Multi-specification rolling and performance guaranteeing process for alloy structural steel bars

Abstract

The invention relates to the technical field of steel bar rolling, and discloses an alloy structure steel bar multi-specification rolling and performance guarantee process which comprises the steps of S1 raw material preparation, S2 heating process, S3 rolling process, S4 finishing and collecting process, S5 inspection and acceptance flow and S6 delivery condition management. According to the technology, a clear rolling range is formulated for blanks of different specifications, for example, 150 square billets are used for rolling bars with the diameter being 20-50 mm, 180 square billets correspond to bars with the diameter being 20-70 mm, 240 square billets and 280 square billets are suitable for bars with the diameter being 20-100 mm, the accurate blank and specification matching mode is combined with advanced rolling equipment and technological parameter control, and the rolling efficiency is improved. By means of the technical scheme, enterprises can rapidly adjust the production specification according to market requirements, the production flexibility is greatly improved, meanwhile, in the rolling process, the size, the appearance and the allowable deviation are strictly controlled, the product specification accuracy is effectively guaranteed, and the diversified specification requirements of different industries for alloy structural steel bars are met.

Description

Technical Field

[0001] The present invention relates to the technical field of steel bar rolling, and specifically to a multi - specification rolling and performance guarantee process for alloy structural steel bars. Background Art

[0002] In the modern industrial system, alloy structural steel bars, as important basic materials, are widely used in many fields such as machinery manufacturing, automotive industry, aerospace, etc. With the continuous development and upgrading of various industries, more stringent requirements are put forward for the quality, performance, and specification diversity of alloy structural steel bars.

[0003] From the perspective of market demand, the specification requirements for alloy structural steel bars vary greatly in different application scenarios. In the field of machinery manufacturing, bars used to manufacture precision parts may require smaller diameter specifications to meet the requirements of high - precision machining; while in construction projects and large - scale machinery manufacturing, large - specification bars are often needed to bear huge loads. The traditional production process has obvious deficiencies in the flexibility of specification rolling and is difficult to quickly and efficiently switch to produce products of different specifications, which to a certain extent limits the enterprise's response speed and satisfaction ability to market demand.

[0004] In terms of product quality and performance, the performance of alloy structural steel bars is directly related to the quality and safety of downstream products. For example, in the manufacture of automobile engines, the alloy structural steel bars used need to have high strength, good toughness, and stable hardenability to ensure the reliable operation of the engine under complex working conditions. However, the early production process had many difficulties in controlling the chemical composition uniformity, internal tissue defects, and surface quality of steel. In terms of chemical composition control, it was difficult to accurately stabilize the content of various alloying elements within the target range, resulting in large fluctuations in the performance of steel; in terms of internal structure, defects such as porosity and segregation were likely to occur, affecting the mechanical properties of steel; surface quality also often had defects such as cracks and scabs due to process problems in rolling and finishing, reducing the product qualification rate and service life.

[0005] In addition, with the enhancement of environmental awareness and the deep - rooted concept of sustainable development, the steel industry is facing great pressure on energy conservation and emission reduction. Traditional heating and cooling processes often have problems of low energy utilization rate and large emissions, which not only increase production costs but also do not meet environmental protection requirements. Against this background, it is extremely urgent to develop an alloy structural steel bar production process that can achieve multi - specification rolling, guarantee high - performance products, and at the same time take into account energy conservation and environmental protection. Summary of the Invention

[0006] (I) Technical Problems to be Solved In view of the deficiencies of the prior art, the present invention provides a multi - specification rolling and performance guarantee process for alloy structural steel bars, which has the advantages of improving the flexibility and accuracy of specification rolling, and solves the problem that the traditional production process has obvious deficiencies in the flexibility of specification rolling, making it difficult to quickly and efficiently switch to produce products of different specifications, which to a certain extent restricts the response speed and satisfaction ability of enterprises to market demands.

