13MnNiMoR thick steel plate for boiler drum and production method of 13MnNiMoR thick steel plate

Abstract

The invention discloses a 13MnNiMoR thick steel plate for a boiler drum, which is characterized by comprising the following components in percentage by weight: 0.12 to 0.15 percent of C, 1.30 to 1.50 percent of Mn, 0.20 to 0.40 percent of Si, less than or equal to 0.015 percent of P, less than or equal to 0.005 percent of S, 0.010 to 0.020 percent of Nb, 0.020 to 0.040 percent of V, 0.20 to 0.40 percent of Cr, 0.20 to 0.40 percent of Mo, 0.80 to 1.00 percent of Ni, 0.020 to 0.050 percent of Alt, 0.030 to 0.050 percent of Nb + V and the balance of Fe and impurities, and a production method of the 13MnNiMoR thick steel plate comprises a steelmaking process, a blank heating process, a rolling process and a tempering heat treatment process. According to the method, the large rolling reduction technology that the large-thickness continuous casting billet guarantees the rolling compression ratio of 3 times or above, Nb + V microalloying is conducted, and the reduction of three passes is guaranteed to be larger than or equal to 38 mm through one-stage rolling is adopted, the continuous casting billet rolling thickness is larger than 100-150 mm, the 13MnNiMoR thick steel plate for the boiler drum is completed, the steel plate is excellent in performance, the 0-DEG C impact at the position with the thickness being 1 / 4 is larger than or equal to 200 J, the 0-DEG C impact at the center is larger than or equal to 150 J, meanwhile, the production process is simple, and the production cost is low. And the production cost is low, and economical and efficient production of steel plates can be achieved.

Description

Technical Field

[0001] The invention relates to a 13MnNiMoR thick steel plate for a boiler drum and a production method thereof. Background Art

[0002] 13MnNiMoR is a low alloy high strength steel designed for medium and low temperature and high pressure environments. It is widely used in boiler and pressure vessel manufacturing, mainly for applications that need to withstand high internal pressure and certain temperature conditions. It requires the steel plate to have not only a high strength grade, but also strict requirements on the product's low temperature impact performance, high temperature tensile performance, simulated post-weld heat treatment performance, internal quality, etc. As boiler container equipment develops towards large-scale, the demand for 13MnNiMoR boiler drum steel thick plates with a thickness of more than 100-150mm is increasing.

[0003] In order to achieve the best mechanical properties of 13MnNiMoR boiler drum steel plates with a thickness of more than 100-150mm, especially the requirements of high strength, low temperature toughness, high temperature performance, etc., die-cast ingots, electroslag remelting, composite billets, etc. are generally used for rolling production, and tempering, normalizing accelerated cooling + tempering heat treatment processes are used for production, which increases the complexity and cost of the manufacturing process. With the progress of continuous casting technology, especially the construction and use of 400-460mm thick continuous casting billets, sufficient compression ratio can be guaranteed, and the conditions for rolling continuous casting billets to produce 13MnNiMoR thick plates are met.

[0004] Application No. 201210492603.9, a low-alloy high-strength steel plate for a thick boiler drum and a manufacturing method thereof, the invention adopts steel ingots to roll the steel plate, the yield rate is low, and warm loading, warm delivery and initial rolling are required, and the cost of raw materials and rolling is high; the invention adds 0.004-0.010% Ti, which is not conducive to the impact performance, especially the impact performance of the core of the continuous casting billet rolled thick plate; the invention adopts normalizing accelerated cooling + tempering heat treatment process for production, with many production processes and high production costs.

[0005] Application No. 201310736922.4, a 13MnNiMoR steel plate for pressure vessels and a production method thereof, the invention adopts steel ingots to roll the steel plate, the yield rate is low, and the raw material and rolling costs are high; the invention adds 0.08-0.18% Nb, and the alloy content is high; the invention adopts tempering, that is, quenching + tempering heat treatment process, the production process is multiple, and the production cost is high.

[0006] Application No. 201210223523.3, a boiler drum steel with a thickness of ≥80 mm and a production method thereof. The invention adopts a low-frequency bipolar series slab electroslag furnace for electroslag remelting, smelting, ingot extraction, and shrinkage compensation. The production process is complex and the production cost is high; Application No. 201410709954.X, a production method for high-strength and extra-thick boiler drum steel plate. The invention adopts ingot surface cleaning and combined ingot vacuum sealing welding to obtain a welded composite ingot for rolling. The production process is complex and the production cost is high. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a production process for eliminating the magnetism of the end face of round steel in view of the shortcomings of the above-mentioned prior art, solve the magnetism problem of the end face of steel, control the magnetism of the end face of steel to be less than 5GS, ensure that the welding liquid flows evenly during welding, and ensure the welding quality.

