CN104451074A - Method for lowering intercrystalline corrosion susceptibility of Super304H heat-resistant steel - Google Patents
Method for lowering intercrystalline corrosion susceptibility of Super304H heat-resistant steel Download PDFInfo
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- CN104451074A CN104451074A CN201410782833.8A CN201410782833A CN104451074A CN 104451074 A CN104451074 A CN 104451074A CN 201410782833 A CN201410782833 A CN 201410782833A CN 104451074 A CN104451074 A CN 104451074A
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Abstract
The invention discloses a method for lowering intercrystalline corrosion susceptibility of Super304H heat-resistant steel. The method comprises the following steps: S1 carrying out homogenized solid solution pretreatment on a section of Super304H heat in a resistance-type thermal treatment furnace, so as to obtain a sample; S2 putting the sample pretreated in the step S1 into the resistance-type thermal treatment furnace to be softened, wherein the softening temperature is 1250-1300 DEG C, carrying out heat preservation for 20-60 minutes, and then carrying out water cooling, so as to obtain a softened sample; and S3 carrying out solid solution treatment on the softened sample obtained from the step S2 in the resistance-type thermal treatment furnace, and carrying out water cooling, so as to obtain a softened solid solution sample, wherein the solid solution pretreatment process and the solid solution treatment process are both heating in air at 1150 DEG C for 30 minutes and then carrying out water cooling to room temperature. According to the method disclosed by the invention, the intercrystalline corrosion resistance of the Super304H is improved; no reduction of high-temperature strength can be ensured; leakage or tube explosion accidents caused by intercrystalline corrosion are greatly reduced; and the security of thermal power generation is improved.
Description
Technical field
The present invention relates to a kind of method reducing Super304H high temperature steel Susceptibility To Intergranular Corrosion.
Background technology
Thermal power generation is that a kind of heat energy produced during the fuel combustions such as oil, coal and Sweet natural gas that utilizes heats water, and produces high-pressure steam, then is carried out the method that generates electricity by water vapour pushing generator group.The development experience of fired power generating unit is by low pressure, ultra-high voltage, subcritical, the overcritical course developed to extra-supercritical unit.Extra-supercritical unit refers to that interior vapor temperature is not less than 593 DEG C or vapor pressure is not less than 31Mpa, has the fired power generating unit of lower coal consumption amount and higher thermal efficiency.Extra-supercritical unit subjects vapor pressure higher than unit in the past and vapor temperature, and the material property of this high-temperature component such as the superheater to boiler, reheater proposes more and more higher requirement.
The eighties in 20th century, SUMITOMO CHEMICAL metal, on the stainless basis of traditional TP304H, takes the lead in developing heat resistance stainless steel Super304H, and is widely used in reheater tube and the superheater tube of extra-supercritical unit.From composition, Super304H steel improves C content on the stainless basis of traditional TP304H, reduces Mn, Si, Cr and Ni upper content limit, and adds the elements such as Cu, Nb, N.Difference on composition makes Super304H steel form M
23c
6(M=Fe, Cr), Nb (C, N), NbCrN and ε-Cu four kinds of main High-Temperature Strengthening precipitated phases mutually.These four kinds of precipitated phases can exist at different temperatures: M
23c
6(M=Fe, Cr) can almost all be solid-solution in matrix at T>=1000 DEG C; Nb (C, N) is only present in the sample of T≤1250 DEG C; ε-Cu mutually can in the sample of T≤1150 DEG C stable existence; NbCrN just can be detected in the sample of 1250 DEG C.These precipitated phases are worked in coordination, and form strong dispersion-strengthened action to Super304H steel, improve its hot strength.
Becoming a useful person in technique, the technique of becoming a useful person that Super304H steel adopts is: melting → hot rolling → punching → hot mastication process → cold drawing → solution treatment → finished product.Arrange (sofening treatment temperature 900 DEG C ~ 1000 DEG C, solid solution temperature 1050 DEG C ~ 1150 DEG C) with the processing parameter of traditional TP304H steel different, that Super304H steel adopts is T
softening> T
solid solutionthermal treatment mechanism, fix between 1250 DEG C ~ 1300 DEG C by hot mastication treatment temp, solid solution temperature fixed between 1050 ~ 1150 DEG C.Hot mastication process under this temperature condition can make the macrobead precipitated phase of high temperature hot rolling be solidly soluted in matrix, and follow-up solution treatment then makes M
23c
6keep the same seasonal part Nb (C of solid solution condition, N) disperse educt, Nb (the C separated out, N) motion of crystal boundary is hindered, ensure that more tiny austenite grain size, while the creep-rupture strength improving steel, make it have more superior high temperature oxidation resistance in steam energy.
