A component control method for improving machining precision of 20crmnTi steel gear

Abstract

The present application relates to the technical field of metallurgy, and discloses a component control method for improving machining precision of 20CrMnTi steel gear, which comprises the following steps: step 1, molten iron pretreatment; step 2, converter smelting; step 3, LF refining; step 4, vacuum degassing; step 5, continuous casting; and step 6, finished product component closed-loop detection. In the molten iron pretreatment, desulfurization is carried out by spraying, and the operation of fully removing slag is carried out, so that the sulfur content is controlled to be less than or equal to 0.016wt%, the phosphorus content is controlled to be less than or equal to 0.024wt%, the degree of segregation of harmful elements at the grain boundary is reduced, the machining deformation caused by abnormal structure is reduced, and the foundation for subsequent machining precision control of steel is laid. In the converter smelting, the raw materials are controlled according to the molten iron ratio, the iron ore is added in batches, the end point temperature and the carbon content are accurately controlled, the slag blocking tapping operation is cooperated, the basic component interval is stabilized, the foreign impurities and the slag involved are reduced, and the initial component fluctuation range is reduced, so that the stable molten steel conditions for subsequent refining and precise alloying are provided.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, specifically to a composition control method for improving the machining accuracy of 20CrMnTi steel gears. Background Technology

[0002] Chromium-manganese-titanium steel for gears is mostly used in precision parts such as gears and gear shafts in automotive steering systems. It requires multiple machining and carburizing heat treatment processes. The uniformity and purity of the steel composition directly determine the machining accuracy and dimensional stability of the parts.

[0003] In actual mass production, conventional composition control processes have significant shortcomings: hot metal pretreatment only involves simple desulfurization, resulting in high levels of residual sulfur and phosphorus; the composition and temperature fluctuations at the converter smelting endpoint are large, and slag is easily drawn into the ladle; the timing of alloy addition in LF refining is chaotic, soft blowing time is insufficient, and inclusion removal is inadequate; the duration and degree of vacuum degassing are not adequately controlled, resulting in high levels of hydrogen, oxygen, nitrogen, and residual harmful elements in the steel; and the continuous casting process lacks protective casting and homogenization control, leading to significant segregation of cross-sectional composition.

[0004] These problems can lead to excessive mixed crystal and banded structures during steel carburizing, excessive bending deformation of parts after machining and heat treatment, fluctuations in hardenability exceeding the standard range, and the inability of the tooth profile and dimensional accuracy of the machined gears to meet the high-precision assembly requirements of passenger car and commercial vehicle steering systems. Some batches can only be downgraded for use due to substandard accuracy. Summary of the Invention

[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a composition control method for improving the machining accuracy of 20CrMnTi steel gears. This method has advantages such as reducing the segregation of harmful elements at grain boundaries and reducing machining deformation caused by abnormal structures. It solves the problems of mixed crystals and excessive banded structures during steel carburizing, and the bending deformation of parts exceeding the allowable range after machining and heat treatment.

[0006] (II) Technical Solution To achieve the above-mentioned goal of reducing the segregation of harmful elements at grain boundaries and reducing processing deformation caused by abnormal structure, the present invention provides the following technical solution: a composition control method for improving the processing accuracy of 20CrMnTi steel gears, comprising step 1: hot metal pretreatment, step 2: converter smelting, step 3: LF refining, step 4: vacuum degassing, step 5: continuous casting, and step 6: closed-loop detection of finished product composition, wherein step 1: hot metal pretreatment; The molten iron from the blast furnace is introduced into a desulfurization treatment tank, and a magnesium-based composite desulfurizing agent is injected into the molten iron. The injection pressure is controlled at 0.3~0.6MPa, and the mixture is stirred continuously for 8~15 minutes to allow the desulfurizing agent to fully react with the molten iron. After stirring, let it stand for 5-8 minutes, then use a slag remover to thoroughly clean the slag on the surface of the molten iron until there is no exposed slag layer. The composition of molten iron was sampled and tested, and the sulfur content was controlled at ≤0.016wt% and the phosphorus content at ≤0.024wt% to reduce the impact of harmful elements on the precision of subsequent processing. Recording the temperature and initial composition data of molten iron provides a basis for the control of converter composition.