[0008] The technical solution of the present invention to solve the above technical problems is: a 13MnNiMoR thick steel plate for a boiler drum, wherein the components are as follows by weight percentage: C 0.12-0.15%, Mn 1.30-1.50%, Si 0.20-0.40%, P ≤0.015%, S ≤0.005%, Nb 0.010-0.020%, V 0.020-0.040%, Cr: 0.20-0.40%, Mo: 0.20-0.40%, Ni 0.80-1.00%, Alt 0.020-0.050%, while satisfying Nb+V 0.030-0.050%, and the rest is Fe and impurities.

[0009] The present invention further defines the scheme: Preferably, the composition of the 13MnNiMoR thick steel plate is as follows by weight percentage: C 0.14%, Mn 1.42%, Si0.28%, P 0.011%, S 0.002%, Nb 0.01%, V 0.028%, Cr: 0.25%, Mo: 0.26%, Ni 0.83%, Alt0.029%, while Nb+V 0.038%, and the rest is Fe and impurities.

[0010] Preferably, the composition of the 13MnNiMoR thick steel plate is as follows by weight percentage: C 0.13%, Mn 1.36%, Si0.23%, P 0.009%, S 0.001%, Nb 0.015%, V 0.032%, Cr: 0.27%, Mo: 0.25%, Ni 0.89%, Alt0.038%, while Nb+V 0.047%, and the rest is Fe and impurities.

[0011] Preferably, the composition of the 13MnNiMoR thick steel plate is as follows by weight percentage: C 0.15%, Mn 1.35%, Si0.22%, P 0.007%, S 0.001%, Nb 0.018%, V 0.031%, Cr: 0.31%, Mo: 0.33%, Ni 0.32%, Alt0.042%, while Nb+V 0.049%, and the rest is Fe and impurities.

[0012] The present invention provides a production method of a 13MnNiMoR thick steel plate for a boiler drum, which specifically comprises the following steps: (1) Steelmaking process: molten steel is smelted according to the above chemical composition and continuously cast into slabs, with Ti less than 0.004% and the center segregation of the slab being Class C and not exceeding Grade 1.0; (2) Heating process: The ingot is heated in a heating furnace, with a heating coefficient of 10.0-15.0 min / cm and a heating temperature of 1200-1240°C; (3) Rolling process: adopt a one-stage large reduction rolling process, the rolling reduction requirements are 3-5 passes with a large reduction of ≥38mm and a reduction rate of ≥18%; the last 1-2 passes with a small reduction of 5-15mm and a reduction rate of 2-7%, so as to better control the thickness and shape of the steel plate; the final rolling temperature is ≥1010℃, and the steel plate is cooled in air after rolling; (4) Tempering process: The tempering heat treatment temperature is 640-680℃, the holding time in the furnace is 2.5-4.0min / mm, and the tempering is followed by air cooling to room temperature.

[0013] The smelting in the above (1) specifically includes: converter smelting, LF refining, RH vacuum treatment and then continuous casting, wherein the converter tapping temperature is 1620-1680°C, LF refining is for alloying Cr, Mo, Ni, etc., RH refining vacuum treatment time is ≥15 minutes, and the continuous casting molten steel superheat is 5-20°C.

[0014] The invention has the following beneficial effects: the invention adopts Nb+V microalloying and one-stage large reduction rolling process, that is, the one-stage rolling ensures that the reduction of three passes is ≥38mm, the single-pass large reduction of the last 3-5 passes in the one-stage large reduction is ≥38mm, the rolling penetration deformation is ensured, the core microstructure performance of the thick plate is improved, the last 1-2 passes have a small reduction of 5-15mm, and the thickness and shape of the steel plate can be better controlled; the Nb+V microalloying further improves the strength and impact toughness of the steel plate after rolling and tempering, and does not add Ti to avoid deteriorating the impact performance of the core of the thick plate, so that the 0°C impact of 1 / 4 of the thick plate is ≥200J and the 0°C impact of the core is ≥150J. The invention realizes that the hot rolling+tempering process replaces the existing post-rolling quenching and tempering, normalizing+tempering heat treatment process, cancels the normalizing heat treatment process, has a simple production process, and has a low production cost, can realize the economical and efficient production of steel plates, and meets the manufacturing and service requirements of boiler pressure vessels. DETAILED DESCRIPTION Example

[0015] The present embodiment provides a 13MnNiMoR thick steel plate for a boiler drum, with a thickness of 115 mm, and the components by weight percentage are: C 0.14%, Mn 1.42%, Si 0.28%, P 0.011%, S 0.002%, Nb 0.01%, V 0.028%, Cr: 0.25%, Mo: 0.26%, Ni 0.83%, Alt 0.029%, while satisfying Nb+V 0.038%, and the rest is Fe and impurities.

