最新刊期
卷 47 ， 期 3 ， 2026
- 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 Models43|68|0更新时间：2026-05-12
Overview
- 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 Design30|30|0更新时间：2026-05-12
- 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 Recrystallization19|27|0更新时间：2026-05-12
- 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;Wear16|61|0更新时间：2026-05-12
- 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 Process14|18|0更新时间：2026-05-12
Product Research and Development
- 摘要：This study investigates the vacuum arc remelting （VAR） process of a
- 摘要：This paper investigates the process of nitrogen alloying in gear steel by bottom blowing nitrogen during refining process （LF and VD） as a substitute for nitrogen-containing alloy cored wires， focusing on solving the core challenge of stably controlling the nitrogen content in molten steel. Through thermodynamic and kinetic analysis， the influence mechanisms of key factors such as molten steel composition （especially S and O content）， nitrogen partial pressure， nitrogen blowing flow rate and time were elucidated. To achieve stable control of nitrogen content through the following measures：Strictly control the sulfur w［S］ content of the molten steel entering the LF station to ≤ 0.025%， reducing interfacial resistance and enhancing nitrogen pickup efficiency； During the LF refining stage， employ optimized nitrogen partial pressure （0.4 MPa-0.7 MPa） and flow rate 0.9 m³/（min·t）， combined with controlled nitrogen blowing time to manage the initial nitrogen increase.In the VD vacuum treatment stage， the bottom blowing nitrogen process （partial pressure 0.7 MPa， flow 0.6 m³/（min·t）） is flexibly adopted to achieve the fine adjustment and stability of nitrogen content by using the dynamic balance between nitrogen increase and nitrogen removal.Production practice results demonstrate that through the above comprehensive control means， utilizing nitrogen as the stirring gas in both LF refining and VD vacuum treatment enables effective alloying operation， and the final nitrogen content of gear steel grade 20MnCrS5 can be stably controlled within the target range of （100-140）×10-6 . The study also find that the S content in molten steel is the key factor affecting the effect of nitrogen increase by blowing nitrogen in LF， and the lower the S content （w［S］≤0.025%）， the higher the nitrogen increase rate （approximately 6.9×10-6 min-1）.In VD vacuum refining process， nitrogen is used instead of argon， and the coexistence phenomenon of nitrogen increase and nitrogen removal in molten steel exists， which shows the phenomenon of nitrogen increase with an approximate rate of 2.19×10-6 min-1.关键词：Gear steel;Refining;Nitrogen;20MnCrS5;Stable Control26|46|0更新时间：2026-05-12
- 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 Preheating14|52|0更新时间：2026-05-12
- 摘要：The aluminum increase and titanium loss during ESR of high Ti low Al R-26 alloy is a typical technical issue.Thermodynamic models of molten slag and slag-metal reaction were established to analyze the activities of slag components and their relationship with metal composition， and then slag optimization scheme were proposed and verified through process trial. The results indicated that， the model effectively calculated the variation of component activity in slag. The unstable oxides in slag， including 0.35%w［SiO2］ and 0.14%w［FeO］， cause the oxidation reaction of titanium. The reaction of Ti with Al2O3 at high temperature can proceed spontaneously， as the key that caused changes in the content of Al and Ti in ingot. With TiO2 added into the slag， the equilibrium Al content significantly decreased， thereby w［TiO2］ needs to be higher than 4% for w［Al］<0.25% at 1 873 K. In addition， the equilibrium Al content increased with the increase of CaO and Al2O3， and decreases with the addition of MgO in the slag. A recommended optimization plan "4% w［TiO2］， 2%-4% w［MgO］， 10%-15% w［CaO］ and w［Al2O3］ each， and CaF2 balance" was proposed based on the ternary purification slag CaF2-Al2O3-CaO. Through the verification of process trials， the variation trend of Al content in the ingot with slag conditions and Ti content conformed to the theoretical analysis， proving that this study could effectively guide the ESR process to achieve the control of titanium loss and aluminum increase.关键词：Alloy;Electroslag Remelting;Aluminum and Titanium;Slag;Process Control34|31|0更新时间：2026-05-12
