CN102121886A - Experimental method for detecting hot-charging brittleness of steel - Google Patents
Experimental method for detecting hot-charging brittleness of steel Download PDFInfo
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- CN102121886A CN102121886A CN2010105994725A CN201010599472A CN102121886A CN 102121886 A CN102121886 A CN 102121886A CN 2010105994725 A CN2010105994725 A CN 2010105994725A CN 201010599472 A CN201010599472 A CN 201010599472A CN 102121886 A CN102121886 A CN 102121886A
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Abstract
The invention relates to an experimental method for detecting the hot-charging brittleness of steel, and belongs to the technical field of technological property detection of steel in iron and steel metallurgy. The experimental method comprises the following steps: (1) cutting a casting blank or rolled metal of the steel grade to be detected into a sample; (2) vacuumizing an operating room and introducing argon for protection before experiment so as to prevent oxidation of the sample; (3) carrying out a stretching experiment in a thermal simulation testing machine, wherein, the austenitizing temperature, warming and cooling speed and stretching temperature parameters in the experiment change along with different components in the steel grade to be detected; and (4) after the sample is fractured, measuring the area of a fracture position so as to calculate the shrinkage rate of the fracture surface, and taking the shrinkage rate as a high-temperature plasticity index to determine whether the detected steel has the hot-charging brittleness. The experimental method has the beneficial effects of simplicity and convenience in operation, short time and low requirements on vacuum degree; and by utilizing the method, the hot-charging brittleness of the material can be reflected without exaggeration, whether the steel has the hot-charging brittleness can be accurately determined, and the hot-charging brittleness temperature range of the steel can be determined.
Description
Technical field:
The present invention relates to a kind of experimental technique that detects steel hot charging fragility, belong to steel shop characteristic detection technique field in the Ferrous Metallurgy.
Background technology:
In--hot charging--rolling production, crack defect often appears in finished surface at continuous casting, and this defective is accompanied by strand and produces in certain temperature range shove charge, and this phenomenon occurs over just among the steel grade of some special component.When steel have " hot charging fragility ", above-mentioned " hot charging cracking " phenomenon can take place, therefore, whether the check steel have hot charging fragility, are to judge that steel can be denied the prerequisite of hot charging cracking.At present, detect the experimental technique of steel " hot charging fragility ", perhaps there be " hot charging embrittlement degree is lighter " (the lowest surfaces shrinkage is 61%) that records, can not fully reflect the problem of hot charging embrittlement effect, perhaps have " experimental period is long " (needing 50 minutes approximately), and problems such as " requirement have higher vacuum tightness " around the sample, if vacuum tightness is low, experimental period is long in addition, then can cause sample top layer oxidation crust, pin down thermopair and move, influence experimental result with constriction.
Summary of the invention:
The object of the invention provides a kind of experimental technique that detects steel hot charging fragility, solve the problem of " the embrittlement degree is lighter ", " experimental period is long " and " vacuum tightness is had relatively high expectations " in the background technology, whether have hot charging fragility by the check steel, judge that steel can be denied the hot charging cracking.
Technical scheme of the present invention is:
A kind of experimental technique that detects steel hot charging fragility, concrete steps are: 1. steel grade strand to be measured or stocking cut are become sample; 2. operation room vacuumizes and the applying argon gas protection before the experiment, prevents the sample oxidation; 3. carry out stretching experiment on thermodynamic simulated experiment machine, the austenitizing temperature in the test method, intensification cooling rate, draft temperature parameter change with the composition of tested steel grade is different; 4. after sample is broken, measure the incision position area,, determine whether the check steel have hot charging fragility as the high-temp plastic index to calculate reduction of area.
Heat simulating tester is to utilize small sample, carry out the important means of metallurgical material research, in new product development and process optimization, play an important role, the major function of thermodynamic simulated experiment machine is to reproduce material (particularly ferrous materials) being heated in preparation or hot procedure, or is heated simultaneously and stressed physical process.
Said heat simulating type of heating is the resistance heat heating.
Austenitizing temperature in the test method of the present invention, intensification cooling rate, draft temperature parameter change with the composition of tested steel grade is different.
