Smelting method of ingot 14Cr1MoR steel plate

Abstract

The invention discloses a smelting method of an ingot 14Cr1MoR steel plate, and belongs to the technical field of ferrous metallurgy. The smelting method comprises a steel ladle preparation process, an electric furnace smelting process, an LF refining furnace process, a VD vacuum furnace process and a casting process. In the LF refining furnace process, the final slag alkalinity is larger than or equal to 6.0 after LF refining, and slagging-off is conducted after LF refining. The 14Cr1MoR molten steel produced through the method is stable in internal quality, the molten steel is cast into steel ingots of different ingot types, the steel ingots are finally rolled into steel plates with the plate thickness of 100-125 mm, and the NB / T47013.3-2015 acceptance level Level TI level flaw detection qualification rate of the steel plates is larger than or equal to 98%.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a smelting method for an ingot-formed 14Cr1MoR steel plate. Background Art

[0002] As a high-performance low-alloy high-strength steel plate, 14Cr1MoR steel plate has excellent mechanical properties, corrosion resistance and welding performance. It has been widely used in many industrial fields and has strong market demand. Most steel mills produce 14Cr1MoR steel plates with continuous casting billets and the thickness of the steel plates is less than 100mm. With the development of large-scale equipment, downstream users have a sharp increase in demand for 14Cr1MoR steel plates with a thickness of more than 100mm. Users not only require large plate thickness but also require the steel plates to meet the NB / T47013.3-2015 acceptance level Level TI.

[0003] At present, the relevant patents in the industry mainly study the rolling performance of 14Cr1MoR steel plates with small plate thickness, and rarely involve the steelmaking and smelting production process of ingot-finished large-plate 14Cr1MoR steel plates and methods to improve the flaw detection pass rate. As the main production base of ingot-finished large-plate 14Cr1MoR steel plates, Wugang Company has continuously optimized and improved the smelting process of ingot-finished 14Cr1MoR steel plates, and finally produced low-P and low-S molten steel, and the internal control quality of the molten steel is stable. The molten steel is cast into ingots of different ingot shapes, and after the ingots are rolled into plates with a thickness of 100-125mm, the NB / T47013.3-2015 acceptance level Level TI flaw detection pass rate is ≥98%. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a smelting method for ingot-finished 14Cr1MoR steel plate. The method can achieve P≤0.007 and S≤0.002% of the molten steel, and the NB / T47013.3-2015 acceptance level Level TI level flaw detection pass rate of ≥98% after different ingot-shaped plates are rolled.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a smelting method of ingot-formed 14Cr1MoR steel plate, the smelting method includes a ladle preparation process, an electric furnace smelting process, an LF refining furnace process, a VD vacuum furnace process, and a casting process; in the LF refining furnace process, the basicity of the final slag after LF refining is ≥6.0, and the slag is removed after LF refining.

[0006] In the ladle preparation process of the present invention, a ladle with a flat ladle edge is selected to facilitate dephosphorization in the LF refining furnace.

[0007] The electric furnace smelting process of the present invention does not add materials when tapping steel, and tapping steel is oxygen-enriched, ensuring that C≤0.03% and P≤0.007% in the tapped steel water.

[0008] In the LF refining furnace process of the present invention, after the ladle is set, the phosphorus is firstly dephosphorized to P≤0.002%, and then an argon gas belt is connected to blow argon to avoid slag.

[0009] In the LF refining furnace process of the present invention, 0.3-0.7kg / t of carbon powder is added to the ladle in a state of large argon blowing after dephosphorization, 3-6kg / t of alloy ferrosilicon and 3-4kg / t of medium carbon ferromanganese are added after carbon addition, 5-7m / t of aluminum wire is fed, and ferromolybdenum and low chromium are added after aluminum feeding, and the amount of lime used is 10-14kg / t of steel.

[0010] In the VD vacuum furnace process of the present invention, the vacuum degree is maintained at ≤66Pa for 20 to 25 minutes, and non-oxidation soft blowing is performed for 8 to 12 minutes after breaking the vacuum.

[0011] In the casting process of the present invention, the overheat degree of the cast steel is controlled at 42-50°C.

[0012] In the smelting method of the present invention, P of the molten steel is less than or equal to 0.007% and S is less than or equal to 0.002%.