- 摘要：Slag entrainment compromises ingot quality. Investigating its behaviour during ingot casting is crucial for enhancing product quality. In this study， a 9 t octagonal ingot was selected as the research object and a VOF（Volume of Fluid） multiphase flow model was established to systematically analyze the behaviour of molten steel filling flow fields， variations in Weber number， liquid surface fluctuations， and steel-slag interface behavior under different casting speeds. The results show that a casting speed of 20 kg/s represents the critical maximum casting speed at which slag entrainment occurs in this ingot. Below this speed， the Weber number near the central flow stream remains lower than the critical value， indicating stable flow patterns and mild surface fluctuations， with a central wave height of 0.06 m. The steel-slag interface remains stable， and slag entrainment does not occur. When the casting speed exceeds this threshold， the Weber number near the central flow stream exceeds the critical value， reducing flow stability. The height of the central surface hump and the turbulent kinetic energy of the central jet increase， raising the central wave height to about 0.08 m. The residence time of slag eye becomes longer， intensifying surface fluctuations and destabilizing the steel-slag interface. Consequently， the residual slag phase content in the molten steel increases sharply， with the residual rate rising from 0% at 15 kg/s to 74.3% at 25 kg/s.关键词：Ingot Casting;Casting Speed;Liquid Surface Fluctuations;Slag Entrai-nment Behaviour;Numerical Simulation17|35|0更新时间：2026-05-12
- 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;Superheat29|37|0更新时间：2026-05-12
Smelting and Solidification
- 摘要：The microstructure and mechanical properties of a new 2 200 MPa grade ultra-high strength steel after different austenitizing temperature treatments were investigated through mechanical tests， optical microscopy （OM）， scanning electron microscopy （SEM）， and other methods.The results showed that the strength and toughness and plasticity first increased and then decreased with the increase of austenitizing temperature. At 940°C austenitizing temperature， the optimal strength-toughness balance was achieved， with a tensile strength of 2 222.5 MPa， a yield strength of 1 725.5 MPa， an elongation after fracture of 11%， a reduction of area of 42.5%， and an impact energy of 51.05 J.At lower austenitizing temperatures， the impact fracture morphology was primarily characterized by hole-aggregating toughness dimples with fine grain size.Fine secondary phases （with a diameter of only 0.75 µm） were observed on the fracture surface. Based on phase diagram calculations and EDS（energy spectrum analysis）， the secondary phase was identified as M23C6.With increasing austenitizing temperature ， the morphology of the impact fracture surface transitioned to a combination of dimples and quasi-cleavage， accompanied by the disappearance of secondary phases and gradual coarsening of grains.关键词：Austenitizing Temperature;2 200 MPa Grade Ultra-high Strength Steel;Mechanical Properties;Microstructure59|43|0更新时间：2026-05-12
- 摘要：The network carbides in the core of GCr15 bearing steel bars are a critical factor affecting the fatigue life and service reliability of high-end bearings. Insufficient cooling capacity within the 700–900 ℃ range after rolling significantly promotes the precipitation of network carbides at grain boundaries， while traditional physical temperature measurement methods cannot accurately to capture the temperature variation patterns within the core. To address this， a full-process simulation model for the hot continuous rolling and cooling of 40 mm bars was established using DEFORM-3D software. By precisely calculating heat transfer coefficients for air and water cooling， the simulated surface temperatures achieved high consistency with actual measured temperatures. A multi-stage water cooling process was proposed. Results indicate that the optimized cooling system rapidly reduces the core temperature from 860 ℃ to 639 ℃， effectively avoiding the temperature range where network carbide precipitation occurs， while simultaneously controlling the surface re-reddening temperature below 609 ℃. Experimental verification confirms that under this optimized water-cooling process， carbide precipitation in the core of GCr15 bearing steel bars is significantly reduced.关键词：GCr15 Bearing Steel;Multi-stage Water Cooling;Network Carbides;Core Cooling;Core Temperature27|29|0更新时间：2026-05-12
