CN104988299A - Control method for avoiding large-thickness medium-and-high carbon steel cutting delayed cracks in winter - Google Patents
Control method for avoiding large-thickness medium-and-high carbon steel cutting delayed cracks in winter Download PDFInfo
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- CN104988299A CN104988299A CN201510453518.5A CN201510453518A CN104988299A CN 104988299 A CN104988299 A CN 104988299A CN 201510453518 A CN201510453518 A CN 201510453518A CN 104988299 A CN104988299 A CN 104988299A
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Abstract
The invention discloses a control method for avoiding large-thickness medium-and-high carbon steel cutting delayed cracks in winter. A high carbon steel plate is slowly cooled after normalizing treatment and flame cutting are carried out; in the high carbon steel plate, the content of C ranges from 0.45wt% to 0.47wt%, and the content of Mn ranges from 0.70 wt% to 0.85wt%; and in the normalizing treatment process, the normalizing temperature ranges from 850 DEG C to 880 DEG C, and the heat preservation time ranges from 1.5 min/mm to 2.5 min/mm. According to the method, the design of the high C content and the high Mn content is adopted, so that the martensitic structure is effectively reduced, the stress concentration caused by the heat treatment is reduced, and generation of the delayed cracks is effectively avoided. According to the method, when flame cutting is carried out, temperature waiting cutting is adopted, wind-avoiding cutting is carried out so as to decrease the cooling speed of a cutting face after the steel plate is cut, and the cut steel plate enters a slow cooling pit in time for stress treatment; generation of the martensitic structure is reduced more efficiently, the structure stress concentration is reduced, and the stress delayed cracks caused after flame cutting are avoided; and the outer-plane rate of the delayed cracks of the cutting face is controlled to be within 1%, the production efficiency is effectively improved, and the production cost is reduced.
Description
Technical field
The invention belongs to plate surface quality control techniques field, avoid especially a kind of winter heavy thickness medium and high carbon steel to cut the control method of delayed cracking.
Background technology
Along with the reduction gradually of temperature during winter production medium and high carbon steel, after the steel plate flame cutting of heavy thickness, there is a large amount of cutting delayed crackings in cut surface, substantially increase amount outside the plan, even produce waste product, have a strong impact on production cost and the contract encashment ratio of enterprise, for the steel industry that current meagre profit is moistened, enterprise produces a large amount of outside the plan, produces very adverse influence to production and management enviroment.Contract cannot be cashed on time simultaneously, also has a strong impact on enterprise in the in the eyes of image of client, affects the competitive power of enterprise product, produces larger detrimentally affect to enterprise's follow-up developments.
Cut surface delayed cracking concept is steel plate flame cutting or other thermal cutting rear surfaces, cutting rear surface flawless, but prolongation in time, and cut surface engenders crackle, and it is caused by cutting heat affected zone, surface phase transformation generation stress; Concrete both macro and micro pattern is shown in Fig. 1,2,3.
After winter medium and high carbon steel flame cutting, cut surface cooling rate is very fast, and cut surface generates martensitic stucture, and the density of this tissue is lower than austenite, so volume can expand after changing.Relative to changing the stereomutation brought, producing extremely strong structural stress, easily causing cut surface to occur retardance crackle.
Summary of the invention
The technical problem to be solved in the present invention is to provide the control method avoiding a kind of winter heavy thickness medium and high carbon steel to cut delayed cracking, effectively to eliminate steel plate fire tangent plane cutting stress.
For solving the problems of the technologies described above, the technical solution used in the present invention is: described high carbon steel sheet carries out slow cooling after normalizing treatment, flame cutting; In described high carbon steel sheet, C content is 0.45wt% ~ 0.47wt%, Mn content is 0.70wt% ~ 0.85wt%;
Described normalizing treatment process: normalizing temperature 850 DEG C ~ 880 DEG C, soaking time 1.5min/mm ~ 2.5min/mm.
In flame cutting process of the present invention, cutting temperature is >=100 DEG C.Wind sheltering cutting in described flame cutting process.
Annealing process of the present invention is: it is that in the burial pit of 300 DEG C ~ 350 DEG C or single-unit furnace, after insulation 1.5h ~ 2.5h, furnace cooling is to less than 100 DEG C that the high carbon steel sheet after cutting enters temperature.