[0007] (2) Technical solutions To achieve the above - mentioned purpose of improving the flexibility and accuracy of specification rolling, the present invention provides the following technical solutions: A multi - specification rolling and performance guarantee process for alloy structural steel bars, including S1 raw material preparation, S2 heating process, S3 rolling process, S4 finishing and collecting process, S5 inspection and acceptance process, and S6 delivery condition management. The S1 raw material preparation: Strictly control the billet size, weight, shape, and surface quality during raw material acceptance. Different - specification billets correspond to different rolling ranges: 150 - square billets are rolled into Φ20 - Φ50mm; 180 - square billets are rolled into Φ20 - Φ70mm; 240 - square billets and 280 - square billets are rolled into Φ20 - Φ100mm. It is necessary to accurately match the billets with the target specifications to lay the foundation for subsequent rolling. S2 heating process: The heating zone is a key link to ensure the performance of steel. The heating temperature and residence time in the furnace depend on the billet specifications. For 150×150mm billets, the pre - heating section temperature ≤700℃, time ≥50min, the heating section and soaking section temperature is 1220±20℃, the high - temperature section time ≥60min, and the total time ≥150min. When hot charging and hot delivery, the requirements for the pre - heating section are variable. Priority is given to ensuring the soaking section time, and the temperature is adjusted according to the actual situation to prevent steel from bending. If the accident time exceeds 20min, the heating temperature needs to be reduced; when the yin - yang surface of the continuous casting billet is obvious, rolling should be stopped to wait for the temperature to ensure uniform billet temperature. S3 rolling process; S4 finishing and collecting process; S5 inspection and acceptance process: Inspection items and methods: For different internal steel grades, determine the inspection items, sampling quantity, sampling location, and test methods for chemical composition, macrostructure, and banded structure. For chemical composition, sampling is carried out according to GB / T20066 and analyzed using GB / T223 and GB / T4336; for macrostructure, two specimens are taken from different steel bars and inspected according to GB / T226 and GB / T1979. Quality judgment criteria: Chemical composition is judged according to internal control composition, and the composition deviation of round billets complies with the provisions of GB / T222; there are strict judgment criteria for surface quality, macrostructure, and hardenability. Cracks are not allowed on the surface, there are corresponding grade limits for macrostructure grading, and there are specific requirements for hardenability according to different steel grades. S6 delivery condition management: Length requirements: The length of the steel is supplied according to the contract. The multiple-length or fixed-length shall be specified in the contract. The allowable deviation is (0, +50 mm). There is a short-length limit (4 m for 42CrMoH-8, and not less than 2.5 m for others). The delivery quantity of short-length shall not exceed 5% and shall be separately packaged. Handling of special requirements: When the user has special requirements, inspection and acceptance shall be carried out according to the contract or technical agreement to meet personalized needs. For the 42CrMoH-7 agreement steel, it is delivered in fixed-length or multiple-length of 5000 - 8000 mm, and there are regulations on length deviation and heat number. For the 20CrMoH-6 agreement steel, there are restrictions on the delivery quantity and length of non-fixed-length.

[0008] Among them, the S3 rolling process includes the S301 descaling operation, the S302 equipment inspection and maintenance, and the S303 cooling process. Among them, the S4 finishing and collecting process includes the S401 identification management, the S402 appearance quality treatment, and the S403 sawing and bundling.

[0009] Preferably, for the S301 descaling operation: During rolling, turn on the high-pressure water descaling with a pressure ≥ 26 MPa. Regularly check the header and nozzles of the descaling box, and promptly handle problems such as water leakage and blockage to ensure the surface quality of the steel and remove the scale.

[0010] Preferably, for the S302 equipment inspection and maintenance: The conditions of the head-removing stand, rolling grooves, baffles, guide guards, loopers, and roller tables affect the quality of the steel. The accuracy of the head-removing stand is controlled within ±5 mm of the standard position; if there are sharp corners and burrs on the equipment, they shall be polished or replaced in time; check the wear of the rolling grooves, cooling water pipes, and guide guards during shift handover and mid-shift shutdown, and handle problems immediately when found.

