最新刊期
- 摘要：To improve the efficiency and reduce the energy consumption of an electromagnetic induction heater for steel ingot riser， an optimization method for the yoke is proposed. Using ANSYS multi-physics coupling simulation， the effects of the yoke on the magnetic field distribution， heating efficiency， and solidification of the steel ingot riser were analyzed. The results show that when the yoke is expanded to 130% of the coil area and its thickness is increased to 120 mm， magnetic flux leakage at the edges is suppressed under the same working conditions. This increases the magnetic flux density on the molten steel surface by approximately 80% and increases the Joule heating power by about 2.5 times. Meanwhile， the temperature distribution in the riser region becomes more uniform， solidification of the ingot is delayed， and the feeding channel duration at the riser line is extended by 18 min. Under the same excitation current of 692 A， this optimized design increases the heating power from 10.67 kW before optimization to 26.58 kW， achieving an efficient heating mode of "low current， high power" while reducing coil losses.关键词：Yoke;Induction Heating;Steel Ingot Riser;Heating Efficiency;Numerical Simulation2|0|0更新时间：2026-04-08
- 摘要：GCr15 is a typical representative of high-carbon chromium bearing steel， and surface decarburization can severely degrade its surface quality and service performance. This paper presents an experimental investigation and mechanism analysis on the isothermal decarburization behavior of GCr15 bearing steel in air， N₂+H₂+H₂O and N₂+H₂O atmospheres. The results show that in air atmosphere， no decarburization layer was observed at 700 ℃， a fully decarburized layer and a partially decarburized layer were observed at 800 ℃， and only a partially decarburized layer was present above 900 ℃. Compared with hypoeutectoid steel， GCr15 exhibits a decarburization layer covering a wide range of carbon content. Coupled with the strong sensitivity of room-temperature microstructure to the cooling rate after isothermal decarburization， the evolution of room-temperature microstructure in the decarburization layer with decarburization time is complex. The hardness method， rather than the metallographic method， is the preferred method for measuring decarburization depth. The total decarburization layer thickness increases with rising temperature and holding time， reaching 511， 690， 960， and 1 270 μm after isothermal treatment at 700， 800， 900， and 1 000 ℃ for 120 min respectively. In comparison with the N₂+H₂+H₂O atmosphere， the strong oxidizability of the N₂+H₂O atmosphere results in the oxidative ablation of the decarburized ferrite layer and even a certain proportion of the partially decarburized layer. The results of this study provide guidance for decarburization layer control during the thermal processing design of GCr15 steel.关键词：GCr15 Bearing Steel;Surface Decarburization;Heating Atmosphere;Hardness Method2|0|0更新时间：2026-04-08
- 摘要：To enhance the efficiency of the RH vacuum refining system a physical model of a 150 t RH vacuum refining system incorporating a vacuum chamber， snorkels， and ladle was established. The Euler-Euler two-fluid method was adopted for numerical simulations to systematically investigate the effects of different downcomer-to-riser diameter ratios on the circulation characteristics and refining performance of the RH device. The flow velocity at each position， flow field of the main cross-section， agitation effect on the molten steel at the ladle bottom， circulation flow rate， and mixing time under different diameter ratios（1-1.4） were analyzed for various diameter ratios. The results show that increasing the downcomer diameter significantly enhances the circulation flow rate（390 kg/s-492 kg/s）， while the mixing time decreases （286 s–269 s）. The flow field in the ladle tends to concentrate in the region between the two snorkels， the flow field in the vacuum chamber improves， and the proportion of the active region of molten steel at the ladle bottom decreases （from 39% to 19%）. Considering all factors， the optimal diameter ratio of the downcomer to the riser is 1.2， which can balance the improvement of the circulation flow rate and maintain excellent molten steel stirring capability.关键词：RH Vacuum Refining;Snorkels Structure;Molten Steel Flow Field;Stirring Performance2|0|0更新时间：2026-04-08
