Production method of q355me wind power steel

Abstract

The application discloses a production method of Q355ME wind power steel, and discloses related production processes and parameter control; the Q355ME wind power steel comprises the following chemical components in percentage by weight: C: 0.065-0.085%; Si: 0.3-0.4%; Mn: 1.4-1.5%; Nb: 0.025-0.035%; Ti: 0.008-0.016%; P: ≤0.017%; S: ≤0.005%; Ca: 0.0008-0.0020%; Als: 0.020-0.035%; O: ≤0.0035%; N: ≤0.0052%; and the rest is iron and inevitable impurities. The application aims to provide a production method of a yield strength 355MPa grade wind power tower structure steel plate with a thickness of 8-60mm, high production efficiency and stability, excellent mechanical properties, good plate shape and surface quality.

Description

Technical Field

[0001] This invention belongs to the field of hot rolling technology, and in particular relates to a production method of Q355ME wind power steel. Background Technology

[0002] Currently, addressing climate change, environmental change, and energy security have become global concerns. Wind energy, as a clean energy source, has a very broad application prospect. Against the backdrop of actively promoting energy structure transformation and vigorously developing the wind power industry, wind power equipment is developing towards larger scale, higher performance, and higher reliability. As a key material for critical structural components such as wind turbine towers, the demand for wind turbine steel plates continues to grow rapidly, placing higher demands on product quality and production efficiency.

[0003] New high-strength structural steels, represented by Q355 steel, are widely used in the production and construction of power grid towers. Effectively increasing the output per unit time of Q355 grade wind power steel while ensuring the steel plate's shape, surface quality, and mechanical properties is a significant challenge for steel companies. The traditional cold-loading process after casting not only consumes large amounts of energy, such as gas, during reheating, occupying valuable heating furnaces and intermediate storage areas, but also leads to extended production cycles and increased costs, becoming a bottleneck restricting capacity release and rapid response to market demands.

[0004] Patent CN 118880166 A, entitled "A Q355NE Normalized Rolled Wind Turbine Tower Steel Plate and Manufacturing Method Thereof," provides a method for producing Q355NE normalized rolled wind turbine tower steel plates. This method uses a 250mm thick cast billet, a normalizing rolling process, and a hot charging and hot delivery process. The billet quenching start temperature is 680-700℃, the slab quenching time is 120s, the slab furnace entry temperature is below 650℃, and the slab hardened layer depth is greater than 20mm. Compared to this patent, the biggest difference lies in the composition design. It uses a 250mm or 300mm thick cast billet, and the rolling process employs controlled rolling and controlled cooling. It specifies in detail the water flow requirements of the upper and lower spray beams of the billet quenching machine, the upper and lower water flow ratio, the water column height of the lower spray beam, the continuous casting billet transfer speed within the quenching machine, and the billet quenching time, among other key process parameters. Furthermore, the billet quenching time is adjusted to 120s-140s depending on the billet thickness.

[0005] Patent CN 116426823 A, entitled "A Thick-Dimensional High-Toughness Normalized Q355 Grade Wind Power Steel Plate and its Manufacturing Method," provides a method for producing thick-dimensional high-toughness normalized Q355 grade wind power steel plates. This method primarily focuses on controlling carbon equivalent, employing a reasonable rolling process, and optimizing the normalizing process to develop a thick-dimensional high-toughness normalized Q355 grade wind power steel plate. This patent mainly utilizes a direct-loading process for cast billets, eliminating the slow cooling process and shortening the production cycle. Simultaneously, the temperature of the directly loaded billets is significantly higher than that of the cold-loaded billets, reducing furnace heating energy consumption, thereby improving production efficiency and lowering production costs.