[0007] Preferably, step 2 involves converter smelting; Raw materials are prepared according to a ratio of ≥800 kg / t of molten iron consumption. Rust and impurities on the surface of scrap steel are cleaned in advance, the proportion of scrap steel added is controlled, and interference from external elements is reduced. The smelting process adopts a top and bottom blowing process. During the blowing process, iron ore is added in 2 to 3 batches, with each batch containing 400 to 900 kg, to help adjust the carbon content and the cleanliness of the molten steel. Precise temperature control is performed at the end of the blowing process, with the final temperature controlled at 1600~1650℃ and the final carbon content controlled at 0.05~0.12wt%, to avoid compositional deviation caused by overblowing; The slag-blocking device is activated simultaneously during tapping, and the tapping time is controlled within 3 to 6 minutes to prevent slag from entering the ladle and affecting the purity of the composition.

[0008] Preferably, step 3: LF refining; After the ladle is placed in place, lime and pre-melted slag are added to form slag. The temperature is raised by electricity for 3-7 minutes. After the slag melts, the basicity is adjusted to 3.0-5.8, and the FeO content in the slag is kept ≤1.0wt% to form a stable and purified slag system. Add the alloys in the following order: carbon → silicon → manganese → chromium → titanium → aluminum. Stir with argon gas for 3-5 minutes after each alloy is added, with the flow rate controlled at 40-80 L / min.

[0009] 4. Preferably, step 3: LF refining; Adjust the carbon content to 0.17~0.24wt% to ensure the matching of gear carburization and strength; Adjust the silicon content to 0.16~0.38wt% to optimize the deoxidation effect of steel; Adjust the manganese content to 0.78~1.12wt% to stabilize the hardenability of the steel; Adjust the chromium content to 0.98~1.32wt% to control the amount of deformation during heat treatment; Adjust the titanium content to 0.038~0.105wt% to fix free nitrogen in the steel and suppress mixed crystals; Adjust the acid-soluble aluminum content to 0.014~0.042wt% to refine the austenite grains; Pure calcium wire is fed in at a uniform rate at the end of refining, with a feeding speed of 140~210m / min and a feeding amount of 130~170m / furnace, resulting in brittle inclusions in the modified steel. After the wire is fed, gently blow argon gas for ≥16 minutes at a flow rate of 20~50 L / min to promote the full floating of inclusions.

[0010] Preferably, step 4 involves vacuum degassing. The ladle is moved into the vacuum treatment station and evacuated to a vacuum level of ≤1mbar. The vacuum is maintained for 12~18min to remove hydrogen and nitrogen gases from the steel. During vacuum treatment, maintain weak argon gas stirring at a flow rate of 20-40 L / min, so that the auxiliary gas and small inclusions float to the surface. After the air is broken, samples are taken for testing, and the total oxygen content is controlled to be ≤16ppm and the nitrogen content is ≤55ppm. Control the content of residual elements: arsenic ≤ 0.016 wt%, tin ≤ 0.011 wt%, lead ≤ 0.011 wt%, antimony ≤ 0.011 wt%, bismuth ≤ 0.011 wt%, to reduce the risk of carburizing and crystal mixing and processing deformation.

[0011] Preferably, step 5 involves continuous casting. The process involves full-process protective casting, with a 30-50mm thick layer of covering agent and carbonized rice husks spread on the tundish to prevent the molten steel from being exposed and oxidized. The superheat of the tundish is controlled at 20~40℃, and the liquid level is stable at ≥600mm to reduce the tendency of component segregation. The continuous casting speed is controlled at 0.75~0.95m / min, and combined with the crystallizer and end electromagnetic stirring, dendrite segregation is weakened; Samples of molten steel from the tundish were taken periodically to detect fluctuations in carbon, manganese, and chromium levels, with the cross-sectional composition range controlled to be ≤0.012wt%. Unstable billets are cut and removed separately during the initial casting and re-casting stages to ensure the consistency of the finished product composition.

[0012] Preferably, step 6 involves closed-loop detection of the finished product components. Steel samples were taken from each heat for full element analysis, covering the main alloy, harmful elements, residual elements and gas content; Simultaneous detection of non-metallic inclusions, austenite grain size, and banded structure indicators: coarse inclusions (Class B) ≤ 1.5 grade, grain size ≥ 6 grade, and banded structure ≤ 2.5 grade; According to the internal control composition range, if the batch is unqualified, the process parameters should be adjusted and the batch should not proceed to the subsequent rolling process; Record the composition data throughout the entire process, and continuously optimize parameters based on processing accuracy feedback to form a closed loop for quality control.