[0011] Preferably, for the S303 cooling process: The round steel adopts the cold bed insulation cover process to enter the pit for slow cooling (the entering pit temperature ≥ 300 °C), and the slow cooling time is not less than 24 hours. Control the cooling rate to improve the internal structure and performance of the steel.

[0012] Preferably, for the S401 identification management: Abide by the "system of delivering steel by heat" throughout the production process, do a good job in separating numbers and identification to prevent mixing of quality and numbers, and facilitate quality traceability and management.

[0013] Preferably, for the S402 appearance quality treatment: Strictly control the quality of the steel ends to ensure smoothness and no defects; operate carefully to avoid pulling and scratching; straighten when the camber exceeds the national standard of 4 mm / m; handle surface defects to meet the quality requirements.

[0014] Preferably, for the S403 sawing and bundling: Prevent the steel from bending during sawing, check the shear blades during shearing, and promptly handle problems such as wear and foreign matters; bundle the fixed-length and short-length separately, and bundle the non-standard fixed-length materials after treatment.

[0015] (III) Beneficial effects Compared with the prior art, the present invention provides a multi - specification rolling and performance guarantee process for alloy structural steel bars, which has the following beneficial effects: 1. For the multi - specification rolling and performance guarantee process of alloy structural steel bars, the flexibility and accuracy of specification rolling are improved: This process has defined clear rolling ranges for billets of different specifications. For example, 150 - square billets are used to roll bars with a diameter of Φ20 - Φ50mm, 180 - square billets correspond to Φ20 - Φ70mm, and 240 - square billets and 280 - square billets are applicable to Φ20 - Φ100mm. This precise matching method of billets and specifications, combined with advanced rolling equipment and process parameter control, enables enterprises to quickly adjust production specifications according to market demand, greatly improving the production flexibility. At the same time, during the rolling process, strict control is carried out on dimensions, shapes, and allowable deviations. For example, the allowable deviation of the nominal diameter of steel conforms to the relevant provisions of GB / T702, and the size of 42CrMoH - 7 is executed within - 0.5 ~ +1.3mm, effectively ensuring the accuracy of product specifications and meeting the diverse specification requirements of alloy structural steel bars in different industries.

[0016] 2. For the multi - specification rolling and performance guarantee process of alloy structural steel bars, the product quality and performance are significantly improved: Through a strict raw material acceptance system, the dimensions, weights, shapes, and surface qualities of continuous casting billets are controlled according to enterprise standard Q / OHAB107, ensuring product quality from the source. In the heating link, the heating temperature and residence time in the furnace are precisely controlled. For example, the preheating section, heating section, and soaking section temperatures and the time for each stage of 150×150mm billets are clearly specified to ensure uniform overall temperature of the cast billets and prevent the occurrence of yin - yang surfaces, providing good billet conditions for subsequent rolling. During the rolling process, high - pressure water descaling (pressure ≥ 26MPa) is turned on, and the descaling equipment is regularly inspected to effectively remove the oxide scale on the surface of the steel, improving the surface quality. At the same time, strict inspection and maintenance are carried out on equipment such as rolling grooves and guides to avoid surface scratches and internal tissue defects of the steel. In the cooling process, the cold bed insulation cover process is adopted for slow cooling in the pit (the temperature entering the pit ≥ 300℃, and the slow - cooling time is not less than 24 hours), optimizing the internal structure of the steel and enhancing the comprehensive performance. In the inspection link, comprehensive and strict inspection items and judgment criteria are set, covering multiple aspects such as chemical composition, macrostructure, and hardenability. For example, detailed end - quenching requirements for the hardenability of different steel grades are specified to ensure stable and reliable product quality. Specific embodiments