- 摘要：Laser polishing can effectively improve the surface quality of cold work die steel Cr12MoV. To explore the influencing factors of surface quality during laser polishing， an orthogonal experimental design was employed to formulate the experimental protocol. Cr12MoV die steel surfaces were treated using varying laser polishing parameters. Through characterization of the polished layer microstructure and geometric features such as cracks， the mechanisms underlying crack initiation and propagation during laser polishing of Cr12MoV die steel were examined. SPSS software was utilized to assess the influence patterns of laser polishing parameters on surface quality metrics of the polished regions， including remelted zone depth， polished layer depth， surface roughness， and crack formation. The results show that the surface roughness of all polished die steel specimens across experimental groups was reduced compared to the original surface， with the minimum value reaching 0.944 μm， decreased by 88.8% relative to the original surface. Crack formation was observed on the polished surfaces of die steel specimens in certain groups subjected to higher polishing power. During laser polishing of Cr12MoV die steel， laser process parameters directly effect surface quality indicators such as remelted zone depth， polished layer depth， crack dimensions， and surface roughness. Among these parameters， laser power and scanning speed are significant factors affecting the aforementioned surface quality metrics， whereas the influence of overlap rate is non-significant. Optimal selection of laser polishing process parameters can effectively enhance the surface quality of Cr12MoV die steel.关键词：Cr12MoV;Laser polishing;Process Parameter;Cracking;Thermal effect2|0|0更新时间：2026-04-08
- 摘要：In this paper， the microstructure， hardness， strength and plasticity of the Al-containing corrosion-resistant steel at different cooling rates and temperatures were studied. The corrosion resistant steel was rolled by reversible rolling mill and continuous cooling transformation （CCT） test and the high temperature tensile test were carried out. The results show that Al has a significant effect on the microstructure evolution of the corrosion resistant steel. With the increase of Al content， the ferrite phase region expands， the occurrence temperature of bainite phase region decreases， and the effect of cooling rate on the microstructure morphology is more obvious. The hardness test shows that the hardness increases significantly with the increase of cooling rate， especially when bainite transformation occurs and bainite structure is formed. When the w［Al］ content is 0.5%， the hardness of the Al-containing corrosion-resistant steel is higher than that when the w［Al］ content is 1.0 %. Moreover， the maximum force value at 1 300 ℃ for the steel with 0.5% w［Al］ is 21.9 kgf， indicating better high-temperature strength and ductility. The strength-plasitcity test reveals the difference in mechanical behavior of the two steels at different temperatures， especially the control of the brittle temperature range is important for industrial production. The fracture mechanism of the material at different temperatures is further clarified by microscopic fracture analysis. This study provides a theoretical basis and technical support for the application of the Al-containing corrosion-resistant steel.关键词：Al Content;High Temperature Properties;Phase Transformation Behavior;Microstructure2|0|0更新时间：2026-04-08
- 摘要：In order to optimize the tundish induction heating system， the influence of channel abduction angle on the distribution of electromagnetic field was studied. A three-dimensional electromagnetic field mathematical model was established to simulate the distribution characteristics of magnetic induction intensity， induced current density and Joule heat when the channel abduction angle changes in the range of 2° to 10°， taking a two-strand tundish with large nozzle spacing （5 550 mm） in a steel plant as the object. The calculation results show that under the same heating power， as the abduction angle increases， the geometric position of the channel shifts relative to the coil， resulting in a downward trend in magnetic induction intensity， current density and Joule heat， and this attenuation is most significant in the channel outlet area， indicating that the magnetic field energy loss is mainly concentrated in the second half of the channel. The magnetic field shows a stable eccentric distribution on the central section of the channel， and the electromagnetic parameters near the coil side are higher. Through comprehensive analysis， it is determined that the 2° abduction angle is the best design parameter. At this angle， the magnetic induction intensity at the near coil side can reach 0.188 T， and the overall induced current density is higher than 1.70×10⁶ A/m². Therefore， in practical engineering design， it is recommended to use 2° or adjacent small outreach angles to maximize electromagnetic coupling efficiency and improve heating performance.关键词：Tundish;Induction Heating;Angle of Channel;Electromagnetic Field;Numerical Simulation2|0|0更新时间：2026-04-08