[0013] (III) Beneficial Effects Compared with the prior art, the present invention provides a composition control method for improving the machining accuracy of 20CrMnTi steel gears, which has the following beneficial effects: 1. The composition control method for improving the machining accuracy of 20CrMnTi steel gears involves controlling the sulfur content to ≤0.016wt% and the phosphorus content to ≤0.024wt% through hot metal pretreatment by blowing desulfurization and thorough slag removal. This reduces the degree of segregation of harmful elements at grain boundaries and minimizes machining deformation caused by abnormal microstructure, laying the foundation for subsequent precision control of the steel.

[0014] 2. The composition control method for improving the machining accuracy of 20CrMnTi steel gears involves controlling raw materials according to the iron-to-metal ratio during converter smelting, adding iron ore in batches, and precisely controlling the final temperature and carbon content. Combined with slag-blocking tapping operations, this stabilizes the basic composition range, reduces the incorporation of foreign impurities and slag, and minimizes the fluctuation range of the initial composition, thus providing stable steel conditions for subsequent refining and precise alloying.

[0015] 3. The composition control method for improving the machining accuracy of 20CrMnTi steel gears. This method stabilizes the main alloying elements within the target range by adjusting the slag basicity and FeO content, sequential step-by-step alloying, precise calcium feeding treatment, and soft blowing operation for ≥16min during LF refining. This not only refines the austenite grains but also modifies brittle inclusions and promotes their flotation, improves the uniformity of the steel structure, and reduces the probability of mixed crystals occurring during carburizing.

[0016] 4. The composition control method for improving the machining accuracy of 20CrMnTi steel gears involves vacuum degassing at a vacuum level of ≤1mbar for 12~18min, combined with weak argon stirring, to control the total oxygen content to ≤16ppm and the nitrogen content to ≤55ppm. At the same time, the content of residual elements such as arsenic, tin, lead, antimony and bismuth is controlled to reduce the structural defects caused by gases and residual elements, reduce the amount of deformation of parts during heat treatment, and improve dimensional stability.

[0017] 5. The composition control method for improving the machining accuracy of 20CrMnTi steel gears: This method adopts full-process protective casting, controls the superheat of the tundish and the casting speed, and cooperates with the crystallizer and end electromagnetic stirring to control the cross-sectional composition range within ≤0.012wt%, weaken dendrite segregation, improve the uniformity of steel cross-sectional composition, stabilize the hardenability fluctuation range, and avoid machining accuracy differences caused by composition segregation.