[0016] This embodiment provides a method for producing a 13MnNiMoR thick steel plate for a boiler drum, which specifically comprises the following steps: (1) Steelmaking process: molten steel is smelted according to the above chemical composition and continuously cast into slabs, and Ti is required to be less than 0.004%, and the center segregation of the slab is C and does not exceed level 1.0, wherein the continuous casting is carried out after converter smelting, LF refining, and RH vacuum treatment, the converter tapping temperature is 1620°C, LF refining is used for alloying Cr, Mo, Ni, etc., the RH refining vacuum treatment time is 18 minutes, the continuous casting molten steel superheat is 6°C, the continuous casting process adopts dynamic soft reduction technology, and the casting is a 370 mm continuous casting slab; (2) Heating process: The ingot is heated in a heating furnace, with a heating coefficient of 11.5 min / cm and a heating temperature of 1207°C; (3) Rolling process: A one-stage high-reduction rolling process is adopted. The rolling reduction requirements are that the single-pass maximum reduction is 38-42mm and the reduction rate is 18-22% in the last 3-5 passes; the last 1-2 passes have a small reduction of 6-10mm and a reduction rate of 3-5% in order to better control the thickness and shape of the steel plate; the final rolling temperature is 1026℃, and the steel plate is cooled in air after rolling; (4) Tempering process: The tempering heat treatment temperature is 672°C, the holding time in the furnace is 412 min, and the tempering is followed by air cooling to room temperature. Example

[0017] A 13MnNiMoR thick steel plate for a boiler drum has a thickness of 130 mm and the following components by weight percentage: C 0.13%, Mn 1.36%, Si 0.23%, P 0.009%, S 0.001%, Nb 0.015%, V 0.032%, Cr: 0.27%, Mo: 0.25%, Ni 0.89%, Alt 0.038%, while Nb+V 0.047%, and the rest is Fe and impurities.

[0018] The present invention provides a production method of a 13MnNiMoR thick steel plate for a boiler drum, which specifically comprises the following steps: (1) Steelmaking process: smelting molten steel according to the above chemical composition and continuously casting into slabs, and requiring Ti < 0.004%, and the center segregation of the slab to be C and not more than 1.0 level, wherein the continuous casting is carried out after converter smelting, LF refining, and RH vacuum treatment, the converter tapping temperature is 1640°C, LF refining is used for alloying Cr, Mo, Ni, etc., the RH refining vacuum treatment time is 20 minutes, the continuous casting molten steel superheat is 12°C, the continuous casting process adopts dynamic soft reduction technology, and the casting is a 460 mm continuous casting slab; (2) Heating process: The ingot is heated in a heating furnace, with a heating coefficient of 11.9 min / cm and a heating temperature of 1213°C; (3) Rolling process: A one-stage large reduction rolling process is adopted. The rolling reduction requirements are that the maximum reduction of the last 3-5 passes is 38-42 mm and the reduction rate is 18-20%; the last 1-2 passes have a small reduction of 7-11 mm and a reduction rate of 2-4% in order to better control the thickness and shape of the steel plate; the final rolling temperature is 1014°C, and the steel plate is cooled in air after rolling; (4) Tempering process: The tempering heat treatment temperature is 658°C, the holding time in the furnace is 465 min, and the tempering is followed by air cooling to room temperature. Example

[0019] A 13MnNiMoR thick steel plate for a boiler drum has a thickness of 150 mm and the following components by weight percentage: C 0.15%, Mn 1.35%, Si 0.22%, P 0.007%, S 0.001%, Nb 0.018%, V 0.031%, Cr: 0.31%, Mo: 0.33%, Ni 0.32%, Alt 0.042%, while Nb+V 0.049%, and the rest is Fe and impurities.

[0020] The present invention provides a production method of a 13MnNiMoR thick steel plate for a boiler drum, which specifically comprises the following steps: (1) Steelmaking process: smelting molten steel according to the above chemical composition and continuously casting into slabs, and requiring Ti < 0.004%, and the center segregation of the slab to be C and not more than 1.0 level, wherein the continuous casting is carried out after converter smelting, LF refining, and RH vacuum treatment, the converter tapping temperature is 1680°C, LF refining is used for alloying Cr, Mo, Ni, etc., the RH refining vacuum treatment time is 25 minutes, the continuous casting molten steel superheat is 15°C, the continuous casting process adopts dynamic soft reduction technology, and the casting is a 460 mm continuous casting slab; (2) Heating process: The ingot is heated in a heating furnace, with a heating coefficient of 12.6 and a heating temperature of 1225°C; (3) Rolling process: A one-stage high-reduction rolling process is adopted. The rolling reduction requirements are 38-40mm for the last 3-5 passes and 18-19% for the reduction rate; the last 1-2 passes have a small reduction of 8-13mm and 2-7% for the reduction rate, so as to better control the thickness and shape of the steel plate; the final rolling temperature is 1013℃, and the steel plate is cooled in the air after rolling; (4) Tempering process: The tempering heat treatment temperature is 655℃, the holding time in the furnace is 536, and the tempering is followed by air cooling to room temperature.