[0013] The 14Cr1MoR molten steel produced by the smelting method of the present invention is cast into steel ingots of different ingot shapes, and after the steel ingots are rolled into steel plates with a thickness of 100-125 mm, the NB / T47013.3-2015 acceptance level Level TI level flaw detection pass rate is ≥98%.

[0014] The chemical composition and mass percentage of the 14Cr1MoR steel plate produced by the method of the present invention are: C: 0.05-0.15%, Si: 0.5-0.8%, Mn: 0.40-0.65%, P≤0.007%, S≤0.005%, Ni≤0.20%, Cr: 1.15-1.50%, Mo: 0.45-0.65%, and the balance is Fe and unavoidable impurities.

[0015] The smelting method of the invention uses an electric furnace to tap steel without adding materials, performs dephosphorization, deoxidation alloying and slag making operations in the LF refining furnace process, reasonably controls degassing and soft blowing time in the VD process, and controls reasonable superheat in the casting process, so as to finally obtain 14Cr1MoR molten steel with P≤0.007% and S≤0.002%.

[0016] The beneficial effects of the above technical scheme are as follows: 1. The present invention selects a ladle with good rim in the ladle preparation process, oxygen-enriched steel is tapped in the electric furnace smelting process, the LF refining furnace first dephosphorizes and then carbon powder + silicon-manganese alloy weak deoxidation, the VD vacuum furnace process is maintained for 20-25 minutes, and the casting process has an overheating temperature of 42-50°C, which not only achieves the low P and low S components of the molten steel, but also improves the internal quality of the molten steel. 2. The 14Cr1MoR produced by the smelting method provided by the present invention achieves LF final slag basicity ≥ 6.0, the molten steel composition is controllable, and the molten steel P ≤ 0.007%, S ≤ 0.002%; after rolling into a plate with a thickness of 100-125mm, the NB / T47013.3-2015 acceptance level Level TI level flaw detection pass rate ≥ 98%. 3. The present invention not only develops a smelting method for ingot-finished large-plate 14Cr1MoR steel plate, but also provides a certain reference value for the smelting of other types of low-phosphorus CrMo steel. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below in conjunction with specific embodiments.

[0018] Example 1

[0019] A smelting method for ingot-finished 14Cr1MoR steel plate, comprising a ladle preparation process, an electric furnace smelting process, an LF refining furnace process, a VD vacuum furnace process, and a casting process; the details are as follows:

[0020] (1) Ladle preparation process: the ladle edge is flat;

[0021] (2) Electric furnace smelting process: No materials are added when tapping steel, oxygen-enriched steel is tapped to ensure that the following contents of molten steel are present: C: 0.03%, P: 0.007%.

[0022] (3) LF refining furnace process: After sitting in the ladle, dephosphorization is carried out outside the furnace to a phosphorus content of 0.002%, and then argon blowing is carried out to avoid slag.

[0023] (4) LF refining furnace process: after dephosphorization, add 0.7kg / t of carbon powder to the ladle under the condition of large argon blowing; after carbon addition, add 6kg / t of alloy ferrosilicon and 4kg / t of medium carbon ferromanganese; after feeding aluminum, add 7m / t of aluminum wire; after feeding aluminum, add ferromolybdenum and low chromium; after feeding aluminum, add 14kg / t of lime; after LF, the basicity of the final slag is 7.0; after LF refining, remove the slag.

[0024] (4) VD vacuum furnace process: maintain vacuum degree at 66Pa for 25min, and then soft blow at normal pressure without oxidation for 12min after destruction.

[0025] (5) Casting process: liquidus 1518℃, steel pouring temperature 1568℃, superheat 50℃.

[0026] The 14Cr1MoR steel plate (ingot shape 41*2, plate thickness 125mm) produced by the smelting method of the present invention has a P content of 0.007% and an S content of 0.0016% in the molten steel. Both the NBTI level flaw detection of the two steel ingots after rolling are qualified.

[0027] Example 2

[0028] A smelting method for ingot-finished 14Cr1MoR steel plate, comprising a ladle preparation process, an electric furnace smelting process, an LF refining furnace process, a VD vacuum furnace process, and a casting process; the details are as follows:

[0029] (1) Ladle preparation process: the ladle edge is flat;

[0030] (2) Electric furnace smelting process: No materials are added when tapping steel, oxygen-enriched steel is tapped to ensure that the following contents of molten steel are present: C: 0.025%, P: 0.007%.