[0017] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0018] This solution provides a technical solution, specifically: a multi-specification rolling and performance guarantee process for alloy structural steel bars, including the following specific process steps. S1 Raw material preparation: Strictly control the billet size, weight, shape and surface quality during raw material acceptance. Different specifications of billets correspond to different rolling ranges: 150-square billets are rolled into Φ20-Φ50mm; 180-square billets are rolled into Φ20-Φ70mm; 240-square billets and 280-square billets are rolled into Φ20-Φ100mm. It is necessary to accurately match the billets with the target specifications to lay a foundation for subsequent rolling. S2 Heating process: The heating zone is a key link to ensure the performance of steel. The heating temperature and residence time in the furnace depend on the billet specifications. For 150×150mm billets, the temperature in the preheating section is ≤700°C and the time is ≥50min. The temperatures in the heating section and soaking section are 1220±20°C. The time in the high-temperature section is ≥60min and the total time is ≥150min. When hot charging and hot delivery, the requirements for the preheating section are variable. Priority should be given to ensuring the soaking time, and the temperature should be adjusted according to the actual situation to prevent steel from bending. If the accident time exceeds 20min, the heating temperature needs to be reduced; when the yin and yang sides of the continuous casting billet are obvious, rolling should be stopped and waiting for temperature to ensure uniform billet temperature. S3 Rolling process: S301 Descaling operation: Turn on high-pressure water descaling during rolling, with the pressure ≥26MPa. Regularly check the headers and nozzles of the descaling box, and promptly handle problems such as water leakage and blockage to ensure the surface quality of the steel and remove scale. S302 Equipment inspection and maintenance: The conditions of equipment such as the unheading stand, rolling grooves, baffles, guides, loopers, and roller tables affect the quality of steel. The accuracy of the unheading stand is controlled within ±5mm of the standard position; if there are sharp corners and burrs on the equipment, they should be polished or replaced in time; check the wear of the rolling grooves, cooling water pipes and guides during shift change and mid-shift shutdown, and handle problems immediately when found. S303 Cooling process: The round steel adopts the cold bed insulation cover process to enter the pit for slow cooling (the temperature entering the pit ≥300°C), and the slow cooling time is not less than 24 hours to control the cooling rate and improve the internal structure and performance of the steel. S4 Finishing and collecting process: S401 Identification management: Abide by the "System of Delivering Steel by Heat" throughout the production process, do a good job in separating numbers and identification to prevent mixing of quality and numbers, and facilitate quality traceability and management. S402 Appearance quality treatment: Strictly control the quality of the steel ends to ensure they are flat and defect-free; operate carefully to avoid bending and scratching; straighten when the camber exceeds the national standard of 4 mm / m; handle surface defects to meet the quality requirements. S403 Sawing and bundling: Prevent bends during sawing, check the shear blades during shearing, and promptly handle problems such as wear and foreign objects; bundle the specified-length and short-length materials separately, and bundle the non-standard specified-length materials after treatment. S5 Inspection and acceptance process: Inspection items and methods: For different internal steel grades, determine the inspection items such as chemical composition, macrostructure, and banded structure, as well as the sampling quantity, location, and test methods. For chemical composition, sample according to GB / T20066 and analyze using GB / T223 and GB / T4336; for macrostructure, take two specimens from different steel bars and inspect according to GB / T226 and GB / T1979. Quality judgment criteria: Judge the chemical composition according to the internal control composition, and the composition deviation of round billets shall comply with the provisions of GB / T222; there are strict judgment criteria for various properties such as surface quality, macrostructure, and hardenability. Cracks and other defects are not allowed on the surface, there are corresponding grade limits for the macrostructure rating, and there are specific requirements for hardenability according to different steel grades. S6 Delivery condition management: Length requirements: The length of the steel is supplied according to the contract. The multiple-length or specified-length shall be noted in the contract, with an allowable deviation of (0, +50 mm), and there is a short-length limit (4 m for 42CrMoH-8, not less than 2.5 m for others). The short-length delivery quantity shall not exceed 5% and shall be packaged separately. Handling of special requirements: When the user has special requirements, conduct inspections and acceptance according to the contract or technical agreement to meet personalized needs. For 42CrMoH-7 agreement steel, it is delivered in specified-length or multiple-length of 5000 - 8000 mm, with regulations on length deviation, heat number, etc.; for 20CrMoH-6 agreement steel, there are restrictions on the non-specified-length delivery quantity and length.