- 摘要：Cold-rolled ultrahigh-strength dual-phase steel（chemical composition/%：0.220C，0.470Si， 2.500Mn，0.410Cr，0.050Al，0.020Nb） was intercritical annealed by a laboratory continuous annealing simulation machine to investigate the effect of annealing processes on microstructure and mechanical properties. The results show that a microstructure containing ferrite and martensite can be obtained. The martensite phase contributes to the high strength of dual-phase steel. Carbide precipitation during intercritical annealing contributes to precipitation strengthening. The presence of the retained austenite contributes to the combination of high strength and ductility of dual-phase steel. During intercritical annealing， prolonging the holding time leads the steel into an equilibrium stage of austenite growth. Consequently， the tensile strength gradually increases while the elongation decreases， both tending to stabilize after holding for more than 180 s. Excellent comprehensive mechanical properties that the tensile strength 1 350 MPa， yield strength 745 MPa， yield strength ratio 0.55， elongation 8%， and the strength-plasticity-product 10 800 MPa·% can be obtained when the cold-rolled ultrahigh-strength dual-phase steel holds 180 s at 820 ℃.关键词：Ultra-high-strength Dual-phase Steel;Intercritical Annealing;Holding Time;Martensite Islands2|0|0更新时间：2026-04-08
- 摘要：This study investigates the vacuum arc remelting （VAR） process of a
- 摘要：Using metallographic examination， cold heading， and other experimental methods， this study investigates the optimization of the pinch roll groove system and clamping pressure in high-speed wire rod rolling processes to address the issue of coarse surface microstructure in piston rod steel S45C，which affects material fatigue strength and wear resistance. Analysis indicates that improper design of the pinch roll groove and inappropriate light/heavy pressure parameter settings lead to localized stress concentration on the steel surface， inducing coarse microstructure. Reducing the light and heavy pressure of the laying head pinch roll by 0.2 MPa significantly decreases surface stress and mitigates the degree of coarse surface structure. Optimizing the pinch roll groove by changing the contact between the laying head pinch roll and the red steel from point contact to surface contact alleviates clamping stress. Combined with reduced pinch roll pressure， this approach effectively resolves the coarse surface microstructure issue in piston rod steel S45C. In summary， the optimal production process involves using groove B with a heavy pressure of 0.35 MPa and a light pressure of 0.15 MPa. The resulting microstructure is uniform ferrite and pearlite， with no coarse structure at the edges. Customer validation confirms that the optimized S45C piston rod steel exhibits significantly improved surface microstructure uniformity， meeting high-precision application requirements and providing a reliable pathway for process improvements in similar products.关键词：High Speed Wire Clamp Roller;Coarse Microstructure;Hole Type;Light and Heavy Pressure;S45C Steel2|0|0更新时间：2026-04-07
- 摘要：The high temperature mechanical properties of medium manganese wear-resistant steel with different rare earth content had been systematically studied by using Gleeble 3500 thermal simulation testing machine， SEM （scanning electron microscope）， OLS4100 confocal microscope and metallographic microscope. The results showed that the maximum high temperature tensile strengthen of medium manganese steel increased from 396.64， 228.07， 113.25， 75.15， 42.97， 25.11 MPa to 414.85， 238.28， 130.59，76.14， 44.59，28.09 MPa respectively at 700， 800， 900，1 000， 1 100，1 200 ℃ with 0.038% rare earth content （mass fraction）. This is because the addition of rare earths can refine the grain size and increase the tensile strength. Metallographic experiments showed that the grain size of medium manganese steel increased from 6.80 grade to 7.12 grade when rare earth content was 0.038% compared with that without adding rare earth. It was found that the temperature of dynamic recrystallization of manganese in medium manganese steel was delayed from 800 ℃ to 900 ℃ by rare earth addition. In addition， the addition of rare earth can significantly increase the reduction area （R.A.） of medium manganese steel at 1 000 ℃-1 200 ℃ increased from 47.3%， 53.9%， 46.78% to 65.64%， 76.56%， 50.26% respectively. That is， the addition of rare earth significantly improves the high temperature thermoplasticity of medium manganese steel at 1 000 ℃-1 200 ℃.关键词：Medium Manganese Wear-resistant Steel;Rare Earth;High Temperature Thermoplastic;Reduction of Area;Dynamic Recrystallization2|0|0更新时间：2026-04-07