[0006] Patent CN 119020666 A, entitled "A Low-Cost Method for Producing Q420ME Wind Power Steel," provides a low-cost method for producing Q420ME wind power steel. This method uses a 250mm thick cast billet, a thermomechanical rolling process, and a hot charging and hot conveying process. The surface quenching and cooling time of the slab is designed to be controlled between 180s and 250s, with a slow cooling time ≤ 250min. This patent uses a 250mm or 300mm thick cast billet, a normalizing rolling process, and a hot charging and hot conveying process. It specifies in detail the water flow requirements of the upper and lower spray beams of the quenching machine, the upper and lower water flow ratio, the water column height of the lower spray beam, the continuous casting billet conveying speed within the quenching machine, and the quenching time of the cast billet, among other key process parameters. Furthermore, the quenching time of the cast billet is shortened to 120s-140s. Summary of the Invention

[0007] The purpose of this invention is to provide a method for producing structural steel plates for wind power towers with a yield strength of 355MPa, characterized by a thickness of 8-60mm, high efficiency and stability, excellent mechanical properties, good plate shape and surface quality.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0009] This invention discloses a method for producing Q355ME wind power steel, comprising:

[0010] 1) To ensure a certain compression ratio and slab quality, a continuous casting slab with a thickness of 250mm or 300mm is selected, and the center segregation of the slab is not greater than B1.0;

[0011] 2) Molten steel is treated in an RH furnace for at least 17 minutes under a vacuum not exceeding 112 Pa; 3) The thickness of the continuously cast billet is 250 mm or 30 mm. The superheat during casting is controlled at 15–28℃, and the casting speed is 0.9–1.1 m / min. Electromagnetic stirring and light reduction are used during continuous casting. The light reduction is applied to the third or fourth stage before the solidification endpoint, with a total reduction of 8.0 mm. Electromagnetic stirring is used in stages 4 and 5, with a frequency of 5 Hz and a current of 380 A. The water flow rate on the wide side of the crystallizer is 4500 L / min, and the water flow rate on the narrow side is 370 L / min. For the crystallizer, the inlet water temperature should be controlled at 36±2℃, the secondary cooling water temperature at 38±1℃, and the water quality indicators should meet the process requirements. Protective casting should be adopted, with the long nozzle sealing argon pressure controlled at ≥0.3MPa and the flow rate controlled at 130~160L / min. The tundish immersion nozzle sealing argon pressure should be 0.2MPa and the flow rate 15~20L / min. The billet straightening temperature should be controlled at 950~1000℃, and the temperature difference along the width of the billet should not exceed 50℃. Protective casting should be carried out to prevent secondary oxidation of molten steel and nitrogen absorption.

[0012] 4) Slab Quenching Process: 250mm or 300mm thick continuously cast slabs are used for production. The slabs are charged directly into the heating furnace without being removed from the production line and undergoing slow cooling. To eliminate hot-charging cracks on the surface of the rolled steel plate and ensure the uniformity of the finished steel plate's properties, the continuously cast slabs must undergo a quenching process. To avoid large temperature differences between the upper and lower parts of the continuously cast slab, the quenching process requires an upper spray beam flow rate ≥ 75m³ / h. 3 / h, the flow rate of the lower spray beam is ≥150m³ / h. 3 / h, water flow ratio between upper and lower water is 2:1, water column height of lower spray beam is greater than 315mm; continuous casting billet transfer speed in quenching machine is 0.1m / s, quenching time for 250mm thick billet is 120s, quenching time for 300mm thick billet is 140s.

[0013] 5) Heating process: The surface temperature of the slab entering the furnace shall not exceed 650℃. A walking beam furnace shall be used for heating the slab. The temperature of the continuously cast slab exiting the furnace shall be 1150~1250℃, and the heating time shall be 220~260 minutes. The heating time of the slab in the soaking zone shall not be less than 30 minutes. When the slab is heated in the furnace, the moving speed of the movable beam supporting the slab shall be 1.10m / min.

[0014] 6) Steel plate rolling forming process: After the slab is heated, controlled rolling is performed. The initial rolling thickness in the first stage is the slab thickness, the initial rolling temperature is 1130~1220℃, the final rolling temperature in the first stage is ≥1050℃, the single-pass reduction rate during the high-temperature extension rolling in the first stage is ≥12%, the rolling speed in the first stage is 1.7~3.1m / s, and the torque set during the first stage rolling is 2150kN·m. The initial rolling thickness in the second stage is 3 times the finished steel plate thickness, and the initial rolling temperature in the second stage is 870~90kN·m. The rolling temperature in the second stage is 10℃, and the final rolling temperature in the second stage is 790~830℃; the rolling speed in the second stage is 3.5~4.5m / s, the torque set during the second stage rolling is 2280kN·m, and the final reduction rate in the second stage is ≥5.5%; after the steel plate is rolled, it is subjected to laminar flow cooling, the ACC water temperature is 17~19℃, the cooling rate is 8~12℃ / s, the final cooling temperature is 615~665℃, the ACC roller speed is 1.70~1.90m / s, and the cooling water flow ratio between the lower and upper spray beams of the ACC is 2.00;