[0019] Furthermore, the rolling flexibility and precision of this process are improved: This process has defined clear rolling ranges for billets of different specifications. For example, 150-square billets are used for rolling bars with a diameter of Φ20 - Φ50mm, 180-square billets correspond to Φ20 - Φ70mm, and 240-square billets and 280-square billets are applicable to Φ20 - Φ100mm. This precise matching method of billets and specifications, combined with advanced rolling equipment and process parameter control, enables the enterprise to quickly adjust the production specifications according to market demand, greatly improving the production flexibility. At the same time, during the rolling process, strict control is exerted over dimensions, shapes, and allowable deviations. For example, the allowable deviation of the nominal diameter of the steel conforms to the relevant provisions of GB / T702, and the dimensions of 42CrMoH - 7 execute - 0.5 ~ +1.3mm, effectively ensuring the precision of the product specifications and meeting the diverse specification requirements of alloy structural steel bars in different industries; Furthermore, the quality and performance of the products of this process are significantly improved: Through a strict raw material inspection system, the dimensions, weights, shapes, and surface qualities of continuous casting billets are controlled according to the enterprise standard Q / OHAB107, ensuring product quality from the source. In the heating process, the heating temperature and residence time in the furnace are precisely controlled. For example, the temperatures and times of the preheating section, heating section, and soaking section of 150×150mm billets are clearly specified to ensure uniform overall temperature of the billets and prevent the occurrence of uneven heating on both sides, providing good billet conditions for subsequent rolling. During the rolling process, high-pressure water descaling (pressure ≥26MPa) is started, and the descaling equipment is regularly inspected to effectively remove the scale on the surface of the steel and improve the surface quality; at the same time, strict inspection and maintenance are carried out on equipment such as rolling grooves and guides to avoid surface scratches and internal structure defects of the steel. In the cooling process, the cold bed insulation cover process is adopted for slow cooling in the pit (the temperature entering the pit ≥300℃, and the slow cooling time is not less than 24 hours), optimizing the internal structure of the steel and enhancing the comprehensive performance. In the inspection process, comprehensive and strict inspection items and judgment criteria are set, covering multiple aspects such as chemical composition, macrostructure, and hardenability. For example, detailed end-quench requirements for the hardenability of different steel grades are specified to ensure stable and reliable product quality.