The concrete experiment parameter of inventive method is as follows:
(1) austenitizing is handled
Heating process: programming rate is different and different according to the height of temperature, below 1200 ℃, and programming rate V1=5--20 ℃/s; 1200--1350 ℃, programming rate V2=3--5 ℃/s; 1350--1420 ℃, programming rate V3=0.5--1 ℃/s, programming rate raises with heating-up temperature and reduces gradually is in order to prevent that temperature from leaping high the sample fusing;
Austenitizing temperature and isothermal time: austenitizing temperature T1 is 1200--1420 ℃, isothermal time t1 is 15--500s, the two cooperation can be controlled the dissolution degree of precipitates such as MnS or AlN effectively, this influence for hot charging fragility is very big, therefore, should properly be selected, and can not be adopted single heating cycle according to the difference of S in the steel or Al content;
(2) cooling behind the austenitizing and temperature-rise period
The present invention simulates the hot charging process, temperature-fall period by the process of cooling and intensification: the cooling velocity V4 of temperature-fall period is 0.1--20 ℃/s, and this value is very significant to the influence of hot charging fragility; Hot charging transition temperature R is 25--1100 ℃, can determine hot charging brittle temperature interval by changing this value; Temperature-rise period: programming rate V5 is 0.1--15 ℃/s, and this value is very significant to the influence of hot charging fragility equally;
(3) draft temperature and tensile strain rate
Draft temperature T2 is 900--1100 ℃, and tensile strain rate is 0.05--0.0005s-1, till sample is broken.
Beneficial effect of the present invention: the hot charging fragility that can fully demonstrate material, easy and simple to handle, weak point consuming time, require low to vacuum tightness, the inventive method can fully reflect the hot charging fragility of material, again can it is not exaggerative, it can be measured steel exactly and whether have hot charging fragility (promptly whether having V font hot charging embrittlement groove), and can determine the hot charging brittle temperature interval of steel.
Description of drawings:
Fig. 1 is the stretching experiment synoptic diagram;
Fig. 2 detects the experimental technique curve of steel hot charging fragility for the present invention
Among the figure:
V1: room temperature to 1200 ℃ firing rate, 5--20 ℃/s
V2:1200--1350 ℃ of firing rate, 3--5 ℃/s
V3:1350--1420 ℃ of firing rate, 0.5--1 ℃/s
V4: the cooling rate behind the austenitizing, 0.1--20 ℃/s
V5: programming rate behind the hot charging, 0.1--15 ℃/s
T1: austenitizing temperature, 1200--1420 ℃
T2: draft temperature, 900--1100 ℃
T1: austenitizing isothermal time, 15--500s
R: hot charging transition temperature, 25--1100 ℃;
" the sample 1 hot charging plasticity curve that acid-soluble aluminum content is higher " that Fig. 3 records for embodiment one;
" the sample 2 hot charging plasticity curves " that Fig. 4 records for embodiment two;
" the sample 3 hot charging plasticity curves " that Fig. 5 records for embodiment three.
Embodiment:
The invention will be further described by the following examples.
With reference to accompanying drawing 1; 2; in an embodiment; steel grade strand to be measured or stocking cut are become the sample of Φ 10 * 120mm; the standard thread of each belt length 15mm of two ends; in Gleeble(commodity brand) carry out stretching experiment on the thermodynamic simulated experiment machine; operation room vacuumizes and the applying argon gas protection before the experiment; prevent the sample oxidation; type of heating is the resistance heat heating; austenitizing temperature in the test method; the intensification cooling rate; the draft temperature parameter changes with the composition of tested steel grade is different; after sample is broken, measure the incision position area to calculate reduction of area, as the high-temp plastic index.
Embodiment one, with reference to accompanying drawing 3.
The chemical constitution of sample is C:0.06%, Mn:0.16%, Si:0.029%, Als:0.080%, P:0.011%, S:0.005%.