- 摘要：This study systematically investigates the influence of soft reduction （with/without， 5 passes with a total reduction of 7 mm） and subsequent heat treatments-salt bathing （440°C and 500°C） and tempering （630°C and 680°C）-on carbon/silicon segregation in high-silicon graphited steel billets and its effects on microstructure evolution and graphite precipitation behavior in wire rods. Industrial continuous casting， heat treatment trials， and characterization tools （metallographic microscopy， SEM） were employed. Results demonstrate that implementing soft reduction significantly improves centerline quality of free-cutting graphited steel billets， effectively reducing carbon and silicon segregation at the billet core.Bainite transformation significantly occurred in both non-soft-reduction and soft-reduction strand hot-rolled wire rods during salt baths at 440°C and 500°C. Furthermore， acicular bainite was more readily formed under conditions of high carbon and silicon content in the rod thickness center and at lower salt bath temperatures.The heat treatment process employing a 440°C salt bath followed by tempering at 680°C can effectively increase the number of graphite nucleation sites during the tempering process of free-cutting graphited steel. Building upon this optimized process， increasing the base carbon and silicon content can accelerate and promote the massive nucleation of graphite particles in the size range ≥1 μm but <3 μm during tempering.After undergoing the 440°C salt bath and 680°C tempering treatment， the graphite particle densities in the thickness center of the non-soft-reduction and soft-reduction rods were relatively high， reaching 24，434 particles/mm2 and 32 675 particles/mm2， respectively. The graphite particle sizes in both cases were predominantly within the ≥1 μm to <3 μm range.关键词：Soft-reduction;High Silicon Graphited Steel;Salt Bath Temperature;Tempering Temperature;Graphite Particles14|22|0更新时间：2026-05-12
- 摘要：In view of the complex service environment of the electrode in the Joule furnace for vitrification， to ensure the microstructural uniformity and performance stability of the 690 alloy electrode material， the effects of isothermal heat treatment temperatures （600 ℃， 800 ℃， 1 000 ℃， 1 100 ℃， and 1 200 ℃） on the microstructure including austenite grain size and carbide dissolution， as well as mechanical properties of the alloy were investigated using testing methods such as optical microscopy （OM）， scanning electron microscopy （SEM）， and room-temperature tensile test.The results show that the austenite grain size of the 690 alloy increases with the rise of temperature. From 600 ℃ to 1 000 ℃， the grain growth is slow， and the average grain size increases from 48.13 μm to 64.37 μm. At 1 100 ℃， the grains coarsen sharply， with the average size increasing to 225.21 μm， and further coarsening to 254.72 μm at 1 200 °C.The isothermal temperature significantly affects the composition， quantity， and distribution of the second phase. Between 600 ℃ and 800 ℃， a large number of second phases are distributed at the grain boundaries and within the grains of the alloy； the main phase at the grain boundaries is M₂₃C₆， while the dispersed granular second phases are a mixture of M₂₃C₆ and Ti（CN）. When the temperature exceeds 1 000 ℃， the second phase at the grain boundaries basically disappears， and only a small amount of granular second phase remains in the matrix， and the titanium content decreases.Temperature variation mainly affects the tensile strength and reduction of area of the alloy. The tensile strength decreases with increasing temperature； when the temperature rises from 1 000 ℃ to 1 100 ℃， the tensile strength drops significantly from 638 MPa to 587 MPa， which is mainly attributed to the sharp coarsening of grains leading to a reduction in the grain refinement strengthening effect. The reduction of area shows a "first increase then decrease" trend， reaching a peak value of 78.5% at 1 000 ℃. This study provides an experimental basis for the optimization of the solution treatment process of the 690 alloy used in the electrodes of joule furnaces for vitrification.关键词：690 Alloy;Isothermal Heat Treatment;Grain Size;Secondary Phase;Tensile Properties15|35|0更新时间：2026-05-12
- 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 Steel21|38|0更新时间：2026-05-12