[0031] (3) LF refining furnace process: After sitting in the ladle, dephosphorization is carried out outside the furnace to a phosphorus content of 0.002%, and then argon blowing is carried out to avoid slag.

[0032] (4) LF refining furnace process: after dephosphorization, add 0.3kg / t of carbon powder to the ladle under the condition of large argon blowing; after carbon addition, add 3kg / t of alloy ferrosilicon and 3kg / t of medium carbon ferromanganese; feed 5m / t of aluminum wire; after aluminum feeding, add ferromolybdenum and low chromium; the amount of lime is 10kg / t of steel; the final slag basicity is 6.0 after LF refining; and the slag is removed after LF refining.

[0033] (4) VD vacuum furnace process: maintain the vacuum degree at 65Pa for 20min, and then soft blow at normal pressure without oxidation for 8min after destruction.

[0034] (5) Casting process: liquidus 1518°C, steel pouring temperature 1560°C, superheat 42°C.

[0035] The 14Cr1MoR steel plate (ingot shape 41*2, plate thickness 100mm) produced by the smelting method of the present invention has molten steel P: 0.006%, S: 0.0014%, and 2 steel ingots are qualified in NBTI level flaw detection after rolling.

[0036] Example 3

[0037] A smelting method for ingot-finished 14Cr1MoR steel plate, comprising a ladle preparation process, an electric furnace smelting process, an LF refining furnace process, a VD vacuum furnace process, and a casting process; the details are as follows:

[0038] (1) Ladle preparation process: the ladle edge is flat;

[0039] (2) Electric furnace smelting process: No materials are added when tapping steel, oxygen-enriched steel is tapped to ensure that the following contents of molten steel are present: C: 0.02%, P: 0.006%.

[0040] (3) LF refining furnace process: After sitting in the ladle, dephosphorization is carried out outside the furnace to a phosphorus content of 0.001%, and then argon blowing is carried out to avoid slag.

[0041] (4) LF refining furnace process: after dephosphorization, add 0.5kg / t of carbon powder to the ladle under the condition of large argon blowing; after carbon addition, add 4kg / t of alloy ferrosilicon and 3.5kg / t of medium carbon ferromanganese; after feeding aluminum wire, add 6m / t of steel; after feeding aluminum, add ferromolybdenum and low chromium; after feeding aluminum, add lime and 12kg / t of steel; after LF, the basicity of the final slag is 6.5; after LF refining, remove the slag.

[0042] (4) VD vacuum furnace process: maintain vacuum degree at 66Pa for 22min, and then soft blow at normal pressure without oxidation for 10min after destruction.

[0043] (5) Casting process: liquidus 1517°C, steel pouring temperature 1563°C, superheat 46°C.

[0044] The 14Cr1MoR (ingot shape 41*2, plate thickness 115mm) produced by the smelting method of the present invention has a P content of 0.006% and an S content of 0.0011% in the molten steel. Both the NBTI level flaw detection of the two steel ingots after rolling are qualified.

[0045] Example 4

[0046] A smelting method for ingot-finished 14Cr1MoR steel plate, comprising a ladle preparation process, an electric furnace smelting process, an LF refining furnace process, a VD vacuum furnace process, and a casting process; the details are as follows:

[0047] (1) Ladle preparation process: the ladle edge is flat;

[0048] (2) Electric furnace smelting process: No materials are added when tapping steel, oxygen-enriched steel is tapped to ensure that the following contents of molten steel are present: C: 0.02%, P: 0.004%.

[0049] (3) LF refining furnace process: After sitting in the ladle, dephosphorization is carried out outside the furnace to a phosphorus content of 0.001%, and then argon blowing is carried out to avoid slag.

[0050] (4) LF refining furnace process: after dephosphorization, add 0.6kg / t carbon powder to the ladle under the condition of large argon blowing; after carbon addition, add 5kg / t alloy ferrosilicon and 3.6kg / t medium carbon ferromanganese; feed 6.5m / t aluminum wire; after aluminum feeding, add ferromolybdenum and low chromium; the amount of lime is 11kg / t steel; the final slag basicity is 6.2 after LF refining; after LF refining, remove the slag.

[0051] (4) VD vacuum furnace process: maintain vacuum degree at 66Pa for 23min, and then soft blow at normal pressure without oxidation for 9min after destruction.

[0052] (5) Casting process: liquidus 1518°C, steel pouring temperature 1565°C, superheat 47°C.

