0.05%; Fe: surplus.
2. according to the described novel nitride strengthening martensite high temperature steel of claim 1, it is characterized in that: described martensite high temperature steel contains following composition (weight percent) and is: C :≤0.005%; Si :≤0.5%; S :≤0.005%; P :≤0.005%; Co :≤1.5%; O :≤0.0010%; Ni :≤0.01%; Al: < 0.01%; Ti: < 0.005%; Cu: < 0.01%.
3. according to the described novel nitride strengthening martensite high temperature steel of claim 1, it is characterized in that: the weight percent of V is 0.15～0.3% in the said martensite high temperature steel.
4. according to the described novel nitride strengthening martensite high temperature steel of claim 1, it is characterized in that: the weight percent of Mo is Mo in the said martensite high temperature steel :≤0.5%.
5. according to the described novel nitride strengthening martensite high temperature steel of claim 1, it is characterized in that: the thermal treatment process of said martensite high temperature steel is normalizing+tempering, and normalizing temperature is 980 ± 10 ℃, and tempering temperature is 750 ± 10 ℃.
6. according to the described novel nitride strengthening martensite high temperature steel of claim 3; It is characterized in that: said martensite high temperature steel is whole martensitic stuctures under as-normalized condition; Carbides-free is separated out in the tissue, has only very tiny nitride on original austenite crystal prevention and lath circle, to separate out.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104561839A (en) * | 2015-02-09 | 2015-04-29 | 中国第一重型机械股份公司 | Novel rare-earth modified 9% Cr martensitic heat resisting cast steel and manufacturing method thereof |
| CN111843285A (en) * | 2020-07-08 | 2020-10-30 | 武汉大学 | Welding wire for high-grade martensitic heat-resistant steel with anti-aging embrittlement welding line and application thereof |
| CN113025881A (en) * | 2021-02-04 | 2021-06-25 | 北京国电富通科技发展有限责任公司 | Martensite heat-resistant steel pipe fitting for ultra-supercritical unit |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS556458A (en) * | 1978-06-29 | 1980-01-17 | Nippon Steel Corp | Low alloy heat-resisting steel of improved creep brittleness resistance characteristic |
| CN1784503A (en) * | 2003-03-31 | 2006-06-07 | 独立行政法人物质·材料研究机构 | Welded joint of tempered martensite based heat-resistant steel |
-
2011
- 2011-04-25 CN CN2011101030104A patent/CN102758141A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS556458A (en) * | 1978-06-29 | 1980-01-17 | Nippon Steel Corp | Low alloy heat-resisting steel of improved creep brittleness resistance characteristic |
| CN1784503A (en) * | 2003-03-31 | 2006-06-07 | 独立行政法人物质·材料研究机构 | Welded joint of tempered martensite based heat-resistant steel |
Non-Patent Citations (1)
| Title |
|---|
| PINGHU ET AL.: "Nitride-strengthened reduced activation ferritic/martensitic steels", 《FUSION ENGINEERING AND DESIGN》 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104561839A (en) * | 2015-02-09 | 2015-04-29 | 中国第一重型机械股份公司 | Novel rare-earth modified 9% Cr martensitic heat resisting cast steel and manufacturing method thereof |
| CN111843285A (en) * | 2020-07-08 | 2020-10-30 | 武汉大学 | Welding wire for high-grade martensitic heat-resistant steel with anti-aging embrittlement welding line and application thereof |
| CN111843285B (en) * | 2020-07-08 | 2021-12-07 | 武汉大学 | Welding wire for high-grade martensitic heat-resistant steel with anti-aging embrittlement welding line and application thereof |
| CN113025881A (en) * | 2021-02-04 | 2021-06-25 | 北京国电富通科技发展有限责任公司 | Martensite heat-resistant steel pipe fitting for ultra-supercritical unit |
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Application publication date: 20121031 |