CN102854211A - Method for measuring dissolving temperature of Nb (C,N) in low-carbon micro-alloyed steel by internal friction method - Google Patents
Method for measuring dissolving temperature of Nb (C,N) in low-carbon micro-alloyed steel by internal friction method Download PDFInfo
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Abstract
The invention provides a method for measuring dissolving temperature of Nb (C,N) in low-carbon micro-alloyed steel. According to the method, the content of niobium in low-carbon micro-alloyed steel components exceeds 0.01 percent, and the C content is smaller than 0.2 percent. The method comprises the following steps of: performing solution treatment on a sample which is fully separated out through Nb (C,N); tempering the sample subjected to the solution treatment at 350 DEG C higher than the SKK peak occurrence temperature for 60 to 70 minutes; measuring the sample through the internal friction method, so as to obtain the strength and temperature changing curve of the material SKK internal friction peak; and determining the dissolving temperature of Nb (C,N). The method is high in testing precision and has high applicability on the Nb-containing low-carbon micro-alloyed steel with different components.
Description
Technical field
The invention belongs to the material metallurgical technology field, specifically a kind of By Internal Friction Measurements is measured the detection method of Nb (C, N) solution temperature in the low-carbon micro steel-alloy.
Background technology
Microalloy element Nb is one of topmost alloying element of the modern super-steel of development, main manifestations is for suppressing austenitic Deformation recrystallization and stoping grain growth in course of hot rolling, carboritride Nb (C by niobium, N) strain inducing is separated out, and steel is carried out refined crystalline strengthening and precipitation strength.Because usually existing a large amount of Nb (C in such steel casting process, N) separate out, therefore, that the selection of hot rolling heating-up temperature at first needs to consider is Nb (C, N) solution temperature, for heating-up temperature and the technique of formulating in the rational hot rolling production run provides theoretical foundation, impel the front complete solid solution of Nb element of hot rolling deformation in austenite.
Before the present invention, Nb (C in the micro alloyed steel, N) solution temperature detects the method that adopts generally TEM microscopic inspection and calculation of thermodynamics, kind is difficult to quantitative accurately before these two kinds of methods, the latter is owing to only considered the thermodynamic data of perfect condition, for industrial actual production slab, there are certain deviation in result of calculation and real data.Recently, Chinese patent CN201010017958 discloses a kind of resistivity and has detected Nb (C in the low-carbon micro steel-alloy, N) method of solution temperature, but its principle Main Basis Nb (C, N) refining effect of crystallite dimension is caused the change of resistivity, therefore patent restriction microalloy steel grade Nb content need reach 0.03 %, and the addition of microalloy steel grade Nb often is lower than this value.
In-fighting is a kind of physical property of material, different defect type in the metal material, and Defect configuration can show abundant Internal Friction Phenomena.The athletic meeting of defective causes in-fighting, and conversely, the analysis of Internal Friction Phenomena can provide again the relevant information about fault in material, obtains about relevant informations such as defect kind, configuration, density, thermodynamic processes.Existing a few patents discloses the improvement technology of ferrous materials in-fighting measuring method and device, but it is still rare that the in-fighting technology is directly applied to the domestic patented technology of metal material research.The Internal Friction Peak that ferrous materials occurs in heating process is mainly Snoek (SK) peak and Snoek-Koster-Ke (SKK) peak.Wherein the general temperature that occurs in SK peak is because bcc metal intermediate gap atom spreads the in-fighting that causes, thereby can indirectly characterizes material behavior relevant with the solid solution capacity of the interstitial atoms such as C, N in the ferrous materials about 20 ~ 70 ℃.Another important in-fighting source is dislocation in the ferrous materials, the position that the SKK peak occurs is generally about 180 ~ 250 ℃, the reason of its generation is the Internal Friction Peak that dislocation pulls the reciprocation generation of solute atoms, and the factor that causes the ferrous materials Dislocations resistance of motion to change all will make the feature at SKK peak change.In low-carbon micro steel-alloy, just separating out of minute quantity nanoscale Nb (C, N) second phase particles can be played significant pinning effect to dislocation.Therefore, Nb (C, N) separate out and the solid solution content of Nb will make the power of SKK Internal Friction Peak occur changing thereupon.The intensity Nb (C, N) at SKK peak separates out and increases and weaken, and Nb will reduce the pinning effect to dislocation when existing with the solid solution attitude, and the SKK peak intensity increases, thereby provides criterion for in-fighting technology judgement Nb (C, N) solution temperature.