In the experiment, the parameter of setting the invention experimental technique is as follows: firing rate V1=10--15 ℃/s, and V2=3--5 ℃/s, V3=0.5--1 ℃/s; Austenitizing temperature T1=1300--1420 ℃; Austenitizing isothermal time t1=15--200s; Cooling rate V4=1--15 behind the austenitizing ℃/s; Programming rate V5=0.1--10 ℃/s behind the hot charging; Draft temperature T2=900--1100 ℃; Tensile strain rate is 0.05--0.0005s-1, till sample is broken; Change hot charging transition temperature R, scope is 25--1100 ℃, determines the reduction of area of fracture surface of sample under the different hot charging transition temperatures, makes the hot charging transition temperature--reduction of area corresponding relation curve.
The acid-soluble aluminum content higher sample 1 hot charging plasticity curve of Fig. 3 for adopting foregoing invention experimental technique and background technology experimental technique to record respectively.As can be seen, the hot charging plasticity index that adopts the background technology method to record is very high, and reduction of area is all greater than 91%, and plasticity is fine, does not find hot charging embrittlement phenomenon; And the hot charging plasticity curve that adopts inventive method to record, visible significantly hot charging embrittlement district, the brittle temperature interval is 600--900 ℃, the lowest surfaces shrinkage only is 28%, occurs in 750 ℃.The fully hot charging embrittlement tendency of display material of inventive method is described.
Embodiment two, with reference to accompanying drawing 4
The chemical constitution of sample is C:0.18%, Mn:1.37%, Si:0.4%, Als:0.001%, P:0.027%, S:0.022%.
Present embodiment adopts invention experimental technique and the background technology experimental technique identical with embodiment one, has measured the hot charging plasticity curve of sample respectively, sees Fig. 4.As can be seen, there is hot charging embrittlement district in the sample hot charging plasticity curve that adopts the background technology method to record, but the embrittlement degree wants light than what inventive method recorded, and the fully hot charging embrittlement tendency of display material of inventive method is described equally.
Embodiment three, with reference to accompanying drawing 5
The chemical constitution of sample is C:0.2%, Mn:0.26%, Si:0.07%, Als:0.017%, P:0.014%, S:0.006%.
Present embodiment is same to adopt invention experimental technique and the background technology experimental technique identical with embodiment one, has measured the hot charging plasticity curve of sample 3 respectively, sees Fig. 5.As can be seen from the figure, sample 3 reduction of area that employing background technology method records are all greater than 92%, and plasticity is fine; Though the reduction of area that adopts inventive method to record is 84% at 650 ℃ and 700 ℃, has shown embrittlement in a way, the embrittlement degree is extremely light, and can think does not have hot charging fragility.Illustrate that inventive method can not exaggerate the hot charging embrittlement tendency of steel.
In sum: inventive method can fully reflect the hot charging fragility of material, again can it is not exaggerative.It can be measured steel exactly and whether have hot charging fragility (promptly whether having V font hot charging embrittlement groove), and can determine the hot charging brittle temperature interval of steel.
Claims (4)
1. an experimental technique that detects steel hot charging fragility is characterized in that, the body step is: 1. steel grade strand to be measured or stocking cut are become sample; 2. operation room vacuumizes and the applying argon gas protection before the experiment, prevents the sample oxidation; 3. carry out stretching experiment on thermodynamic simulated experiment machine, the austenitizing temperature in the test method, intensification cooling rate, draft temperature parameter change with the composition of tested steel grade is different; 4. after sample is broken, measure the incision position area,, determine whether the check steel have hot charging fragility as the high-temp plastic index to calculate reduction of area.
2. according to the experimental technique of the described detection steel hot charging fragility of claim 1, it is characterized in that the heat simulating type of heating of saying is the resistance heat heating.