- 摘要：The problem of end face cracks in high-quality carbon steel continuous casting round billets with a diameter of 1 200 mm was investigated， with a production process.of 80 t BOF-LF-VD - ultra large size continuous casting machine - slow cooling of castings Measures such as multi-stage electromagnetic stirring， online insulation of castings， and slow cooling process were adopted. The continuous casting process parameters are as follows： casting speed of 0.06-0.11 m/min， tundish superheat of 15-35 ℃， continuous casting round billet charging temperature ≥ 500 ℃， and discharging temperature ≤ 350 ℃. Perform multidimensional correlation analysis using methods such as low magnification testing， scanning electron microscopy， and in situ analysis.Using TWS software and liquid core control model， the pulling speed parameters were optimized from 0.10 m/min to 0.07 m/min while keeping the electromagnetic stirring and superheat parameters unchanged.thereby improving the core quality of the casting billet and reducing low-magnification inspection center cracks from 1.0–2.0 levels to 0–0.5 levels. By using an online insulation cover， the end temperature of the continuous casting round billet increased by 102.4 ℃， and the slow-cooling pit capacity rose from 50% to over 80%. The cooling rate in the first two days decreased by more than 1 ℃/h. Inspection results showed that the crack length on the end face of the continuous casting round billet was reduced from 60–200 mm to 0–10 mm. Customers reported satisfactory results， and the improvements were effectively verified by the market， providing valuable reference for the industry.关键词：Oversized Specifications;Continuous Casting Round Billet;End-face Cracks;Continuous Casting Process2|0|0更新时间：2026-04-07
- 摘要：Focusing on the novel vertical electric arc furnace （EAF） process coupled with hot metal charging， this study conducted a systematic analysis and optimization of the process to address practical production issues such as high electricity consumption per ton of steel， endpoint over-oxidation， and prolonged smelting cycles. Through in-depth analysis of key process parameters including charging rhythm， oxygen supply regime， and energy input， a phased optimization strategy was proposed. This strategy systematically divides the process into three components： adjustment of scrap steel and hot metal ratio， optimization of oxygen lance operation， and enhancement of scrap preheating.Industrial trials demonstrated that after implementing the phased optimization， the electricity consumption per ton of steel was reduced to 188.70 kWh，a decrease of 15.30 kWh， the smelting cycle was shortened to 38.45 min （a reduction of 3.84 min）， and the endpoint oxygen content reached 5.19×10⁻⁶， indicating significant mitigation of over-oxidation. Both energy efficiency and production rhythm were substantially improved. This study validates the effectiveness of the phased control strategy and provides a systematic technical solution along with practical evidence for achieving efficient and stable operation of vertical EAFs under high hot metal ratio conditions.关键词：Shaft Electric Arc Furnace;High Hot Metal Ratio;Oxygen Supply Optimization;Charging Rhythm;Scrap Preheating2|0|0更新时间：2026-04-07
- 摘要：Improving steel cleanliness is a core strategy for steel enterprises to enhance product competitiveness and expand into high-end markets. Nitrogen is often regarded as a harmful element in steel， as excessively high levels can significantly deteriorate the plasticity， toughness， and durability of steel. Therefore， achieving low nitrogen control in molten steel is a key method for enhancing cleanliness. This review systematically outlines the thermodynamic and kinetic principles of nitrogen control during the steelmaking process and provides an in-depth analysis of key process factors affecting nitrogen content in steel， including： 1） The "blocking effect" of surface-active elements （O， S） on gas-liquid interface reactions and their critical content thresholds （e.g.， denitrification nearly stagnates when w［O］ > 0.04% or w［S］ > 0.06%）； 2） The denitrification effect of carbon-oxygen （CO） bubbles and how to prolong their effective denitrification duration through process optimization （e.g.， adding foaming agents）； 3） The chemical nitrogen absorption mechanism of slags with high nitrogen capacity and the regulation of nitrogen solubility by slag system components （e.g.