The beneficial effect adopting technique scheme to produce is: the present invention adopts Composition Design and the normalizing treatment technique of high C, Mn, effectively reduce martensitic stucture, and reduce the stress concentration that thermal treatment causes, thus efficiently avoid the generation of delayed cracking.
During flame cutting of the present invention, temperature cutting is treated in employing, and wind sheltering cutting, to reduce the speed of cooling of the rear cut surface of steel plate cutting, enters burial pit in time and carries out stress-removal process after cutting; Thus more effectively reduce generation martensitic stucture, reduce structural stress and concentrate, after avoiding flame cutting, occur stress delayed cracking.
Flame cutting face delayed cracking of the present invention rate outside the plan controls, within 1%, to effectively raise production efficiency, reduces production cost.
Accompanying drawing explanation
Below in conjunction with the drawings and specific embodiments, the present invention is further detailed explanation.
Fig. 1 is the macro morphology figure of medium and high carbon steel cut surface delayed cracking;
Fig. 2 is medium and high carbon steel cut surface delayed cracking end (amplifying 50 times) shape appearance figure;
Fig. 3 is that medium and high carbon steel cut surface delayed cracking extends pattern (amplifying 50 times) figure to body;
Fig. 4 is metallographic structure (the amplifying 100 times) figure of embodiment 1 product;
Fig. 5 is metallographic structure (the amplifying 500 times) figure of embodiment 1 product;
Fig. 6 is metallographic structure (the amplifying 100 times) figure of embodiment 2 product;
Fig. 7 is metallographic structure (the amplifying 500 times) figure of embodiment 2 product;
Fig. 8 is metallographic structure (the amplifying 100 times) figure of embodiment 3 product;
Fig. 9 is metallographic structure (the amplifying 500 times) figure of embodiment 3 product;
Figure 10 is metallographic structure (the amplifying 100 times) figure of embodiment 4 product;
Figure 11 is metallographic structure (the amplifying 500 times) figure of embodiment 4 product.
Embodiment
The control method avoiding this winter heavy thickness medium and high carbon steel to cut delayed cracking adopts following technique:
(1) Composition Design: high carbon steel sheet more than thickness specification 120mm, adopts the Composition Design of high C, Mn, and C content is 0.45wt% ~ 0.47wt%, Mn content is 0.70wt% ~ 0.85wt%; Other compositions meet GB/T711-2008 standard.Like this, the generation of martensitic stucture is fundamentally reduced.
(2) normalizing treatment: normalizing temperature 850 DEG C ~ 880 DEG C, soaking time 1.5min/mm ~ 2.5min/mm steel plate thickness, air cooling.
(3) high-temperature machining: because steel plate thickness is thicker, it is more that cutting process absorbs heat, if cutting temperature is lower, after cutting, cooling rate is large, produces martensite volume more, produces structural stress and concentrate larger, therefore require cutting temperature >=100 DEG C of steel plate; Can adopt and treat temperature cutting, or cutting temperature carries out pre-thermal cutting lower than during this temperature.
(4) wind sheltering cutting: the speed of cooling reducing cutting process, avoids during cutting directly blowing the cutting of steel plate place in air port or cold wind, namely carries out wind sheltering cutting.If conditions permit preferably adopts asbestos or other lagging materials to cover cut surface, be suitably incubated.Steel plate cutting after, enter within 4h burial pit or single-unit furnace heating carry out the process that eliminates stress.
(5) stress-removal process: the temperature of burial pit or single-unit furnace is 300 DEG C ~ 350 DEG C, after steel plate enters stove insulation 1.5h ~ 2.5h in time, furnace cooling is to less than 100 DEG C.
Embodiment 1: this control method adopts following concrete technology.
Steel grade 45#, thickness specification 120mm, Composition Design (by weight percentage): C 0.46%, Mn 0.75%, other compositions meet GB/T711-2008 standard.
Technological process: (1) in car bottom furnace normalizing, normalizing temperature 860 DEG C ~ 870 DEG C, heating coefficient (soaking time) 1.5min/mm, air cooling.
