最新刊期
卷 47 ， 期 2 ， 2026
- 摘要：With the rapid development of energy infrastructure， shipbuilding and promotion of China’s “the Belt and Road” strategy， the demand for medium and heavy plates that widely used for containers/pressure vessels， ships， pipelines， etc.，is growing increasingly， and their mechanical properties are also increasingly demanding. Low temperature impact toughness is one of the most important performance indicators. Due to the large thickness， the low temperature toughness value is usually discrete and fluctuating， which is one of the main issues for medium and heavy plate products. In this paper， the main rolling technologies， key manufacturing technologies and mechanical and process performance requirement for medium and heavy plate were reviewed firstly. With the increasing demands for usage and advancements in production equipment and technologies， the requirements for the size and mechanical properties of medium and heavy plates are becoming larger and higher， respectively. Currently， the maximum thickness of heavy plate products can reach 700 mm， and the tensile strength of stably produced high-performance wear-resistant steel plates has reached up to 1 900 MPa， the 1 300 MPa level high strength mechanical steels has also been supplied at the market. And then， the research progress on low temperature toughness of medium and heavy plates， including mechanism， influence factors， and improvement methods， were summarized. The main reason of low temperature toughness fluctuations is the heterogeneity of the microstructures. Improving the homogeneity of the microstructures through composition and process optimization can mitigate the fluctuation of low-temperature impact. Finally， the insufficient aspects for the research on low temperature impact toughness of medium and heavy plate and the future development direction of the technology were pointed out.关键词：Medium and Heavy Plate;Producing Technology;Mechanical Property;Low Temperature Impact Toughness5|0|0更新时间：2026-03-03
Overview
- 摘要：Bainitic non-quenched and tempered steel has broad application prospects in the field of high-strength and tough structural components. On the basis of traditional Mn-Cr series bainitic non-quenched and tempered steel， a new type of bainitic non-quenched and tempered steel has been developed by adding small amounts of Ni and V elements. The synergistic control of multiple elements in steel gives the potential performance advantages of the material， but it is necessary to develop a reasonable forging process to activate these potentials. The high-temperature compression tests under different temperatures （950 ℃-1 150 ℃） and different strain rates （0.01 s⁻¹-10 s⁻¹） were carried out on the Gleeble-3500 thermal simulation testing machine to study the hot deformation behavior of this bainitic non-quenched and tempered steel. Furthermore， an Arrehenius constitutive equation containing the Z parameter was established， which can well predict its high-temperature flow behavior. In addition， based on the dynamic material model and microstructure verification， a hot working diagram under a true strain of 0.7 was established. The obtained optimal hot working process range was as follows， the deformation temperature range was 1 050 ℃-1 150 ℃， and the strain rate range was 0.01 s⁻¹-0.22 s⁻¹. The strain rate of hot forging should be lower than 0.22 s⁻¹ to avoid the flow instability phenomenon during the deformation process.关键词：Non-quenched and Tempered Steel;Thermal Compression;Constitutive Equation;Thermal Processing Map;Microstructure15|2|0更新时间：2026-03-03
- 摘要：At present the commonly used mining chain steel 23MnNiMoCr54 contains high valuable elements such as Ni and Mo， so the cost is high， which limits its wide application.In this study， a new type of economical mining chain steel was designed by reducing the contents of Ni and Mo， regulating the contents of Mn and Cr， and adding Nb microalloying. Through mechanical property tests， hardenability tests， uniform corrosion and stress corrosion experiments， combined with chain performance tests， the performance differences between the new steel and 23MnNiMoCr54 steel were compared and analyzed. The results show that the mechanical properties and hardenability indexes of the new steel meet the standard requirements. In simulated mine water， its uniform corrosion rate has no significant difference from that of the control steel， while the stress corrosion sensitivity factor and hydrogen embrittlement coefficient are better， and the hydrogen-induced cracking resistance is improved. The chain made of the new steel has a breaking load of 1 710 kN and a fatigue life of more than 6.7×10⁴ cycles， meeting the C-level chain standard in GB/T 12718-2009.关键词：Mining Chain;Corrosion;Hydrogen Induced Cracking;Mechanical Properties;Low Cost11|0|0更新时间：2026-03-03
- 摘要：To develop high-quality H13 hot work die steel continuous-casting billets and address quality issues such as segregation and shrinkage cavities， a process involving converter + LF + RH + continuous casting + rolling was adopted. By employing dual-block slide gate in the converter， full-process diffusion deoxidation during refining， and controlling the basicity of refining slag， as well as utilizing full-process protective casting and pulse magnetic oscillation （PMO） solidification homogenization technology and other auxiliary methods during continuous casting， industrial production of H13 hot work die steel was successfully achieved on a
Product Research and Development