Although compared with traditional material, Super304H steel tool in hot strength and high temperature resistance steam oxidation performance has great advantage, and usually has the rich niobium of bulk and separate out mutually in the Super304H steel wool pipe that melting, hot-puncturing process are formed.Under hot mastication technique improperly, the rich niobium of bulk is difficult to abundant dissolving mutually, and this is by the minimizing of Nb (C, N) disperse educt in the solution treatment that causes subsequently.Nb (C, the N) disperse educt reduced, by reducing the even fixed action of niobium to C free in matrix, causes M
23c
6the too much precipitation of phase, makes the Susceptibility To Intergranular Corrosion of Super304H greatly increase.Meanwhile, the complete processing of relative complex is difficult to ensure cooperatively interacting of precipitated phase, also can affect its corrosion among crystalline grains.At present, domesticly there occurs the superheater of a lot of Super304H steel and reheater tube because of intergranular corrosion and cause the accident of leakage or booster building extra-supercritical unit.
Due to the upper limit in Super304H steel up to 0.13% carbon content increased the weight of M
23c
6the possible degree of Intergranular precipitation, solves the susceptibility of prior art more by adopting the content reducing C to reduce its intergranular corrosion of Super304H intergranular corrosion.But this method is what to sacrifice the hot strength of Super304H steel be cost.
Summary of the invention
Problem to be solved by this invention, is just to provide a kind of method reducing the Susceptibility To Intergranular Corrosion of Super304 high temperature steel, and this method is by optimizing hot mastication technique, ensure that Nb (C in solution treatment, N) abundant precipitation, improves niobium in matrix and, to the fixed action of carbon, suppresses M
23c
6the precipitation of phase, thus the Susceptibility To Intergranular Corrosion reducing Super304H steel, reduce the leakage because intergranular corrosion causes or pipe explosion accident, improves the security of thermal power generation.
Solve the problems of the technologies described above, the technical solution used in the present invention is as follows:
Reduce a method for the Susceptibility To Intergranular Corrosion of Super304 high temperature steel, it is characterized in that comprising the following steps:
S1: one section of Super304H steel is carried out homogenizing solid solution pre-treatment in resistance-type heat treatment furnace and obtains pretreating specimen;
S2: S1 gained pretreating specimen is put into resistance-type heat treatment furnace and carries out sofening treatment, softening temperature is between 1250 DEG C ~ 1300 DEG C, carries out water-cooled, obtain softening sample after insulation 20min ~ 60min;
S3: S2 gained is softened sample carry out solution treatment in resistance-type heat treatment furnace, and carry out water-cooled, is softened+solid solution sample;
Described solid solution pre-treatment and solid solution treatment process are and heat 1150 DEG C × 30min in atmosphere, and then water-cooled is to room temperature.
This tests Super304H steel used is SUMITOMO CHEMICAL Metal Production, and virgin state is common supply of material state.
Principle of the present invention is: because the temperature range of various precipitated phase stable existence is different, adopt suitable hot mastication temperature and soaking time, the rich niobium of bulk can be made fully to dissolve mutually, to ensure Nb (C in follow-up solution treatment, N) abundant precipitation, play niobium in matrix and, to the fixed action of carbon, suppress M
23c
6the precipitation of phase, thus the Susceptibility To Intergranular Corrosion reducing Super304H steel.
Beneficial effect: the present invention is not when changing Super304H steel chemical composition, by optimizing hot mastication technique, rich for bulk in Super304H steel niobium is fully solidly soluted in austenitic matrix mutually, to ensure Nb (C in follow-up solution treatment, N) abundant precipitation, give full play to the fixed action of niobium to carbon, suppress M
23c
6the precipitation of phase, the precipitated phase state of Super304H steel is improved from the angle of optimization processing technology, thus under the prerequisite not reducing its hot strength, reduce the Susceptibility To Intergranular Corrosion of Super304H high temperature steel, so both improve the intergranular corrosion resistance performance of Super304H, can ensure again not reduce its hot strength, the leakage because intergranular corrosion causes or pipe explosion accident can be greatly reduced, improve the security of thermal power generation.
Accompanying drawing explanation
Fig. 1 is scanning electronic microscope (SEM) shape appearance figure of rich niobium phase in pre-solution treatment sample in embodiment 1 ~ 6;
Fig. 2 is the SEM shape appearance figure of rich niobium phase in softening sample in embodiment 5;
Fig. 3 is the DL-EPR curve of each embodiment sample after step (4) sensitized treatment in embodiment 1 ~ 6.
Embodiment
Below in conjunction with embodiment, the invention will be further described.