， CaO/Al₂O₃ ratio， CaF₂ content）； 4） The thermodynamic advantages of low nitrogen partial pressure during vacuum treatment and the kinetic synergy with argon stirring； 5） The unique nitrogen pickup issue caused by arc ionization in electric arc furnaces and corresponding mitigation strategies. Based on this， the article summarizes industrial practices in low nitrogen control technology represented by ShanSteel， Shougang， and TISCO. Furthermore， this review critically examines nitrogen content prediction models that have emerged in recent years （such as Nam's dynamic converter model and Wei's time-dependent thermodynamic model for AOD）， highlighting through comparative analysis the existing limitations of these models in terms of universality， real-time capability， and adaptability to extreme operating conditions. Finally， the outlook points out that future low nitrogen steel production should focus on arc process optimization and global intelligent control， with particular emphasis on the promising new green metallurgical pathway of synergistic carbon and nitrogen removal through the formation of carbonitrides under the "dual-carbon" strategic background.关键词：Nitrogen Removal;Thermodynamics and Kinetics;Surface-active Elements;Nitrogen-absorbing Slag;Nitrogen Control Models2|0|0更新时间：2026-04-07
- 摘要：In this study， H13 hot work die steel， which is widely used in the blade of scrap steel shearing machine， is used as the benchmark material， and the alloy design strategy of “reducing Si， V and increasing W” is put forward. The influence of alloying element content on carbide precipitation behavior in H13 die steel was investigated， and the influence of heat treatment process on the microstructure and mechanical properties of experimental steel was systematically studied. The results show that after the contents of w［Si］， w［V］ and w［W］ are controlled in the ranges of 0.1%-0.3%， 0.5%-0.6% and 1.8%-2.2%， respectively， under the optimal heat treatment process， the hardness of the new steel is basically the same as that of H13 steel， but the impact toughness is twice that of H13 steel， and it shows excellent thermal stability and friction-wear properties. This study successfully developed a DPG20 hot work die steel specifically for the blade of scrap steel shearing machine， which exhibited excellent mechanical properties.关键词：Hot Work Die Steel;Composition Design;Thermodynamic Calculations;Impact Toughness;Wear2|0|0更新时间：2026-04-07
- 摘要：Hot-work die steel（DHA） steel was selected as the research object and adds Niobium （Nb） elements with mass fractions of 0， 0.009%， 0.019%， 0.028%， and 0.038% to the steel. The influence of Nb on the microstructure and mechanical properties of DHA steel was investigated. The results show that Nb addition promotes the formation of large-sized primary carbonitrides during solidification， and aggravates the secondary dendrites segregation in the as-cast microstructure. Nb addition refines the grain size of the experimental steel after tempering. With the increase of Nb mass fraction， toughness gradually decreases after tempering at 560 ℃ and 590 ℃， and first increases and then decreases after tempering at 620 ℃. Strength first increases and then decreases with increasing Nb content. Considering the comprehensive mechanical properties， when the mass fraction of Nb element is 0.019%， DHA steel has the best performance.关键词：Hot-work Die Steel;Niobium Content;Microstructure;Mechanical Properties2|0|0更新时间：2026-04-07
- 摘要：Based on currently commercial non-quenched and tempered steels， this study innovatively proposes a compositional design strategy of “reduced C， increased Si， and added Mn.” Through compositional regulation and microstructural optimization， a novel high-strength， high-toughness， and low-cost non-quenched and tempered steel with a tensile strength of approximately 1 300 MPa was successfully developed. The results indicate that the novel non-quenched and tempered steel （QGF17） has the following chemical composition （w/%）： 0.19C， 1.92Si， 2.90Mn， 0.56Cr， 0.012P， and 0.004S. The addition of Si optimizes the bainitic microstructure， leading to an increased volume fraction of lath bainite （LB）. Meanwhile， the grain size is refined from 18 μm to 11 μm， the fraction of high-angle grain boundaries （HAGBs） increases markedly from 28.5% to 59.1%， and the dislocation density also rises. As a result， localized high-dislocation-density regions form near grain boundaries and lath interfaces. Compared with FAS2225 steel， the novel non-quenched and tempered steel exhibits substantially improved， especially the hardness and mechanical