[0020] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Multi-specification rolling and performance assurance process for alloy structural steel bars, including S1 raw material preparation, S2 heating process, S3 rolling process, S4 finishing and collection process, S5 inspection and acceptance process and S6 delivery condition management, characterized by: The S1 raw material preparation: The raw material acceptance strictly controls the size, weight, shape and surface quality of the billet. Different specifications of billets correspond to different rolling ranges: 150 square billets are rolled into Φ20-Φ50mm; 180 square billets are rolled into Φ20-Φ70mm; 240 square billets and 280 square billets are rolled into Φ20-Φ100mm. The billets must be accurately matched with the target specifications to lay the foundation for subsequent rolling. S2 heating process: The heating zone is the key link to ensure the performance of steel. The heating temperature and time in the furnace depend on the specifications of the billet. For 150×150mm billet, the preheating temperature is ≤700℃ and the time is ≥50min. The temperature of the heating and soaking sections is 1220±20℃, the high temperature section time is ≥60min, and the total time is ≥150min. The preheating section requirement is variable during hot charging and hot delivery, and the soaking section time is given priority. At the same time, the temperature is adjusted according to the actual situation to prevent bending of steel. If the accident time exceeds 20min, the heating temperature needs to be reduced. When the positive and negative sides of the billet are obvious, the rolling should be stopped to wait for the temperature to ensure that the billet temperature is uniform. S3 rolling process; S4 finishing collection process; S5 inspection and acceptance process: Inspection items and methods: for different internal steel grades, determine the inspection items of chemical composition, macrostructure, and banded structure as well as the sampling quantity, location and test method. The chemical composition is sampled according to GB / T20066 and analyzed using GB / T223 and GB / T4336; for macrostructure, take two samples from different steels and inspect them according to GB / T226 and GB / T1979; Quality judgment standard: Chemical composition is determined according to the internal control composition, and the round billet composition deviation complies with the provisions of GB / T222; Surface quality, macrostructure, and hardenability are all subject to strict judgment standards. Crack defects are not allowed on the surface, macrostructure rating has corresponding level restrictions, and hardenability has specific requirements for different steel grades; S6 Delivery Condition Management: Length requirements: Steel length is supplied according to the contract. Multiple length or fixed length shall be specified in the contract. The allowable deviation is (0, +50mm). There is a short length limit (42CrMoH-8 is 4m, others are not less than 2.5m). The short length delivery quantity shall not exceed 5% and shall be packed separately. Special requirements processing: When users have special requirements, inspection and acceptance will be carried out according to the contract or technical agreement to meet personalized needs. 42CrMoH-7 agreement steel is delivered in fixed length or multiple lengths of 5000-8000mm, and there are regulations on length deviation and furnace number; 20CrMoH-6 agreement steel has restrictions on non-fixed length delivery quantity and length; Among them, the S3 rolling process includes S301 descaling operation, S302 equipment inspection and maintenance, and S303 cooling process; Among them, the S4 finishing and collection process includes S401 identification management, S402 appearance quality processing and S403 sawing and bundling.

2. The multi-specification rolling and performance assurance process for alloy structural steel bars according to claim 1, characterized in that: The S301 descaling operation: turn on high-pressure water descaling during rolling, with a pressure ≥ 26MPa, regularly check the descaling box header and nozzle, and deal with leakage and blockage problems in a timely manner to ensure the surface quality of the steel and remove iron oxide.

3. The multi-specification rolling and performance assurance process for alloy structural steel bars according to claim 1, characterized in that: Inspection and maintenance of the S302 equipment: The conditions of the stripping stand, rolling groove, baffle, guide, looper and roller table affect the quality of steel. The accuracy of the stripping stand is controlled within ±5mm of the standard position. Sharp corners and burrs on the equipment should be polished or replaced in time. Check the wear of the rolling groove, cooling water pipes and guides during shift changes and mid-shift shutdowns, and deal with any problems immediately.

4. The multi-specification rolling and performance assurance process for alloy structural steel bars according to claim 1, characterized in that: The S303 cooling process: round steel adopts the cooling bed insulation cover process to enter the pit for slow cooling (entry temperature ≥ 300°C), the slow cooling time is not less than 24 hours, the cooling speed is controlled, and the internal structure and performance of the steel are improved.

5. The multi-specification rolling and performance assurance process for alloy structural steel bars according to claim 1, characterized in that: The S401 identification management: The "Steel Delivery System by Furnace" must be followed throughout the production process, and separation and identification must be done properly to prevent mixing of quality and numbers, and facilitate quality traceability and management.

6. The multi-specification rolling and performance assurance process for alloy structural steel bars according to claim 1, characterized in that: The S402 appearance quality treatment: strictly control the quality of the steel ends to ensure flatness and no defects; carefully operate to avoid bending and scratching; Straighten when the curvature exceeds the national standard by 4mm / m; Treat surface defects and meet quality requirements.

7. The multi-specification rolling and performance assurance process for alloy structural steel bars according to claim 1, characterized in that: The S403 sawing and bundling: prevent bending when sawing, check the shear blade when shearing, and deal with wear and foreign matter problems in time; the fixed length and short length are bundled separately, and the fixed length materials that do not meet the standards are processed before bundling.