[0018] 6. The composition control method for improving the machining accuracy of 20CrMnTi steel gears. This method involves closed-loop testing of finished products, which includes full elemental analysis, inclusion, grain size and banded structure detection. This forms a closed-loop control system for the entire process of composition and structure, ensuring that all indicators of the steel meet the requirements of precision machining, improving the accuracy pass rate of gear machining and carburizing, and adapting to the assembly and use requirements of high-precision gears. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] This solution provides a technical solution, specifically, a composition control method for improving the machining accuracy of 20CrMnTi steel gears, including the following steps: Step 1: Hot metal pretreatment (pre-control of harmful elements). The molten iron from the blast furnace is introduced into a desulfurization treatment tank, and a magnesium-based composite desulfurizing agent is injected into the molten iron. The injection pressure is controlled at 0.3~0.6MPa, and the mixture is stirred continuously for 8~15 minutes to allow the desulfurizing agent to fully react with the molten iron. After stirring, let it stand for 5-8 minutes, then use a slag remover to thoroughly clean the slag on the surface of the molten iron until there is no exposed slag layer. The composition of molten iron was sampled and tested, and the sulfur content was controlled at ≤0.016wt% and the phosphorus content at ≤0.024wt% to reduce the impact of harmful elements on the precision of subsequent processing. Recording the temperature and initial composition data of molten iron provides a basic basis for converter composition control; Step 2: Converter smelting (rough adjustment of basic components); Raw materials are prepared according to a ratio of ≥800 kg / t of molten iron consumption. Rust and impurities on the surface of scrap steel are cleaned in advance, the proportion of scrap steel added is controlled, and interference from external elements is reduced. The smelting process adopts a top and bottom blowing process. During the blowing process, iron ore is added in 2 to 3 batches, with each batch containing 400 to 900 kg, to help adjust the carbon content and the cleanliness of the molten steel. Precise temperature control is performed at the end of the blowing process, with the final temperature controlled at 1600~1650℃ and the final carbon content controlled at 0.05~0.12wt%, to avoid compositional deviation caused by overblowing; The slag-blocking device is activated simultaneously during tapping, and the tapping time is controlled within 3 to 6 minutes to prevent slag from entering the ladle and affecting the purity of the composition. Step 3: LF Refining (Precision Alloying and Composition Control); After the ladle is placed in place, lime and pre-melted slag are added to form slag. The temperature is raised by electricity for 3-7 minutes. After the slag melts, the basicity is adjusted to 3.0-5.8, and the FeO content in the slag is kept ≤1.0wt% to form a stable and purified slag system. Add the alloys in the following order: carbon → silicon → manganese → chromium → titanium → aluminum. After each alloy is added, stir with argon gas for 3-5 minutes, controlling the flow rate at 40-80 L / min. Adjust the carbon content to 0.17~0.24wt% to ensure the matching of gear carburization and strength; Adjust the silicon content to 0.16~0.38wt% to optimize the deoxidation effect of steel; Adjust the manganese content to 0.78~1.12wt% to stabilize the hardenability of the steel; Adjust the chromium content to 0.98~1.32wt% to control the amount of deformation during heat treatment; Adjust the titanium content to 0.038~0.105wt% to fix free nitrogen in the steel and suppress mixed crystals; Adjust the acid-soluble aluminum content to 0.014~0.042wt% to refine the austenite grains; Pure calcium wire is fed in at a uniform rate at the end of refining, with a feeding speed of 140~210m / min and a feeding amount of 130~170m / furnace, resulting in brittle inclusions in the modified steel. After feeding the wire, gently blow argon gas for ≥16 minutes at a flow rate of 20~50 L / min to promote the full floating of inclusions. Step 4: Vacuum degassing (purification of gases and residual elements); The ladle is moved into the vacuum treatment station and evacuated to a vacuum level of ≤1mbar. The vacuum is maintained for 12~18min to remove hydrogen and nitrogen gases from the steel. During vacuum treatment, maintain weak argon gas stirring at a flow rate of 20-40 L / min, so that the auxiliary gas and small inclusions float to the surface. After the air is broken, samples are taken for testing, and the total oxygen content is controlled to be ≤16ppm and the nitrogen content is ≤55ppm. Control the content of residual elements: arsenic ≤ 0.016 wt%, tin ≤ 0.011 wt%, lead ≤ 0.011 wt%, antimony ≤ 0.011 wt%, bismuth ≤ 0.011 wt%, to reduce the risk of carburizing mixed crystals and processing deformation; Step 5: Continuous casting (composition homogenization control); The process involves full-process protective casting, with a 30-50mm thick layer of covering agent and carbonized rice husks spread on the tundish to prevent the molten steel from being exposed and oxidized. The superheat of the tundish is controlled at 20~40℃, and the liquid level is stable at ≥600mm to reduce the tendency of component segregation. The continuous casting speed is controlled at 0.75~0.95m / min, and combined with the crystallizer and end electromagnetic stirring, dendrite segregation is weakened; Samples of molten steel from the tundish were taken periodically to detect fluctuations in carbon, manganese, and chromium levels, with the cross-sectional composition range controlled to be ≤0.012wt%. Unstable billets during the initial casting and re-casting stages are cut and removed separately to ensure the consistency of the finished product composition; Step 6: Closed-loop testing of finished product components; Steel samples were taken from each heat for full element analysis, covering the main alloy, harmful elements, residual elements and gas content; Simultaneous detection of non-metallic inclusions, austenite grain size, and banded structure indicators: coarse inclusions (Class B) ≤ 1.5 grade, grain size ≥ 6 grade, and banded structure ≤ 2.5 grade; According to the internal control composition range, if the batch is unqualified, the process parameters should be adjusted and the batch should not proceed to the subsequent rolling process; Record the composition data throughout the entire process, and continuously optimize parameters based on processing accuracy feedback to form a closed loop for quality control; Furthermore, this method controls the sulfur content to ≤0.016wt% and the phosphorus content to ≤0.024wt% through desulfurization by injection and thorough slag removal during the pretreatment of molten iron. This reduces the degree of segregation of harmful elements at the grain boundaries, reduces processing deformation caused by abnormal structure, and lays the foundation for precision control in subsequent steel processing. Furthermore, this method controls raw materials according to the iron ratio in converter smelting, adds iron ore in batches, and precisely controls the final temperature and carbon content. Combined with slag-blocking and steel tapping operations, it stabilizes the basic composition range, reduces the incorporation of foreign impurities and slag, and reduces the fluctuation range of the initial composition, thus providing stable steel conditions for subsequent refining and precise alloying. Furthermore, in LF refining, this method stabilizes the main alloying elements within the target range by controlling the slag basicity and FeO content, sequential step-by-step alloying, precise calcium feeding treatment, and soft blowing operation for ≥16min. This not only refines the austenite grains but also modifies brittle inclusions and promotes their flotation, improves the uniformity of the steel structure, and reduces the probability of mixed crystals occurring during carburizing. Furthermore, the method involves vacuum degassing at a vacuum level of ≤1mbar for 12~18min, combined with weak argon stirring, to control the total oxygen content to ≤16ppm and the nitrogen content to ≤55ppm. At the same time, the content of residual elements such as arsenic, tin, lead, antimony and bismuth is controlled to reduce the structural defects caused by gases and residual elements, reduce the amount of deformation of parts during heat treatment, and improve dimensional stability. Furthermore, this method employs full-process protective casting, controls the overheating of the tundish and the casting speed, and combines it with a crystallizer and end electromagnetic stirring to control the cross-sectional composition range within ≤0.012wt%, weaken dendrite segregation, improve the uniformity of the steel cross-section composition, stabilize the hardenability fluctuation range, and avoid differences in processing accuracy caused by composition segregation. Furthermore, this method enables closed-loop testing of finished products through full elemental analysis, inclusion, grain size and banded structure detection, forming a closed-loop control of composition and structure throughout the entire process. This ensures that all indicators of the steel meet the requirements of precision machining, improves the accuracy and pass rate of gear machining and carburizing, and adapts to the assembly and use requirements of high-precision gears.