[0021] The 13MnNiMoR thick steel plate for the boiler drum in the embodiment of the present invention has a thickness of 100-150 mm, a yield strength of 509-546 MPa, a tensile strength of 620-655 MPa, an elongation after fracture of 20%-22.5%, an average transverse impact energy at 0°C at 1 / 4 of the thickness of ≥200 J, and an average transverse impact energy at 0°C at 1 / 2 of the thickness of ≥150 J.

[0022] In addition to the above embodiments, the present invention may also have other implementation modes. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope required by the present invention.

Claims

1. A 13MnNiMoR thick steel plate for boiler drum, characterized in that: Its composition by weight percentage is: C0.12-0.15%, Mn 1.30-1.50%, Si 0.20-0.40%, P ≤0.015%, S ≤0.005%, Nb 0.010-0.020%, V 0.020-0.040%, Cr: 0.20-0.40%, Mo: 0.20-0.40%, Ni 0.80-1.00%, Alt 0.020-0.050%, while satisfying Nb+V 0.030-0.050%, and the rest is Fe and impurities.

2. The 13MnNiMoR thick steel plate for boiler drum according to claim 1, characterized in that: The composition of the 13MnNiMoR thick steel plate is as follows by weight percentage: C 0.14%, Mn 1.42%, Si 0.28%, P 0.011%, S0.002%, Nb 0.01%, V 0.028%, Cr: 0.25%, Mo: 0.26%, Ni 0.83%, Alt 0.029%, while satisfying Nb+V0.038%, and the rest is Fe and impurities.

3. The 13MnNiMoR thick steel plate for boiler drum according to claim 1, characterized in that: The composition of the 13MnNiMoR thick steel plate is as follows by weight percentage: C 0.13%, Mn 1.36%, Si 0.23%, P 0.009%, S0.001%, Nb 0.015%, V 0.032%, Cr: 0.27%, Mo: 0.25%, Ni 0.89%, Alt 0.038%, while satisfying Nb+V0.047%, and the rest is Fe and impurities.

4. The 13MnNiMoR thick steel plate for boiler drum according to claim 1, characterized in that: The composition of the 13MnNiMoR thick steel plate is as follows by weight percentage: C 0.15%, Mn 1.35%, Si 0.22%, P 0.007%, S0.001%, Nb 0.018%, V 0.031%, Cr: 0.31%, Mo: 0.33%, Ni 0.32%, Alt 0.042%, while satisfying Nb+V0.049%, and the rest is Fe and impurities.

5. The method for producing a 13MnNiMoR thick steel plate for a boiler drum according to any one of claims 1 to 4, characterized in that: The specific steps include: (1) Steelmaking process: molten steel is smelted according to the above chemical composition and continuously cast into slabs, with Ti less than 0.004% and the center segregation of the slab being Class C and not exceeding Grade 1.0; (2) Heating process: The ingot is heated in a heating furnace, with a heating coefficient of 10.0-15.0 min / cm and a heating temperature of 1200-1240°C; (3) Rolling process: adopt a one-stage large reduction rolling process, the rolling reduction requires the last 3-5 passes to have a large reduction of ≥38mm and a reduction rate of ≥18%; the last 1-2 passes to have a small reduction of 5-15mm and a reduction rate of 2-7%, so as to better control the thickness and shape of the steel plate; the final rolling temperature is ≥1010℃, and the steel plate is cooled in air after rolling; (4) Tempering process: The tempering heat treatment temperature is 640-680℃, the holding time in the furnace is 2.5-4.0min / mm, and the tempering is followed by air cooling to room temperature.

6. The method for producing a 13MnNiMoR thick steel plate for a boiler drum according to claim 5, characterized in that: The smelting in (1) specifically includes: converter smelting, LF refining, RH vacuum treatment and then continuous casting, wherein the converter tapping temperature is 1620-1680°C, LF refining is used for alloying Cr, Mo, Ni, etc., RH refining vacuum treatment time is ≥15 minutes, and the continuous casting molten steel superheat is 5-20°C.