(2) normalizing completes split requirement steel plate for treating temperature cutting, wind sheltering during cutting, cutting temperature 120 DEG C; After steel plate cutting, enter burial pit heating in 2.5 hours and carry out the process that eliminates stress.
(3) stress-removal process: burial pit Heating temperature 330 DEG C, after steel plate enters stove insulation 2h, furnace cooling is to room temperature 25 DEG C.
Fig. 4 and Fig. 5 be shown in by the organization chart of the 45# steel plate after the cutting of the present embodiment gained; From Fig. 4,5, steel plate organization type is ferrite+perlite, and steel plate grain fineness number is at 8.5 grades.Three point hardnesses of steel plate are: 175,186,178.Crackle is not there is in steel plate after 1 month stacks.
Embodiment 2: this control method adopts following concrete technology.
Steel grade 45#, thickness specification 180mm, Composition Design (by weight percentage): C 0.47%, Mn 0.85%, other compositions meet GB/T711-2008 standard.
(1) in car bottom furnace normalizing, normalizing temperature 860 DEG C ~ 880 DEG C, heating coefficient (soaking time) 1.5min/mm, air cooling.
(2) normalizing completes split requirement steel plate for treating temperature cutting, wind sheltering during cutting, cutting temperature 135 DEG C; After steel plate cutting, enter single-unit furnace heating in 2.5 hours and carry out the process that eliminates stress.
(3) stress-removal process: single-unit furnace Heating temperature 320 DEG C, after steel plate enters stove insulation 2.5h, furnace cooling is to room temperature 20 DEG C.
Fig. 6 and Fig. 7 be shown in by the organization chart of the 45# steel plate after the cutting of the present embodiment gained; From Fig. 6,7, steel plate organization type is ferrite+perlite, and steel plate grain fineness number is at 8 grades.Steel plate three point hardness is: 178,182,190.Crackle is not there is in steel plate after 2 months stack.
Embodiment 3: this control method adopts following concrete technology.
Steel grade 45#, thickness specification 300mm, Composition Design (by weight percentage): C 0.47%, Mn 0.78%, other compositions meet GB/T711-2008 standard.
(1) in car bottom furnace normalizing, normalizing temperature 860 DEG C ~ 880 DEG C, heating coefficient (soaking time) 1.8min/mm, air cooling.
(2) normalizing completes split requirement steel plate for treating temperature cutting, wind sheltering during cutting, cutting temperature 135 DEG C; After steel plate cutting, enter single-unit furnace heating in 2.5 hours and carry out the process that eliminates stress.
(3) stress-removal process: single-unit furnace Heating temperature 350 DEG C, after steel plate enters stove insulation 2h, furnace cooling is to room temperature 26 DEG C.
Fig. 8 and Fig. 9 be shown in by the organization chart of the 45# steel plate after the cutting of the present embodiment gained; From Fig. 8,9, steel plate organization type is ferrite+perlite, and steel plate grain fineness number is at 8 grades.Steel plate three point hardness is: 172,188,186.Crackle is not there is in steel plate after 1 first quarter moon is stacked.
Embodiment 4: this control method adopts following concrete technology.
Steel grade 45#, thickness specification 470mm, Composition Design (by weight percentage): C 0.47%, Mn 0.75%, other compositions meet GB/T711-2008 standard.
(1) in car bottom furnace normalizing, normalizing temperature 860 DEG C ~ 880 DEG C, heating coefficient (soaking time) 2.0min/mm, air cooling.
(2) normalizing completes split requirement steel plate for treating temperature cutting, wind sheltering during cutting, cutting temperature 132 DEG C; After steel plate cutting, enter burial pit heating in 2.0 hours and carry out the process that eliminates stress.
(3) stress-removal process: burial pit Heating temperature 330 DEG C, after steel plate enters stove insulation 1.5h in time, furnace cooling is to room temperature 28 DEG C.
Figure 10 and Figure 11 be shown in by the organization chart of the 45# steel plate after the cutting of the present embodiment gained; From Figure 10,11, steel plate organization type is ferrite+perlite, and steel plate grain fineness number is at 8 grades.Steel plate three point hardness is: 169,181,185.Crackle is not there is in steel plate after 1 month stacks.
Embodiment 5: this control method adopts following concrete technology.