Summary of the invention
The purpose of this invention is to provide a kind of By Internal Friction Measurements and measure Nb (C in the low-carbon micro steel-alloy, N) method of solution temperature, the method adopts Nb (C, N) precipitated phase solution temperature in in-fighting technology, the Accurate Determining low-carbon micro steel-alloy by suitable front Technology for Heating Processing.
The objective of the invention is to be achieved through the following technical solutions:
A kind of By Internal Friction Measurements is measured Nb (C in the low-carbon micro steel-alloy, N) method of solution temperature, it is characterized in that: the method is carried out in advance thermal treatment to low-carbon micro steel-alloy, by measuring Nb (C, N) variation of second-phase SKK Internal Friction Peak intensity that the dislocation pinning effect is caused, determine the solution temperature of Nb (C, N); Concrete steps are as follows:
1) content of niobium is lower than 0.2% above 0.01%, C content in the low-carbon micro steel-alloy alloying component;
2) will be through Nb (C, the sample of N) fully separating out is incubated between 900～1260 ℃, and the interval uniform temp is chosen a temperature test point, sample cools off in water rapidly after all being incubated 60-70 minute under each probe temperature, make more than Nb (C, N) solution temperature that Nb (C, N) precipitated phase fully dissolves in the sample of heating, avoid the Nb element of solid solution again to separate out with the form of Nb (C, N);
3) sample after solution treatment 350 ℃ of temperature occurred and carries out tempering in 60-70 minute being higher than the SKK peak, eliminate the inherent vice of the fast cold tissue of material, make alloying element carbon before in-fighting test, fully separate out in advance transformation, reduce the C element and carry out in the in-fighting test heating process impact on the SKK peak in 300 ℃ of following temperature subsequently;
4) adopt By Internal Friction Measurements that the sample after above-mentioned Technology for Heating Processing is measured, obtain intensity and the temperature variation curve of material SKK Internal Friction Peak, the solution temperature of determining Nb (C, N) according to intensity and the temperature variation curve of material SKK Internal Friction Peak.
Among the present invention, because the nanoscale Nb (C of minute quantity, N) precipitated phase will form strong reciprocation with dislocation motion, so the content for niobium element in the microalloyed steel containing Nb gets final product above 0.01%, but because the C element also is on the larger element of in-fighting value impact, so not only taked corresponding thermal treatment measure to alleviate the impact of C element, and only be lower than 0.2% low-carbon micro steel-alloy for C content.
Will be through sample quench cooled after being incubated same time for a long time between 900～1260 ℃ that Nb (C, N) fully separates out.Its objective is that Nb (C, N) precipitated phase can fully dissolve in the sample that makes heating more than Nb (C, N) solution temperature, then the quick cooling of sample quenching is again to separate out with the form of Nb (C, N) for fear of the Nb element of solid solution.Can between 900～1260 ℃, choose a temperature test point every 25 ℃; Sample cools off in water rapidly after all being incubated 60 minutes under each probe temperature.
Since the solid solution of interstitial atom C with separate out also and can play material impact to the SKK peak that the motion of low-carbon micro steel-alloy Dislocations causes, consider that it is about 180 ~ 250 ℃ that temperature range generally appears in the SKK peak, the sample after solution treatment 350 ℃ of temperature occurred and carries out long-time tempering being higher than the SKK peak.Its purpose is in order to eliminate the inherent vice of the fast cold tissue of material on the one hand, on the other hand because the solid solution of Nb and separate out transformation and substantially do not changing below 350 ℃, therefore this subsequent heat treatment method can make alloying element carbon fully separate out in advance transformation before the in-fighting test, carries out in the in-fighting test heating process impact on the SKK peak thereby reduce the C element in 300 ℃ of following temperature subsequently.
Adopt the in-fighting technology that the sample after above-mentioned Technology for Heating Processing is measured, according to the intensity of material SKK Internal Friction Peak and the solution temperature of temperature variation curve judgement Nb (C, N).
The present invention has the following advantages and effect:
The invention provides the measuring method of Nb (C, N) solution temperature in a kind of low-carbon (LC) microalloyed steel containing Nb, for such plate slab hot rolling produce in the formulation of heating process the production foundation is provided.Because the in-fighting technology is responsive to the reaction of material internal defect, this assay method not only measuring accuracy is higher, and it is stronger that heterogeneity is contained Nb low-carbon micro steel-alloy applicability, compare with in the past tem observation, resistivity measurement, the content that can measure niobium element in the microalloyed steel containing Nb is lower, only need surpass 0.01% and get final product.