[0053] The 14Cr1MoR (ingot shape 45*2, plate thickness 120mm) produced by the smelting method of the present invention has a P content of 0.006% and an S content of 0.0014% in the molten steel. Both of the two steel ingots are qualified in NBTI level flaw detection after rolling.

[0054] Example 5

[0055] A smelting method for ingot-finished 14Cr1MoR steel plate, comprising a ladle preparation process, an electric furnace smelting process, an LF refining furnace process, a VD vacuum furnace process, and a casting process; the details are as follows:

[0056] (1) Ladle preparation process: the ladle edge is flat;

[0057] (2) Electric furnace smelting process: No materials are added when tapping steel, oxygen-enriched steel is tapped to ensure that the following contents of the tapped steel are present: C: 0.023%, P: 0.005%.

[0058] (3) LF refining furnace process: After sitting in the ladle, dephosphorization is carried out outside the furnace to a phosphorus content of 0.002%, and then argon blowing is carried out to avoid slag.

[0059] (4) LF refining furnace process: after dephosphorization, add 0.5kg / t of carbon powder to the ladle under the condition of large argon blowing; after carbon addition, add 4.5kg / t of alloy ferrosilicon and 4kg / t of medium carbon ferromanganese; after feeding aluminum, add 6m / t of aluminum wire; after feeding aluminum, add ferromolybdenum and low chromium; after feeding aluminum, add 13kg / t of lime; after LF, the basicity of the final slag is 6.4; after LF refining, remove the slag.

[0060] (4) VD vacuum furnace process: maintain vacuum degree at 66Pa for 21min, and then soft blow at normal pressure without oxidation for 8min after destruction.

[0061] (5) Casting process: liquidus 1517°C, steel pouring temperature 1566°C, superheat 49°C.

[0062] The 14Cr1MoR (ingot type 22+28*2, plate thickness 100mm+125mm) produced by the smelting method of the present invention has a P content of 0.006% and an S content of 0.0012% in the molten steel. All three steel ingots are qualified in NBTI level flaw detection after rolling.

[0063] Example 6

[0064] A smelting method for ingot-finished 14Cr1MoR steel plate, comprising a ladle preparation process, an electric furnace smelting process, an LF refining furnace process, a VD vacuum furnace process, and a casting process; the details are as follows:

[0065] (1) Ladle preparation process: the ladle edge is flat;

[0066] (2) Electric furnace smelting process: No materials are added when tapping steel, oxygen-enriched steel is tapped to ensure that the following contents of molten steel are present: C: 0.01%, P: 0.003%.

[0067] (3) LF refining furnace process: After sitting in the ladle, dephosphorization is carried out outside the furnace to a phosphorus content of 0.001%, and then argon blowing is carried out to avoid slag.

[0068] (4) LF refining furnace process: after dephosphorization, add 0.6kg / t of carbon powder to the ladle under the condition of large argon blowing; after carbon addition, add 5kg / t of alloy ferrosilicon and 4kg / t of medium carbon ferromanganese; after feeding aluminum, add 6m / t of aluminum wire; after feeding aluminum, add ferromolybdenum and low chromium; after adding aluminum, add 13.5kg / t of lime; after LF, the basicity of the final slag is 6.6; after LF refining, remove the slag.

[0069] (4) VD vacuum furnace process: maintain vacuum degree at 66Pa for 22min, and then soft blow at normal pressure without oxidation for 11min after destruction.

[0070] (5) Casting process: pouring steel with cover, liquidus 1517℃, pouring temperature 1560℃, overheat 43℃.

[0071] The 14Cr1MoR (ingot shape 51*2, plate thickness 125mm) produced by the smelting method of the present invention has a P content of 0.006% and an S content of 0.0015% in the molten steel. Both of the two steel ingots are qualified in NBTI level flaw detection after rolling.

[0072] Example 7

[0073] A smelting method for ingot-finished 14Cr1MoR steel plate, comprising a ladle preparation process, an electric furnace smelting process, an LF refining furnace process, a VD vacuum furnace process, and a casting process; the details are as follows:

[0074] (1) Ladle preparation process: the ladle edge is flat;

[0075] (2) Electric furnace smelting process: No materials are added when tapping steel, oxygen-enriched steel is tapped to ensure that the following contents of molten steel are present: C: 0.024%, P: 0.004%.

[0076] (3) LF refining furnace process: After sitting in the ladle, dephosphorization is carried out outside the furnace to a phosphorus content of 0.002%, and then argon blowing is carried out to avoid slag.