properties. The HV hardness increases from 318 to 473， the yield strength and tensile strength rise from 710 MPa and 955 MPa to 973 MPa and 1 322 MPa， respectively， and the impact energy at -20 °C increases significantly from 16 J to 29 J. In addition， the novel steel demonstrates a higher strain-hardening capability and excellent impact toughness. The SEM fracture analysis reveals that although both steels exhibit quasi-cleavage fracture characteristics under impact loading， a pronounced plastic deformation zone is observed near the V-notch region in the novel non-quenched and tempered steel. Correspondingly， the fracture morphology evolves from river-pattern quasi-cleavage facets in FAS2225 steel to finer quasi-cleavage micro-facets in the novel steel. These results confirm that， through simplified alloying and optimized compositional design， the developed non-quenched and tempered steel effectively reduces production costs while overcoming the long-standing trade-off between strength enhancement and toughness degradation in conventional high-strength non-quenched steels， thereby providing a promising technological pathway for the engineering application of high-performance non-quenched and tempered steels.关键词：Non-quenched and Tempered Steel;Silicon;Low-temperature Impact Toughness;High-Angle Grain Boundary（HAGB）;Quasi-cleavage Fracture2|0|0更新时间：2026-04-07
- 摘要：To meet the stringent property demands of aviation fasteners， the development of aviation-grade 303Se free-cutting austenitic stainless steel cold-drawn bars was undertaken. Based on SAE AMS5640， the chemical composition was designed and refined by precisely controlling key elements to/%：≤0.03C ，0.03-0.06N ，0.30Se， 0.13P， to secure an optimum balance between machinability and mechanical strength. According to hot-ductility test results， the reheating soak temperature 1 220 ℃-1 260 ℃， the start rolling temperature 1 120 ℃-1 200 ℃， the finish rolling temperature ≥ 1 000 ℃ was established to roll the wire. the wire was cooled with water to room temperature after wire rod laying，and then cold drew with deformation of 15%-25%， to the
- 摘要：Under the national "Dual Carbon" goals， an environmentally friendly， coating-free， high-strength， and high-corrosion-resistant highway guardrail steel， LG500EW， has been developed. This addresses issues with traditional galvanized plain carbon steel Q235， such as low strength， poor corrosion resistance， and significant environmental pollution caused by galvanizing processes， thereby improving the safety and service life of highway guardrails while reducing carbon emissions across the entire industry chain. LG500EW employs a alloy design of low carbon， high chromium， and trace amounts of copper and nickel， combined with Thermo-Mechanical Control Process （TMCP） rolling to ensure corrosion resistance and formability. The actual tensile strength of the product can reach the 600 MPa .Using a temperature and humidity chamber for cyclic wet-dry tests， along with methods such as SEM analysis， metallographic analysis， corrosion weight loss measurement， and electrochemical analysis， the corrosion resistance of coating-free high-strength and high-corrosion-resistant steel LG500EW， galvanized plain carbon steel Q235， and conventional low-alloy steel Q355B was investigated in a simulated industrial marine atmospheric environment. The results show that in such an environment， both LG500EW and galvanized Q235 exhibit better atmospheric corrosion resistance than conventional low-alloy Q355B. As the simulated accelerated test duration increases， the corrosion rate of galvanized Q235 continues to rise until corrosion occurs beneath the coating on the iron substrate. In contrast， with prolonged exposure， a protective rust layer gradually forms on LG500EW steel. The outermost rust layer develops a relatively dense and complete plate-like corrosion product layer， with a significant increase in the diffraction peak intensity of α-FeOOH in the corrosion products. The self-corrosion potential rises while the self-corrosion current decreases. After 32 days of corrosion， the corrosion thinning of LG500EW steel is 90 μm， approximately twice that of galvanized Q235 （40 μm）， demonstrating excellent corrosion resistance.The environmentally friendly， coating-free， high-strength， and high-corrosion-resistant highway guardrail steel exhibits superior performance in industrial marine atmospheric environments compared to traditional guardrail steels. The developed steel has been successfully applied in coating-free highway guardrails， yielding significant economic， social， and ecological benefits.关键词：Coating-free;High-strength;High-corrosion-resistance;Highway Guardrail;Industrial Marine Atmospheric Environment;Alloy Design14|11|0更新时间：2026-01-10