Description of drawings
The SKK peak intensity of Fig. 1 embodiment 1 changes and Nb (C, N) solution temperature graph of a relation.
Embodiment
Surpass 0.01% for content of niobium, C content is lower than 0.2% low-carbon micro steel-alloy, at first one group of test sample is carried out 900 ~ 1200 ℃ of high annealing thermal treatments, sample is chosen a temperature test point according to the needs of temperature measurement accuracy every 5 ~ 25 ℃ and is carried out Quenching Treatment between 900～1260 ℃ subsequently, heat treating equipment adopts high precision tubular type resistance-heated furnace to carry out, measuring error ± 3 ℃.Then sample carries out temper at 350 ℃.
Sample after adopting at last in-fighting equipment to thermal treatment carries out in-fighting to be measured, and draws the relation curve between SKK Internal Friction Peak intensity and the temperature variation.
Embodiment 1
1) embodiment composition
Embodiment 1 is the concrete composition of low-carbon micro steel-alloy Q890, sees Table 1.
Table 1 embodiment 1 chemical constitution (wt. %)
| C | Si | Mn | P | S | Cr | Mo | Ni | V | N | Nb |
| 0.15 | 0.36 | 1.2 | 0.006 | 0.002 | 0.8 | 0.5 | 1.1 | 0.07 | 0.004 | 0.015 |
2) solid solution treatment process of Nb (C, N) solution temperature mensuration
The low-carbon microalloy hot rolled plate sampling that Nb (C, N) fully separates out is chosen a temperature test point every 25 ℃ afterwards between 900～1260 ℃.Sample cools off in water rapidly after all being incubated 60 minutes under each probe temperature.
3) remove the subsequent heat treatment that interstitial atom C affects
Sample after quenching between 900～1260 ℃ takes out after 60 minutes through 350 ℃ of temper again.
4) measurement of in-fighting
Sample after adopting the multi-functional Internal Friction Meter of MFP-1000 to thermal treatment carries out in-fighting to be measured, according to the intensity of material SKK Internal Friction Peak in the test acquired results and the solution temperature of temperature variation curve judgement Nb (C, N).
Embodiment 1 final acquisition sample SKK peak intensity value varies with temperature and the results are shown in Figure 1, can find out that sample in-fighting Strength Changes curve turnover occurs at 1140 ℃.Be lower than 1140 ℃ of heating, material SKK peak in-fighting value is higher than 1140 ℃ of heating along with the rising of temperature increases slowly, and the SKK peak in-fighting value of material increases sharply.This is that the Nb (C, N) that fully separates out not yet begins dissolving owing to be lower than 1140 ℃ of heating, still exists with the form of second phase particles and dislocation is played pinning effect, and the resistance of motion of dislocation is larger, and in-fighting intensity is relatively low.Be higher than 1140 ℃ of heating, Nb (C, the N) second-phase of fully separating out through thermal pretreatment in the material dissolves gradually, and the Nb element is present in the ferrous materials with the form of solid solution in quenching process subsequently.Therefore, the content of Nb (C, N) reduces rapidly, and precipitated phase and interaction of dislocation alleviate, and the SKK peak in-fighting value of material increases rapidly.In temperature heating more than 1200 ℃, the variation of SKK peak in-fighting value eases up again gradually, this is that Nb (C, N) dissolves fully in the material owing to be higher than 1200 ℃ of heating, therefore judge that 1140 ℃ are this alloy Nb (C, N) dissolving initial temperature, and 1200 ℃ be Nb (C, N) dissolving finishing temperature, thereby point out that this slab hot rolling production heating-up temperature is because reaching the abundant dissolving of guarantee Nb (C, N) more than 1200 ℃.