[0021] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composition control method for improving the machining accuracy of 20CrMnTi steel gears, comprising steps 1: hot metal pretreatment, 2: converter smelting, 3: LF refining, 4: vacuum degassing, 5: continuous casting, and 6: closed-loop detection of finished product composition, characterized in that: Step 1: Hot metal pretreatment; The molten iron from the blast furnace is introduced into a desulfurization treatment tank, and a magnesium-based composite desulfurizing agent is injected into the molten iron. The injection pressure is controlled at 0.3~0.6MPa, and the mixture is stirred continuously for 8~15 minutes to allow the desulfurizing agent to fully react with the molten iron. After stirring, let it stand for 5-8 minutes, then use a slag remover to thoroughly clean the slag on the surface of the molten iron until there is no exposed slag layer. The composition of molten iron was sampled and tested, and the sulfur content was controlled at ≤0.016wt% and the phosphorus content at ≤0.024wt% to reduce the impact of harmful elements on the precision of subsequent processing. Recording the temperature and initial composition data of molten iron provides a basis for the control of converter composition.

2. The composition control method for improving the machining accuracy of 20CrMnTi steel gears according to claim 1, characterized in that: Step 2: Converter smelting; Raw materials are prepared according to a ratio of ≥800 kg / t of molten iron consumption. Rust and impurities on the surface of scrap steel are cleaned in advance, the proportion of scrap steel added is controlled, and interference from external elements is reduced. The smelting process adopts a top and bottom blowing process. During the blowing process, iron ore is added in 2 to 3 batches, with each batch containing 400 to 900 kg, to help adjust the carbon content and the cleanliness of the molten steel. Precise temperature control is performed at the end of the blowing process, with the final temperature controlled at 1600~1650℃ and the final carbon content controlled at 0.05~0.12wt%, to avoid compositional deviation caused by overblowing; The slag-blocking device is activated simultaneously during tapping, and the tapping time is controlled within 3 to 6 minutes to prevent slag from entering the ladle and affecting the purity of the composition.