[0077] (4) LF refining furnace process: after dephosphorization, add 0.4kg / t of carbon powder to the ladle under the condition of large argon blowing; after carbon addition, add 5kg / t of alloy ferrosilicon and 3kg / t of medium carbon ferromanganese; feed 5.5m / t of aluminum wire; after aluminum feeding, add ferromolybdenum and low chromium; the amount of lime is 12.5kg / t of steel; the basicity of the final slag after LF is 6.3; after LF refining, remove the slag.

[0078] (4) VD vacuum furnace process: maintain vacuum degree at 66Pa for 24min, and then soft blow at normal pressure without oxidation for 12min after destruction.

[0079] (5) Casting process: pouring steel with buckle cover, liquidus 1518℃, pouring steel temperature 1560℃, overheat 42℃.

[0080] The 14Cr1MoR (ingot shape 35*3, plate thickness 115mm) produced by the smelting method of the present invention has a P content of 0.006% and an S content of 0.0012% in the molten steel. All three steel ingots are qualified in NBTI level flaw detection after rolling.

[0081] Table 1 Chemical composition and percentage content of steel plates in various examples (wt%)

[0082]

[0083]

[0084] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A smelting method for ingot-formed 14Cr1MoR steel plate, characterized in that: The smelting method comprises a ladle preparation process, an electric furnace smelting process, an LF refining furnace process, a VD vacuum furnace process, and a casting process; in the LF refining furnace process, the final slag basicity after LF refining is ≥6.0, and the slag is removed after LF refining.

2. The smelting method of the ingot-formed 14Cr1MoR steel plate according to claim 1, characterized in that: In the ladle preparation process, a ladle with a flat brim is selected.

3. The smelting method of the ingot-formed 14Cr1MoR steel plate according to claim 1, characterized in that: In the electric furnace smelting process, no material is added during steel tapping and oxygen-enriched steel tapping is performed, thereby ensuring that C≤0.03% and P≤0.007% in the tapped steel.

4. The smelting method of the ingot-formed 14Cr1MoR steel plate according to claim 1, characterized in that: In the LF refining furnace process, after the ladle is set, the phosphorus is first dephosphorized to P≤0.002%, and then an argon gas belt is connected to blow argon to avoid slag.

5. The smelting method of the ingot-formed 14Cr1MoR steel plate according to claim 1, characterized in that: In the LF refining furnace process, after dephosphorization, 0.3-0.7kg / t of carbon powder is added to the ladle under the condition of large argon blowing, 3-6kg / t of alloy ferrosilicon and 3-4kg / t of medium carbon ferromanganese are added after carbon addition, 5-7m / t of aluminum wire is fed, and ferromolybdenum and low chromium are added after aluminum feeding, and the amount of lime used is 10-14kg / t of steel.

6. The smelting method of the ingot-formed 14Cr1MoR steel plate according to claim 1, characterized in that: In the VD vacuum furnace process, the vacuum degree is maintained at ≤66Pa for 20 to 25 minutes, and non-oxidation soft blowing is performed for 8 to 12 minutes after breaking the air.

7. The method for smelting 14Cr1MoR steel plate from ingots according to claim 1, characterized in that: In the casting process, the overheating degree of the cast steel is controlled at 42-50°C.

8. The smelting method of ingot-formed 14Cr1MoR steel plate according to any one of claims 1 to 7, characterized in that: In the smelting method, P≤0.007% and S≤0.002% of the molten steel.

9. The smelting method of ingot-formed 14Cr1MoR steel plate according to any one of claims 1 to 7, characterized in that: The 14Cr1MoR molten steel produced by the smelting method is cast into steel ingots of different ingot shapes, and after the steel ingots are rolled into steel plates with a thickness of 100-125 mm, the NB / T47013.3-2015 acceptance level Level TI level flaw detection pass rate is ≥98%.

10. The smelting method of ingot material 14Cr1MoR according to any one of claims 1 to 7, characterized in that: The chemical composition and mass percentage of the 14Cr1MoR steel plate produced by the smelting method are: C: 0.05-0.15%, Si: 0.5-0.8%, Mn: 0.40-0.65%, P≤0.007%, S≤0.005%, Ni: ≤0.02%, Cr: 1.15-1.50%, Mo: 0.45-0.65%, and the balance is Fe and unavoidable impurities.

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