- 摘要：This article systematically investigates the effects of different heat treatment processes on the hardenability of 20CrMnTiH gear steel with w［B］ content of 0.0018% and 0.0051%. By theoretically calculating the solubility product in the Ti-Al-B-N system， it was confirmed that boron in the hot-rolled bars used in the experiment exists in the effective form. The study compared the microstructure and end quenching hardness curves of hot-rolled state， spheroidized annealed state at two different temperatures （600 ℃ and 650 ℃）， and normalized state. The results indicate that the heat treatment process significantly affects the hardenability of steel， and the order of performance is： normalized state>hot-rolled state>spheroidized annealed state （600 ℃）>spheroidized annealed state （650 ℃）. It is analyzed that this difference is mainly due to the solid solution behavior of boron in cementite. During high temperature spheroidizing annealing process， more boron atoms dissolve into cementite， and in the subsequent austenitization process， this part of boron is difficult to fully dissolve back to the austenite grain boundaries in a short time to play its role in improving hardenability， resulting in a decrease in hardenability. This study clarifies that solid solution boron in cementite is a key factor affecting the hardenability of boron containing gear steel after heat treatment， providing important basis for optimizing the heat treatment process to fully utilize the performance advantages of boron steel.关键词：20CrMnTiH Steel;Boron;Heat Treatment;End Quench;Hardenability13|29|0更新时间：2026-05-12
- 摘要：A numerical simulation model describing the steel quenching process was developed using the finite element software COMSOL Multiphysics 6.3. The temperature and microstructure field evolution of CM690 anchor chain steel during Jominy end-quech test were systematically simulated， and the simulation results were verified through experiments. The results show that the developed model can accurately predict the temperature distribution and microstructure evolution of the test steel during Jominy test. During Jominy end-quench test，the specimen exhibits quasi- one-dimensional heat transfer characteristics ， and the temperature field changes are mainly influenced by the comprehensive heat transfer coefficient at the interface. As the distance from the quenched end increases， the cooling rate gradually decreases， resulting in a gradient distribution of the microstructure： the martensite content gradually decreases and is mainly concentrated in the 0 mm ~ 20 mm range； bainite appears in the area from 9 mm to 40 mm away from the quenching end； pearlite is distributed in the 70 mm to the top range； and ferrite forms in the 25 mm to the quenching top. Furthermore， the observed microstructure of the dilatometric specimens at different distances from the quenched end is highly consistent with the simulation predictions. The Vickers hardness values measured for Jominy test specimen and the dilatometric specimen also show the same trend of change， further verifying the reliability and applicability of the model.关键词：CM690 Anchor Chain Steel;Jominy Test;Numerical Simulation;Temperature Field;Microstructure Field13|42|0更新时间：2026-05-12
Forming and Phase Transition
- 摘要：The number， size， chemical composition and morphology of inclusions in continuous casting billet samples were analyzed using SEM and bulk sample electrolysis for high strength OCTG steel. The results show that the micro inclusions and large inclusions in the continuous casting billets are significantly higher than the stable casting state in the biginning casting stage of the tundish.T.O content in the billet is less than 10×10-6， and the macro inclusion content in the billet is less than 1.5 mg/10 kg in the stable casting stage. The seamless steel pipes produced from round billets at casting start stage exhibit significant fluctuations in impact energy， with the maximum impact energy being 1.4 times the minimum. The impact energy decreases as the T.O content in the steel increases.Samples with lower impact energy show a higher area fraction of inclusions， the inclusion area fraction in the 37 J sample is 2.1 times that of the 53 J sample. Nonmetallic inclusions in the steel are the primary cause of the impact energy fluctuations.关键词：High Strength Casing;Non-metallic Inclusion;Impact Toughness;Bulk Sample Electrolysis39|27|0更新时间：2026-05-12
Application and Service
- Technical support is provided by Beijing Founder electronics co., LTD 鄂ICP备2022000839号
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
- Total Visits：53391 Visits Today：54
0