Claims (2)
1. a By Internal Friction Measurements is measured Nb (C in the low-carbon micro steel-alloy, N) method of solution temperature, it is characterized in that: the method is carried out in advance thermal treatment to low-carbon micro steel-alloy, by measuring Nb (C, N) variation of second-phase SKK Internal Friction Peak intensity that the dislocation pinning effect is caused, determine the solution temperature of Nb (C, N); Concrete steps are as follows:
1) content of niobium is lower than 0.2% above 0.01%, C content in the low-carbon micro steel-alloy alloying component;
2) will be through Nb (C, the sample of N) fully separating out is incubated between 900～1260 ℃, and the interval uniform temp is chosen a temperature test point, sample cools off in water rapidly after all being incubated 60-70 minute under each probe temperature, make more than Nb (C, N) solution temperature that Nb (C, N) precipitated phase fully dissolves in the sample of heating, avoid the Nb element of solid solution again to separate out with the form of Nb (C, N);
3) sample after solution treatment 350 ℃ of temperature occurred and carries out tempering in 60-70 minute being higher than the SKK peak, eliminate the inherent vice of the fast cold tissue of material, make alloying element carbon before in-fighting test, fully separate out in advance transformation, reduce the C element and carry out in the in-fighting test heating process impact on the SKK peak in 300 ℃ of following temperature subsequently;
4) adopt By Internal Friction Measurements that the sample after above-mentioned Technology for Heating Processing is measured, obtain intensity and the temperature variation curve of material SKK Internal Friction Peak, the solution temperature of determining Nb (C, N) according to intensity and the temperature variation curve of material SKK Internal Friction Peak.
2. By Internal Friction Measurements according to claim 1 is measured the method for Nb (C, N) solution temperature in the low-carbon micro steel-alloy, it is characterized in that: choose a temperature test point every 25 ℃ between 900～1260 ℃; Sample cools off in water rapidly after all being incubated 60 minutes under each probe temperature.
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Cited By (6)
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| CN103969284A (en) * | 2014-04-24 | 2014-08-06 | 南京钢铁股份有限公司 | Thermal expansion method for measuring temperature enabling carbon in low-carbon steel to be completely dissolved in austenite |
| CN104007244A (en) * | 2014-05-06 | 2014-08-27 | 南京钢铁股份有限公司 | Method for determination of Fe3C solubility and precipitation amount of low-carbon microalloyed steel material |
| CN107490665A (en) * | 2016-06-11 | 2017-12-19 | 上海梅山钢铁股份有限公司 | Fe in cold rolling low carbon aluminum-killed steel plate tissue3The detection method of C amount of precipitations |
| CN108254442A (en) * | 2018-01-01 | 2018-07-06 | 首钢集团有限公司 | The method that nitrogen exists and is distributed is dissolved in a kind of judgement steel |
| CN109979707A (en) * | 2019-03-29 | 2019-07-05 | 武汉理工大学 | A kind of method of Electromagnetic Treatment debugging metal works hardness distribution |
| CN110031599A (en) * | 2019-03-07 | 2019-07-19 | 上海大学 | The method of Snoek relaxation internal friction peak measurement interstitial carbon content is utilized in material α-Fe system |
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| CN103969284A (en) * | 2014-04-24 | 2014-08-06 | 南京钢铁股份有限公司 | Thermal expansion method for measuring temperature enabling carbon in low-carbon steel to be completely dissolved in austenite |
| CN104007244A (en) * | 2014-05-06 | 2014-08-27 | 南京钢铁股份有限公司 | Method for determination of Fe3C solubility and precipitation amount of low-carbon microalloyed steel material |
| CN104007244B (en) * | 2014-05-06 | 2015-10-28 | 南京钢铁股份有限公司 | Measure Fe in low-carbon microalloy Steel material 3the method of C meltage and amount of precipitation |
| CN107490665A (en) * | 2016-06-11 | 2017-12-19 | 上海梅山钢铁股份有限公司 | Fe in cold rolling low carbon aluminum-killed steel plate tissue3The detection method of C amount of precipitations |
| CN108254442A (en) * | 2018-01-01 | 2018-07-06 | 首钢集团有限公司 | The method that nitrogen exists and is distributed is dissolved in a kind of judgement steel |
| CN110031599A (en) * | 2019-03-07 | 2019-07-19 | 上海大学 | The method of Snoek relaxation internal friction peak measurement interstitial carbon content is utilized in material α-Fe system |
| CN110031599B (en) * | 2019-03-07 | 2021-11-05 | 上海大学 | Method for measuring interstitial carbon atom content by utilizing Snoek relaxation internal consumption peak in material alpha-Fe system |
| CN109979707A (en) * | 2019-03-29 | 2019-07-05 | 武汉理工大学 | A kind of method of Electromagnetic Treatment debugging metal works hardness distribution |
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