- 摘要：The effects of different tempering temperatures and holding times on the microstructure and hardness of thick wall sulfur-resistant casing steel， which exhibits martensite （M） structure at the outer wall and martensite + bainite （M+B） structure at the middle wall after quenching， were investigated. The results show that in the tempering temperature range of 695 ℃-720 ℃， Rockwell hardness fluctuation caused by microstructure differences is 0.8 - 1 HRC. Both types of microstructure show a decreasing trend in Rockwell hardness with the prolongation of tempering holding time. But when the tempering holding time is 75 min - 85 min， both groups have obvious secondary hardening phenomenon. Microstructure observation on samples subjected to different tempering process shows that， solid solution carbon content of martensite structure is high， and the precipitation of carbon atoms during tempering leads to relatively fast hardness attenuation and poor tempering stability. However， the higher solid solution carbon content increases the percentage of vanadium carbide （VC） microalloyed precipitates， and the secondary hardening phenomenon compensates for the hardness degradation caused by carbon dissolution. In actual production， the uniform microstructure should be obtained as far as possible to reduce the hardness vaiation in the wall thickness range of the pipe. At the same time， tempering treatment should avoid the secondary hardening interval， so that the hardness value can meet the requirements of mechanical properties of sulfur-resistant pipes.关键词：Microstructure;Tempering Treatment;Thick Wall;Micro Alloy;Hardness Fluctuation9|21|0更新时间：2026-01-10
- 摘要：Carbon macrosegregation in continuous casting strands originates from the uneven distribution of carbon between the solid and liquid phases during solidification. The initially solidified solid phase （dendrites） has a lower carbon content， causing excess carbon to enrich the liquid phase at the solid-liquid interface front and form localized high-carbon zones. This defect persists throughout the entire process from hot rolling to product service， severely deteriorating material processability， inducing banded structures and heat treatment defects， and significantly reducing the mechanical properties and service life of the final product. This study systematically investigates the carbon macrosegregation behavior of low-carbon alloy steels （20CrMo， 3130）， medium-carbon alloy steels （4142， 45）， and high-carbon alloy steel （GCr15） under different continuous casting process parameters （superheat， casting speed， mold electromagnetic stirring （M-EMS）. The research defines optimized process windows for typical steel grades： for low-carbon steel 20CrMo， a superheat of 20 ℃–25 ℃， casting speed ≤1.60 m/min， and M-EMS current of 195A–205 A are recommended； for medium-carbon steel 4142SR， a superheat of 20 ℃–28 ℃， casting speed of 1.58m/min–1.62 m/min， and M-EMS current of 200A–208 A are recommended； for high-carbon steel GCr15， a superheat of 18 ℃–25 ℃， casting speed ≤1.16 m/min， and M-EMS current of 195A–202 A are recommended. The main results are as follows： 1） Effect of carbon content： As the carbon content of the steel grade increases， the proportion of negative segregation from the strand center to the 1/2 radius region decreases from 45% to 28%， and the inner arc/outer arc negative segregation ratio decreases from 1.5 to 1.24. 2） Effect of superheat： With constant casting speed and electromagnetic stirring intensity， the tundish superheat within the range of 20 ℃–30 ℃ yields the optimal （lowest） carbon segregation index. 3） Effect of electromagnetic stirring： Within a specific magnetic field intensity range， enhancing M-EMS effectively reduces the fluctuation range of the carbon segregation index. 4） Effect of casting speed： Increasing the casting speed leads to a significant rise in the carbon segregation index of the strand. This study quantitatively reveals the influence of key continuous casting parameters on carbon macrosegregation in alloy steels with different carbon contents. It provides a direct basis for effectively controlling carbon macrosegregation in industrial production by optimizing parameters such as superheat， electromagnetic stirring intensity， and casting speed， with particular emphasis on the need for targeted process optimization based on the steel grade's carbon content.关键词：Carbon Segregation;Electromagnetic Stirring （EMS）;Casting Speed;Superheat15|16|0更新时间：2026-01-10
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