3. The composition control method for improving the machining accuracy of 20CrMnTi steel gears according to claim 1, characterized in that: Step 3: LF refining; After the ladle is placed in place, lime and pre-melted slag are added to form slag. The temperature is raised by electricity for 3-7 minutes. After the slag melts, the basicity is adjusted to 3.0-5.8, and the FeO content in the slag is kept ≤1.0wt% to form a stable and purified slag system. Add the alloys in the following order: carbon → silicon → manganese → chromium → titanium → aluminum. Stir with argon gas for 3-5 minutes after each alloy is added, with the flow rate controlled at 40-80 L / min.

4. The composition control method for improving the machining accuracy of 20CrMnTi steel gears according to claim 1, characterized in that: Step 3: LF refining; Adjust the carbon content to 0.17~0.24wt% to ensure the matching of gear carburization and strength; Adjust the silicon content to 0.16~0.38wt% to optimize the deoxidation effect of steel; Adjust the manganese content to 0.78~1.12wt% to stabilize the hardenability of the steel; Adjust the chromium content to 0.98~1.32wt% to control the amount of deformation during heat treatment; Adjust the titanium content to 0.038~0.105wt% to fix free nitrogen in the steel and suppress mixed crystals; Adjust the acid-soluble aluminum content to 0.014~0.042wt% to refine the austenite grains; Pure calcium wire is fed in at a uniform rate at the end of refining, with a feeding speed of 140~210m / min and a feeding amount of 130~170m / furnace, resulting in brittle inclusions in the modified steel. After the wire is fed, gently blow argon gas for ≥16 minutes at a flow rate of 20~50 L / min to promote the full floating of inclusions.

5. The composition control method for improving the machining accuracy of 20CrMnTi steel gears according to claim 1, characterized in that: Step 4: Vacuum degassing; The ladle is moved into the vacuum treatment station and evacuated to a vacuum level of ≤1mbar. The vacuum is maintained for 12~18min to remove hydrogen and nitrogen gases from the steel. During vacuum treatment, maintain weak argon gas stirring at a flow rate of 20-40 L / min, so that the auxiliary gas and small inclusions float to the surface. After the air is broken, samples are taken for testing, and the total oxygen content is controlled to be ≤16ppm and the nitrogen content is ≤55ppm. Control the content of residual elements: arsenic ≤ 0.016 wt%, tin ≤ 0.011 wt%, lead ≤ 0.011 wt%, antimony ≤ 0.011 wt%, bismuth ≤ 0.011 wt%, to reduce the risk of carburizing and crystal mixing and processing deformation.

6. The composition control method for improving the machining accuracy of 20CrMnTi steel gears according to claim 1, characterized in that: Step 5: Continuous casting; The process involves full-process protective casting, with a 30-50mm thick layer of covering agent and carbonized rice husks spread on the tundish to prevent the molten steel from being exposed and oxidized. The superheat of the tundish is controlled at 20~40℃, and the liquid level is stable at ≥600mm to reduce the tendency of component segregation. The continuous casting speed is controlled at 0.75~0.95m / min, and combined with the crystallizer and end electromagnetic stirring, dendrite segregation is weakened; Samples of molten steel from the tundish were taken periodically to detect fluctuations in carbon, manganese, and chromium levels, with the cross-sectional composition range controlled to be ≤0.012wt%. Unstable billets are cut and removed separately during the initial casting and re-casting stages to ensure the consistency of the finished product composition.

7. The composition control method for improving the machining accuracy of 20CrMnTi steel gears according to claim 1, characterized in that: Step 6: Closed-loop detection of finished product components; Steel samples were taken from each heat for full element analysis, covering the main alloy, harmful elements, residual elements and gas content; Simultaneous detection of non-metallic inclusions, austenite grain size, and banded structure indicators: coarse inclusions (Class B) ≤ 1.5 grade, grain size ≥ 6 grade, and banded structure ≤ 2.5 grade; According to the internal control composition range, if the batch is unqualified, the process parameters should be adjusted and the batch should not proceed to the subsequent rolling process; Record the composition data throughout the entire process, and continuously optimize parameters based on processing accuracy feedback to form a closed loop for quality control.