[0015] The chemical composition of the Q355ME wind power steel, by weight percentage, includes: C: 0.065–0.085%; Si: 0.3–0.4%; Mn: 1.4–1.5%; Nb: 0.025–0.035%; Ti: 0.008–0.016%; P≤0.017%; S≤0.005%; Ca: 0.0008–0.0020%; Als: 0.020–0.035%; O: ≤0.0035%; N: ≤0.0052%; the remainder being iron and unavoidable impurities.

[0016] The Q355ME wind power steel has a yield strength between 385 and 485 MPa, a tensile strength between 521 and 594 MPa, an elongation between 21 and 27%, and an impact energy at -40℃ between 245 and 335 J.

[0017] Furthermore, the thickness of the Q355ME wind power steel plate is 8mm to 60mm.

[0018] Furthermore, the chemical composition of the Q355ME wind power steel is as follows (mass percentage): C 0.07%, Si 0.36%, Mn 1.43%, P 0.014%, S 0.002%, Als 0.030%, Nb 0.029%, Ca 0.0005%, H 0.6 ppm; O 0.0032%; N 0.0040%; the balance being Fe and unavoidable impurities.

[0019] Furthermore, the billet thickness is 250mm, and the flow rate of the spray beam on the quenching machine is 77m³ / h. 3 / h, flow rate of the lower spray beam is 150m³ / h. 3The quenching time is 120 seconds. After quenching, the billet is placed in a heating furnace and heated for 180 minutes, followed by a soaking time of 35 minutes.

[0020] Furthermore, the chemical composition of the Q355ME wind power steel is as follows (mass percentage): C 0.07%, Si 0.33%, Mn 1.44%, P 0.013%, S 0.002%, Als 0.026%, Nb 0.029%, Ca 0.0007%, H 0.6 ppm; O 0.0032%; N 0.0040%; the balance being Fe and unavoidable impurities.

[0021] Furthermore, the billet thickness is 300mm, and the flow rate of the spray beam on the quenching machine is 78m³ / h. 3 / h, the flow rate of the lower spray beam is 152m³ / h. 3 The quenching time is 140s, and after quenching, the billet is placed in the heating furnace for 208 minutes, with a high-temperature time of 134 minutes.

[0022] Furthermore, the chemical composition of the Q355ME wind power steel is as follows (mass percentage): C 0.08%, Si 0.34%, Mn 1.45%, P 0.013%, S 0.002%, Als 0.027%, Nb 0.029%, Ca 0.0001%, H 0.6 ppm; O 0.0032%; N 0.0040%; the balance being Fe and unavoidable impurities.

[0023] Furthermore, the billet thickness is 300mm, and the flow rate of the spray beam on the quenching machine is 77m³ / h. 3 / h, flow rate of the lower spray beam 15 4 m3 / h, quenching time 140s, after quenching the billet is placed in the heating furnace, the heating time is 210 minutes, the high temperature time is 135 minutes.

[0024] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0025] The steel plate thickness described in this invention ranges from 8mm to 60mm. The wind power steel slab with a yield strength of 355MPa is heated at a higher temperature. This ensures that alloying elements are fully dissolved during heating, allowing for the precipitate of microalloyed carbides and nitrides during subsequent rolling and cooling, thus improving the steel plate's microstructure. The higher heating temperature also facilitates the removal of the iron oxide scale formed during heating, which is beneficial for controlling the surface quality of the steel plate. The longer soaking time ensures a more uniform slab exit temperature, resulting in a more uniform steel plate structure and properties.