Embodiment 1:
S1: one section of Super304H steel is carried out homogenizing solid solution pre-treatment in resistance-type heat treatment furnace, concrete mode is in atmosphere with 1150 DEG C of heating 30min, and carries out water-cooled;
S2: the sample obtained according to S1 is put into resistance-type heat treatment furnace and carries out sofening treatment, concrete mode is with 1250 DEG C of heating 20min, and carries out water-cooled, obtains softening sample;
S3: the softening sample obtained according to S2 is carried out solution treatment in resistance-type heat treatment furnace, concrete mode is with 1150 DEG C of heating 30min, and carries out water-cooled, is softened+solid solution sample;
S4: by obtain according to S3 softening+solid solution sample puts into resistance-type heat treatment furnace and carries out sensitized treatment, concrete mode be heat 2h with 650 DEG C, and water-cooled, obtains sensitization sample;
S5: with the precipitation state of niobium phase rich in sem observation pre-solid solution state sample and softening sample, and the area percent recording rich niobium phase with quantitative metallography software is reduced to 0.21% from 0.25% of solid solution state; DL-EPR test is carried out to sensitization sample, records its intergranular corrosion susceptibility and be reduced to 0.95% from 1.33% of solid solution condition.
Embodiment 2:
S1: identical with embodiment 1;
S2: the sample obtained according to S1 is put into resistance-type heat treatment furnace and carries out sofening treatment, concrete mode is with 1250 DEG C of heating 45min, and carries out water-cooled, obtains softening sample;
S3: identical with embodiment 1;
S4: identical with embodiment 1;
S5: the precipitation state softening rich niobium phase in sample with sem observation, and the area percent recording rich niobium phase with quantitative metallography software is reduced to 0.19% from 0.25% of solid solution state; DL-EPR test is carried out to sensitization sample, records its intergranular corrosion susceptibility and be reduced to 0.91% from 1.33% of solid solution condition.
Embodiment 3:
S1: identical with embodiment 1;
S2: the sample obtained according to S1 is put into resistance-type heat treatment furnace and carries out sofening treatment, concrete mode is with 1250 DEG C of heating 60min, and carries out water-cooled, obtains softening sample;
S3: identical with embodiment 1;
S4: will be identical with embodiment 1;
S5: the precipitation state softening rich niobium phase in sample with sem observation, and the area percent recording rich niobium phase with quantitative metallography software is reduced to 0.18% from 0.25% of solid solution state; DL-EPR test is carried out to sensitization sample, records its intergranular corrosion susceptibility and be reduced to 0.80% from 1.33% of solid solution condition.
Embodiment 4:
S1: identical with embodiment 1;
S2: the sample obtained according to S1 is put into resistance-type heat treatment furnace and carries out sofening treatment, concrete mode is with 1300 DEG C of heating 20min, and carries out water-cooled, obtains softening sample;
S3: identical with embodiment 1;
S4: identical with embodiment 1;
S5: the precipitation state softening rich niobium phase in sample with sem observation, and the area percent recording rich niobium phase with quantitative metallography software is reduced to 0.15% from 0.25% of solid solution state; DL-EPR test is carried out to sensitization sample, records its intergranular corrosion susceptibility and be reduced to 0.34% from 1.33% of solid solution condition.
Embodiment 5:
S1: identical with embodiment 1;
S2: the sample obtained according to S1 is put into resistance-type heat treatment furnace and carries out sofening treatment, concrete mode is with 1300 DEG C of heating 45min, and carries out water-cooled, obtains softening sample;
S3: identical with embodiment 1;
S4: identical with embodiment 1;
S5: the precipitation state softening rich niobium phase in sample with sem observation, and the area percent recording rich niobium phase with quantitative metallography software is reduced to 0.09% from 0.25% of solid solution state; DL-EPR test is carried out to sensitization sample, records its intergranular corrosion susceptibility and be reduced to 0.27% from 1.33% of solid solution condition.
Embodiment 6:
S1: identical with embodiment 1;
S2: the sample obtained according to S1 is put into resistance-type heat treatment furnace and carries out sofening treatment, concrete mode is with 1300 DEG C of heating 60min, and carries out water-cooled, obtains softening sample;
S3: identical with embodiment 1;
S4: identical with embodiment 1;
S5: the precipitation state softening rich niobium phase in sample with sem observation, and the area percent recording rich niobium phase with quantitative metallography software is reduced to 0.08% from 0.25% of solid solution state; DL-EPR test is carried out to sensitization sample, records its intergranular corrosion susceptibility and be reduced to 0.26% from 1.33% of solid solution condition.