3. according to the experimental technique of claim 1 or 2 described detection steel hot charging fragility, it is characterized in that the body experiment parameter is as follows:
(1) austenitizing is handled
Heating process: programming rate is different and different according to the height of temperature, below 1200 ℃, and programming rate V1=5--20 ℃/s; 1200--1350 ℃, programming rate V2=3--5 ℃/s; 1350--1420 ℃, programming rate V3=0.5--1 ℃/s, programming rate raises with heating-up temperature and reduces gradually is in order to prevent that temperature from leaping high the sample fusing;
Austenitizing temperature and isothermal time: austenitizing temperature T1 is 1200--1420 ℃, isothermal time t1 is 15--500s, the two cooperation can be controlled the dissolution degree of precipitates such as MnS or AlN effectively, this influence for hot charging fragility is very big, therefore, should properly be selected according to the difference of S in the steel or Al content;
(2) cooling behind the austenitizing and temperature-rise period
Temperature-fall period: the cooling velocity V4 of temperature-fall period is 0.1--20 ℃/s, and this value is very significant to the influence of hot charging fragility; Hot charging transition temperature R is 25--1100 ℃, can determine hot charging brittle temperature interval by changing this value; Temperature-rise period: programming rate V5 is 0.1--15 ℃/s, and this value is very significant to the influence of hot charging fragility equally;
(3) draft temperature and tensile strain rate
Draft temperature T2 is 900--1100 ℃, and tensile strain rate is 0.05--0.0005s-1, till sample is broken.
4. according to the experimental technique of the described detection steel hot charging fragility of claim 1, it is characterized in that, that says becomes sample with steel grade strand to be measured or stocking cut, concrete steps are the samples that steel grade strand to be measured or stocking cut become Φ 10 * 120mm, the standard thread of each belt length 15mm of two ends.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105158083A (en) * | 2015-09-06 | 2015-12-16 | 北京科技大学 | Test method for combining strength in combining process of dissimilar materials |
| CN108398336A (en) * | 2017-02-05 | 2018-08-14 | 鞍钢股份有限公司 | A method of obtaining drawing by high temperature fracture surface of sample |
| CN112834339A (en) * | 2020-12-31 | 2021-05-25 | 东北大学 | Method for measuring critical strain of corner crack propagation of continuous casting billet |
| CN117110031A (en) * | 2023-10-24 | 2023-11-24 | 江苏省沙钢钢铁研究院有限公司 | Clamp and method for testing high-temperature tensile strength of thin strip sample |
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| CN1041823A (en) * | 1989-11-20 | 1990-05-02 | 机械电子工业部北京机电研究所 | The prefabricating fatigue crack on fragile materials method and apparatus |
| CN2911655Y (en) * | 2006-04-28 | 2007-06-13 | 北京科技大学 | Stretching test clamp for brittle non-standard sample |
| CN101178343A (en) * | 2007-11-30 | 2008-05-14 | 山东大学 | Brittle material test member felted axis pulling experiment positioning apparatus |
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2010
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Patent Citations (4)
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| JPS61212743A (en) * | 1985-03-18 | 1986-09-20 | Sumitomo Metal Ind Ltd | Steel pipe test |
| CN1041823A (en) * | 1989-11-20 | 1990-05-02 | 机械电子工业部北京机电研究所 | The prefabricating fatigue crack on fragile materials method and apparatus |
| CN2911655Y (en) * | 2006-04-28 | 2007-06-13 | 北京科技大学 | Stretching test clamp for brittle non-standard sample |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105158083A (en) * | 2015-09-06 | 2015-12-16 | 北京科技大学 | Test method for combining strength in combining process of dissimilar materials |
| CN105158083B (en) * | 2015-09-06 | 2019-01-29 | 北京科技大学 | The test method of bond strength in a kind of dissimilar material cohesive process |
| CN108398336A (en) * | 2017-02-05 | 2018-08-14 | 鞍钢股份有限公司 | A method of obtaining drawing by high temperature fracture surface of sample |
| CN108398336B (en) * | 2017-02-05 | 2020-10-27 | 鞍钢股份有限公司 | Method for obtaining fracture of high-temperature tensile sample |
| CN112834339A (en) * | 2020-12-31 | 2021-05-25 | 东北大学 | Method for measuring critical strain of corner crack propagation of continuous casting billet |
| CN117110031A (en) * | 2023-10-24 | 2023-11-24 | 江苏省沙钢钢铁研究院有限公司 | Clamp and method for testing high-temperature tensile strength of thin strip sample |
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Address after: 063016 Binhe Road, Hebei, Tangshan City, No. 9 Patentee after: River steel Limited by Share Ltd Tangshan branch Address before: 063016 Binhe Road, Hebei, Tangshan City, No. 9 Patentee before: Hebei Steel Co., Ltd., Tangshan Branch |