[0026] The heated continuously cast billets are subjected to controlled rolling in both the austenite recrystallization and non-recrystallization zones. This steel grade employs a two-stage controlled rolling process. The first stage, austenite recrystallization controlled rolling in the high-temperature zone, utilizes a low-speed, high-reduction rolling strategy. The large single-pass reduction rate allows the rolling deformation to fully penetrate to the center of the steel plate, effectively refining the austenite grains and homogenizing the austenite microstructure. Simultaneously, the high-temperature welding effect generated during rolling largely eliminates defects such as porosity and microcracks within the cast billet, increasing the density of the steel plate and improving the overall material properties. During the first stage of rolling, due to the billet's thickness and slow temperature drop, the low-speed rolling ensures a significant temperature decrease after each pass. This allows for varying degrees of grain refinement with each pass, ultimately achieving the goal of fully refining the austenite grains.

[0027] After the first stage of rolling, the intermediate billet is oscillated on the roller table to cool down. Rolling begins when it reaches the second stage starting temperature, which is a low-temperature, non-recrystallization controlled rolling process. Through multiple rolling passes and a large cumulative reduction, a significant amount of deformation energy and phase deformation nucleation sites accumulate within the grains. The rolled steel sheet undergoes rapid ACC cooling. This rapid cooling to a lower temperature allows the steel sheet to complete the γ-phase → α-phase transformation at a lower temperature, resulting in a fine-grained α-phase microstructure, thus giving the steel sheet good toughness.

[0028] 1) This invention adopts a low-composition design, using only inexpensive alloys such as Si, Mn, and Nb. Through appropriate smelting, continuous casting, heating, controlled rolling, and controlled cooling processes, it produces wind power steel with a yield strength of 355MPa and excellent comprehensive performance. Through precise control of the online quenching process of the billet, it effectively eliminates hot-fix cracks on the surface of the rolled steel plate, ensures the uniformity of the finished steel plate performance, improves rolling efficiency, reduces billet heating time, and reduces billet heating energy consumption.

[0029] 2) The steel plate has good strength, plasticity, and toughness, and its microstructure consists of fine ferrite, pearlite, and a small amount of bainite. The yield strength of the steel plate is between 385 and 485 MPa, the tensile strength is between 521 and 594 MPa, the elongation is between 21 and 27%, and the impact energy at -40℃ is between 245 and 335 J. Attached Figure Description

[0030] Figure 1 Image of the microstructure of a 300mm Q355ME billet after cooling for 140 seconds, at a position 21mm from the top surface (microstructure is M+ with a small amount of B).

[0031] Figure 2 Image of the microstructure of a 300mm Q355ME billet, taken 26mm from the top surface after 140s of cooling (microstructure consists of low F, B, and P).

[0032] Figure 3Image of the microstructure of a 300mm Q355ME billet after cooling for 140s, at a position 12mm from the lower surface (microstructure is F+P).

[0033] Figure 4 Image of the microstructure of a Q355ME 300mm billet, taken 15mm from the lower surface after 140s of cooling (microstructure consists of low F, B, and P). Detailed Implementation

[0034] The present invention will be further described below with reference to embodiments.

[0035] Example 1

[0036] The slabs to be rolled after smelting and continuous casting enter the quenching machine. The slab thickness is 250mm, and the flow rate of the spray beam on the quenching machine is 77m³ / h. 3 / h, flow rate of the lower spray beam is 150m³ / h. 3 The quenching time is 120s, and after quenching, the billet is placed in a heating furnace for 180 minutes, followed by a soaking time of 35 minutes. The chemical composition of the billet (mass percentage) is as follows: C 0.07%, Si 0.36%, Mn 1.43%, P 0.014%, S 0.002%, Als 0.030%, Nb 0.029%, Ca 0.0005%, H 0.6 ppm; O 0.0032%; N 0.0040%; the balance being Fe and unavoidable impurities. The billet is rolled into a 20mm thick steel plate. Detailed rolling processes are shown in Table 1, and its mechanical properties are shown in Table 2.

[0037] Example 2

[0038] The slabs to be rolled after smelting and continuous casting enter the quenching machine. The slab thickness is 300mm, and the flow rate of the spray beam on the quenching machine is 78m³. 3 / h, the flow rate of the lower spray beam is 152m³ / h. 3 The quenching time was 140s, and after quenching, the billet was placed in a heating furnace for 208 minutes, with a high-temperature time of 134 minutes. The chemical composition of the billet (mass percentage) was: C 0.07%, Si 0.33%, Mn 1.44%, P 0.013%, S 0.002%, Als 0.026%, Nb 0.029%, Ca 0.0007%, H 0.6 ppm; O 0.0032%; N 0.0040%; the balance being Fe and unavoidable impurities. The billet was rolled into a 40mm thick steel plate. Detailed rolling processes are shown in Table 1, and its mechanical properties are shown in Table 2.