Table 1 is the metallographic quantitative result of rich niobium phase in each softening sample in embodiment 1 ~ 6 and the summary sheet of each sensitization sample intergranular corrosion susceptibility test result.
Table 1
From rich niobium phase quantitative result (table 1), along with the prolongation of hot mastication time, back dissolving is in Super304H steel matrix gradually mutually for rich niobium, and its amount of precipitation finally tends towards stability.From DL-EPR test result (Fig. 3), along with the prolongation of hot mastication time, intergranular corrosion susceptibility declines gradually, and variation tendency is consistent with the change of softening time with rich niobium phased soln amount.Under the identical softening time, improve hot mastication temperature, for the dissolving of rich niobium phase and the corrosion among crystalline grains of sensitization sample, there is active influence.
Above-described embodiment 5 is the present invention's preferably embodiment.
Shown by embodiment 1-6: by optimizing the hot mastication technique of Super304H steel, a rich niobium of bulk is fully dissolved mutually, ensures the abundant precipitation of Nb (C, N) in follow-up solution treatment, improve niobium in matrix and, to the fixed action of carbon, effectively can suppress M
23c
6the precipitation of phase, reduces the Susceptibility To Intergranular Corrosion of material.
Due to the prolongation along with softening temperature rising or soaking time, the oxidation of Super304H steel is also more and more serious, therefore under the prerequisite of close Susceptibility To Intergranular Corrosion, should select the softening process that softening temperature is lower or soaking time is shorter.Therefore, above-described embodiment 5 is the present invention's preferably embodiment.
Claims (2)
1. reduce a method for the Susceptibility To Intergranular Corrosion of Super304H high temperature steel, it is characterized in that comprising the following steps:
S1: one section of Super304H steel is carried out homogenizing solid solution pre-treatment in resistance-type heat treatment furnace and obtains pretreating specimen;
S2: S1 gained pretreating specimen is put into resistance-type heat treatment furnace and carries out sofening treatment, softening temperature is between 1250 DEG C ~ 1300 DEG C, carries out water-cooled, obtain softening sample after insulation 20min ~ 60min;
S3: S2 gained is softened sample carry out solution treatment in resistance-type heat treatment furnace, and carry out water-cooled, is softened+solid solution sample;
Described solid solution pre-treatment and solid solution treatment process are and heat 1150 DEG C × 30min in atmosphere, and then water-cooled is to room temperature.
2. the method for the Susceptibility To Intergranular Corrosion of reduction Super304H high temperature steel according to claim 1, is characterized in that: the softening temperature of described step S2 is 1300 DEG C, insulation 45min; The sensitized treatment of described step S4 is with 650 DEG C of heating 2h.
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| CN201410782833.8A CN104451074A (en) | 2014-12-15 | 2014-12-15 | Method for lowering intercrystalline corrosion susceptibility of Super304H heat-resistant steel |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110195152A (en) * | 2019-06-11 | 2019-09-03 | 河南神州精工制造股份有限公司 | A method of improving austenitic stainless steel anti intercrystalline corrosion ability |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58167726A (en) * | 1982-03-29 | 1983-10-04 | Sumitomo Metal Ind Ltd | Method of preparing austenitic stainless steel |
| JPS6156234A (en) * | 1984-08-23 | 1986-03-20 | Sumitomo Metal Ind Ltd | Manufacture of austenite stainless fine grain steel |
| CN101117689A (en) * | 2007-08-20 | 2008-02-06 | 江阴市江东不锈钢制造有限公司 | 03Cr22Ni4NbN austenite-ferritic stainless steel and production technology therefor |
-
2014
- 2014-12-15 CN CN201410782833.8A patent/CN104451074A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58167726A (en) * | 1982-03-29 | 1983-10-04 | Sumitomo Metal Ind Ltd | Method of preparing austenitic stainless steel |
| JPS6156234A (en) * | 1984-08-23 | 1986-03-20 | Sumitomo Metal Ind Ltd | Manufacture of austenite stainless fine grain steel |
| CN101117689A (en) * | 2007-08-20 | 2008-02-06 | 江阴市江东不锈钢制造有限公司 | 03Cr22Ni4NbN austenite-ferritic stainless steel and production technology therefor |
Non-Patent Citations (1)
| Title |
|---|
| 熊夏华: "新型锅炉耐热不锈钢Super304H的抗晶间腐蚀性能研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅰ辑》, no. 01, 15 January 2014 (2014-01-15) * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110195152A (en) * | 2019-06-11 | 2019-09-03 | 河南神州精工制造股份有限公司 | A method of improving austenitic stainless steel anti intercrystalline corrosion ability |
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Application publication date: 20150325 |