Steel grade 45#, thickness specification 380mm, Composition Design (by weight percentage): C 0.45%, Mn 0.70%, other compositions meet GB/T711-2008 standard.
(1) in car bottom furnace normalizing, normalizing temperature 850 DEG C ~ 870 DEG C, heating coefficient (soaking time) 2.5min/mm, air cooling.
(2) steel plate is heated to 100 DEG C cut, wind sheltering during cutting; After steel plate cutting, enter burial pit heating in 4 hours and carry out the process that eliminates stress.
(3) stress-removal process: burial pit Heating temperature 300 DEG C, after steel plate enters stove insulation 2h in time, furnace cooling is to 90 DEG C.
The organization type of the 45# steel plate after the cutting of the present embodiment gained is ferrite+perlite, and steel plate grain fineness number is at 8.0 grades.Steel plate three point hardness is: 168,179,185.Crackle is not there is in steel plate after 1 month stacks.
Claims (4)
1. avoid winter heavy thickness medium and high carbon steel to cut a control method for delayed cracking, it is characterized in that: described high carbon steel sheet carries out slow cooling after normalizing treatment, flame cutting; In described high carbon steel sheet, C content is 0.45wt% ~ 0.47wt%, Mn content is 0.70wt% ~ 0.85wt%;
Described normalizing treatment process: normalizing temperature 850 DEG C ~ 880 DEG C, soaking time 1.5min/mm ~ 2.5min/mm.
2. avoid winter according to claim 1 heavy thickness medium and high carbon steel to cut the control method of delayed cracking, it is characterized in that: in described flame cutting process, cutting temperature is >=100 DEG C.
3. avoid winter according to claim 2 heavy thickness medium and high carbon steel to cut the control method of delayed cracking, it is characterized in that: wind sheltering cutting in described flame cutting process.
4. according to claim 1,2 or 3 winters stated avoid heavy thickness medium and high carbon steel to cut the control method of delayed cracking, it is characterized in that, described annealing process is: it is that in the burial pit of 300 DEG C ~ 350 DEG C or single-unit furnace, after insulation 1.5h ~ 2.5h, furnace cooling is to less than 100 DEG C that the high carbon steel sheet after cutting enters temperature.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109570688A (en) * | 2019-01-03 | 2019-04-05 | 南京钢铁股份有限公司 | A kind of method of gas flame cuttiug carbon steel blank |
| CN111922639A (en) * | 2020-07-29 | 2020-11-13 | 葛家玉 | Processing method of wear-resistant easy-to-form special steel |
| CN112921154A (en) * | 2021-01-25 | 2021-06-08 | 宝武杰富意特殊钢有限公司 | Method for manufacturing high-alloy martensite air valve steel |
| CN114147434A (en) * | 2021-12-24 | 2022-03-08 | 舞阳钢铁有限责任公司 | Method for improving cutting quality of medium and high carbon steel of ultra-thick plate |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102732710A (en) * | 2012-06-08 | 2012-10-17 | 舞阳钢铁有限责任公司 | Heat treatment method of steel plate with large thickness |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102732710A (en) * | 2012-06-08 | 2012-10-17 | 舞阳钢铁有限责任公司 | Heat treatment method of steel plate with large thickness |
Non-Patent Citations (1)
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| 刘利香等: "舞钢大厚度电渣钢板的研制开发", 《宽厚板》 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109570688A (en) * | 2019-01-03 | 2019-04-05 | 南京钢铁股份有限公司 | A kind of method of gas flame cuttiug carbon steel blank |
| CN111922639A (en) * | 2020-07-29 | 2020-11-13 | 葛家玉 | Processing method of wear-resistant easy-to-form special steel |
| CN112921154A (en) * | 2021-01-25 | 2021-06-08 | 宝武杰富意特殊钢有限公司 | Method for manufacturing high-alloy martensite air valve steel |
| CN112921154B (en) * | 2021-01-25 | 2022-12-30 | 宝武杰富意特殊钢有限公司 | Method for manufacturing high-alloy martensite air valve steel |
| CN114147434A (en) * | 2021-12-24 | 2022-03-08 | 舞阳钢铁有限责任公司 | Method for improving cutting quality of medium and high carbon steel of ultra-thick plate |
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