[0039] Example 3

[0040] The slabs to be rolled after smelting and continuous casting enter the quenching machine. The slab thickness is 300mm, and the flow rate of the spray beam on the quenching machine is 77m³ / h.3 / h, the flow rate of the lower spray beam is 154m³ / h. 3 The quenching time was 140s, and after quenching, the billet was placed in a heating furnace for 210 minutes, with a high-temperature time of 135 minutes. The chemical composition of the billet (mass percentage) was: C 0.08%, Si 0.34%, Mn 1.45%, P 0.013%, S 0.002%, Als 0.027%, Nb 0.029%, Ca 0.0001%, H 0.6 ppm; O 0.0032%; N 0.0040%; the balance being Fe and unavoidable impurities. The billet was rolled into a steel plate with a thickness of 80mm. Detailed rolling process information is shown in Table 1, and its mechanical properties are shown in Table 2.

[0041] Table 1. Process parameters for Examples 1-3

[0042]

[0043] Table 2 Mechanical properties of Examples 1-4

[0044]

[0045] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for producing Q355ME wind power steel, characterized in that, include: 1) To ensure a certain compression ratio and slab quality, a continuous casting slab with a thickness of 250mm or 300mm is selected, and the center segregation of the slab is not greater than B1.0; 2) Molten steel is treated in an RH furnace for at least 17 minutes under a vacuum not exceeding 112 Pa; 3) The thickness of the continuously cast billet is 250 mm or 30 mm. The superheat during casting is controlled at 15–28℃, and the casting speed is 0.9–1.1 m / min. Electromagnetic stirring and light reduction are used during continuous casting. The light reduction is applied to the third or fourth stage before the solidification endpoint, with a total reduction of 8.0 mm. Electromagnetic stirring is used in stages 4 and 5, with a frequency of 5 Hz and a current of 380 A. The water flow rate on the wide side of the crystallizer is 4500 L / min, and the water flow rate on the narrow side is 370 L / min. For the crystallizer, the inlet water temperature should be controlled at 36±2℃, the secondary cooling water temperature at 38±1℃, and the water quality indicators should meet the process requirements. Protective casting should be adopted, with the long nozzle sealing argon pressure controlled at ≥0.3MPa and the flow rate controlled at 130~160L / min. The tundish immersion nozzle sealing argon pressure should be 0.2MPa and the flow rate 15~20L / min. The billet straightening temperature should be controlled at 950~1000℃, and the temperature difference along the width of the billet should not exceed 50℃. Protective casting should be carried out to prevent secondary oxidation of molten steel and nitrogen absorption. 4) Slab Quenching Process: 250mm or 300mm thick continuously cast slabs are used for production. The slabs are charged directly into the heating furnace without being removed from the production line and undergoing slow cooling. To eliminate hot-charging cracks on the surface of the rolled steel plate and ensure the uniformity of the finished steel plate's properties, the continuously cast slabs must undergo a quenching process. To avoid large temperature differences between the upper and lower parts of the continuously cast slab, the quenching process requires an upper spray beam flow rate ≥ 75m³ / h. 3 / h, the flow rate of the lower spray beam is ≥150m³ / h. 3 / h, water flow ratio between upper and lower water is 2:1, water column height of lower spray beam is greater than 315mm; continuous casting billet transfer speed in quenching machine is 0.1m / s, quenching time for 250mm thick billet is 120s, quenching time for 300mm thick billet is 140s. 5) Heating process: The surface temperature of the slab entering the furnace shall not exceed 650℃. A walking beam furnace shall be used for heating the slab. The temperature of the continuously cast slab exiting the furnace shall be 1150~1250℃, and the heating time shall be 220~260 minutes. The heating time of the slab in the soaking zone shall not be less than 30 minutes. When the slab is heated in the furnace, the moving speed of the movable beam supporting the slab shall be 1.10m / min. 6) Steel plate rolling forming process: After the slab is heated, controlled rolling is performed. The initial rolling thickness in the first stage is the slab thickness, the initial rolling temperature is 1130~1220℃, the final rolling temperature in the first stage is ≥1050℃, the single-pass reduction rate during the high-temperature extension rolling in the first stage is ≥12%, the rolling speed in the first stage is 1.7~3.1m / s, and the torque set during the first stage rolling is 2150kN·m. The initial rolling thickness in the second stage is 3 times the finished steel plate thickness, and the initial rolling temperature in the second stage is 870~90kN·m. The rolling temperature in the second stage is 10℃, and the final rolling temperature in the second stage is 790~830℃; the rolling speed in the second stage is 3.5~4.5m / s, the torque set during the second stage rolling is 2280kN·m, and the final reduction rate in the second stage is ≥5.5%; after the steel plate is rolled, it is subjected to laminar flow cooling, the ACC water temperature is 17~19℃, the cooling rate is 8~12℃ / s, the final cooling temperature is 615~665℃, the ACC roller speed is 1.70~1.90m / s, and the cooling water flow ratio between the lower and upper spray beams of the ACC is 2.00; The chemical composition of the Q355ME wind power steel, by weight percentage, includes: C: 0.065–0.085%; Si: 0.3–0.4%; Mn: 1.4–1.5%; Nb: 0.025–0.035%; Ti: 0.008–0.016%; P≤0.017%; S≤0.005%; Ca: 0.0008–0.0020%; Als: 0.020–0.035%; O: ≤0.0035%; N: ≤0.0052%; the remainder being iron and unavoidable impurities. The Q355ME wind power steel has a yield strength between 385 and 485 MPa, a tensile strength between 521 and 594 MPa, an elongation between 21 and 27%, and an impact energy at -40℃ between 245 and 335 J.

2. The production method of Q355ME wind power steel according to claim 1, characterized in that, The thickness of the Q355ME wind power steel plate is 8mm to 60mm.

3. The production method of Q355ME wind power steel according to claim 1, characterized in that, The chemical composition of the Q355ME wind power steel is as follows (mass percentage): C 0.07%, Si 0.36%, Mn 1.43%, P 0.014%, S 0.002%, Als 0.030%, Nb 0.029%, Ca 0.0005%, H 0.6 ppm; O 0.0032%; N 0.0040%; the balance being Fe and unavoidable impurities.

4. The method for producing Q355ME wind power steel according to claim 3, characterized in that, The billet thickness is 250mm, and the flow rate of the spray beam on the quenching machine is 77m³ / h. 3 / h, flow rate of the lower spray beam is 150m³ / h. 3 The quenching time is 120 seconds. After quenching, the billet is placed in a heating furnace and heated for 180 minutes, followed by a soaking time of 35 minutes.

5. The method for producing Q355ME wind power steel according to claim 1, characterized in that, The chemical composition of the Q355ME wind power steel is as follows (mass percentage): C 0.07%, Si 0.33%, Mn 1.44%, P 0.013%, S 0.002%, Als 0.026%, Nb 0.029%, Ca 0.0007%, H 0.6 ppm; O 0.0032%; N 0.0040%; the balance being Fe and unavoidable impurities.

6. The method for producing Q355ME wind power steel according to claim 5, characterized in that, The billet thickness is 300mm, and the flow rate of the spray beam on the quenching machine is 78m³. 3 / h, the flow rate of the lower spray beam is 152m³ / h. 3 The quenching time is 140s, and after quenching, the billet is placed in the heating furnace for 208 minutes, with a high-temperature time of 134 minutes.

7. The method for producing Q355ME wind power steel according to claim 1, characterized in that, The chemical composition of the Q355ME wind power steel is as follows (mass percentage): C 0.08%, Si 0.34%, Mn 1.45%, P 0.013%, S 0.002%, Als 0.027%, Nb 0.029%, Ca 0.0001%, H 0.6 ppm; O 0.0032%; N 0.0040%; the balance being Fe and unavoidable impurities.

8. The method for producing Q355ME wind power steel according to claim 7, characterized in that, The billet thickness is 300mm, and the flow rate of the spray beam on the quenching machine is 77m³ / h. 3 / h, flow rate of the lower spray beam 15 4 m3 / h, quenching time 140s, after quenching the billet is placed in the heating furnace, the heating time is 210 minutes, the high temperature time is 135 minutes.

Images