- 摘要：To address the issue that high temperatures and significant furnace gas variations during converter steelmaking substantially affect the characteristics of supersonic oxygen jets， while research on the changing patterns of jet characteristics across different smelting stages remains limited， the effect of furnace gas composition on supersonic oxygen jet characteristics in converter steelmaking under different temperatures was investigated through CFD numerical simulation.The results indicate that at the same furnace gas concentration， the core length of the oxygen lance jet at high temperature （1 873 K） is 2.6 times longer than at room temperature （298 K）. The length of supersonic zone increases linearly with rising CO concentration in the furnace gas， with a more pronounced growth rate at elevated temperatures. A 20% increase in CO concentration extends the core length by 0.048 m at room temperature and by 0.126 m at high temperature. The increase of CO concentration enlarges the effective impact area of the oxygen jet， with a maximum increase of 11.6% at room temperature and 3.1% at high temperature. At room temperature， the effective impact area initially increases and then decreases as the lance height rises， whereas it continues to expand under high-temperature conditions. During the mid-blowing stage， higher CO concentration and ambient temperature contribute more effectively to slowing jet attenuation and expanding the effective impact area.关键词：200 t Converter;Five-hole Oxygen Lance;Numerical Simulation;Jet Attenuation;Furnace Gas Composition6|0|0更新时间：2026-03-03
- 摘要：Precise control of the endpoint phosphorus content in converter steelmaking is a core aspect for enhancing steel quality and smelting efficiency. This study innovatively integrates Uniform Manifold Approximation and Projection （UMAP）， Grey Wolf Optimization （GWO）， and Deep Neural Network （DNN） technologies to construct a multimodal intelligent prediction model for 42CrMo steel. The UMAP algorithm is employed to perform nonlinear dimensionality reduction on high-dimensional smelting parameters （such as temperature， oxygen lance height， slag basicity， etc.）， effectively extracting key features. The GWO algorithm is used to optimize the initial weights and hyperparameters of the DNN， significantly improving the model's convergence speed and stability. The experiments are conducted based on actual production data from 20eats in a steel plant. Compared with the BP neural network， standard DNN， and GWO-DNN models， the UMAP-GWO-DNN model achieves hit rates of 86.7% and 95.4% in error ranges of ±0.001% and ±0.002%， respectively， and the root mean square error （RMSE） is reduced by 23.6%.Industrial validation shows that this model reduces the standard deviation of endpoint phosphorus content fluctuations by 41%， stabilizing the mean value from 0.001 2% to 0.000 9%， successfully achieving the "narrow window" control target. This study provides a scalable technical path for the digital upgrade of converter smelting processes.关键词：Endpoint Phosphorus Content;Converter Steelmaking;Deep Neural Network;Prediction Model;Industrial Application6|0|0更新时间：2026-03-03
- 摘要：To improve the cleanliness and castability of IF steel， this study was conducted by 260 t RH vacuum furnace facility at Hanbao Steelmaking Plant ， HBIS Handan Iron and Steel Group Co. ， Ltd. Using 16-heats H-OLTB converter process as a case study， researchers employed sampling techniques， inclusions scanning electron microscopy （SEM）， and data analysis to evaluate endpoint carbon content， decarburization duration，top slag， and inclusion quantity/size under both free-decarburization and forced-decarburization modes during IF steelmaking. Statistical analyses were performed based on the mass fractions of top slag TFe and TO at RH refining completion， along with inclusion quantity and size metrics. The findings systematically demonstrate how decarburization modes influence top slag oxidation characteristics and molten steel purity. The results show that the free decarburization mode outperforms the forced decarburization mode in terms of decarburization time and end-point carbon content， with the free decarburization mode reducing decarburization time by an average of approximately 3.15 minutes. The mass fractions of T.Fe and FeO in the top slag under the forced decarburization mode are lower than those under the free mode， with values of 5.68% and 5.45% respectively for the forced mode， compared to average values of 7.26% and 6.84% for the free mode. The number of inclusions in IF molten steel is fewer under the forced decarburization mode， with the number of inclusions ≤15 microns per unit area ranging from 16.2 to 23.4 for the free mode and 10.6 to 14.4 for the forced mode. Overall， In the H-OLTB converter， the initial oxygen content at the inlet of the RH furnace is controlled at （286-408）×10⁻⁶. When refining IF steel in the RH furnace using the forced decarburization mode， the molten steel has higher cleanliness.关键词：IF Steel;Free Decarbonization;Forced Decarbonization;Cleanliness5|1|0更新时间：2026-03-03
- 摘要：To address fish-like substances caused by TiN inclusions during high-Ti steel continuous casting process， five potential mold slags for high titanium steel were designed. The TiN absorption behaviors and mechanisms by various mold slags were investigated through integrated in-situ observation， rotating cylinder tests， and thermodynamic calculations. In-situ observations revealed that the above five types of mold slags would react with TiN to produce bubbles ， with CaO-SiO2-Al2O3 （CSA）-based slag showing the strongest reactivity， followed by CaO-SiO2-Al2O3-BaO （CSAB）-based slag. Rotating cylinder tests demonstrated slowed TiN absorption rates of each mold slag was slow ， where CSA mold slag achieved the fastest rate of 3.00×10-3 mm/min at 1 520 ℃， followed by CSAB mold slag （2.46×10-3 mm/min）. This was consistent with the rules of in situ observation. Electron microscope observation， thermodynamic calculation and composition change before and after absorption of the reaction interface showed that the absorption rate of TiN by the protective slag was negatively correlated with the thickness of the boundary layer of the reaction.TiN primarily reacted with Na2O oxidizer in slags， with CSA slag exhibiting the highest Na2O activity and optimal absorption capacity. Its absorption mechanism is as follows： TiN reacts with the oxidizing components in the slag to generate TiO2， and TiO2 enters the mold slag through diffusion dissolution. Therefore， the activity of the oxidizing components in the mold slag can be increased to absorb and remove TiN after oxidation.关键词：High Titanium Steel;TiN Inclusions;Mold slag;Absorption Behavior7|0|0更新时间：2026-03-03
- 摘要：To effectively improve the macrosegregation of continuous casting small square billets based on waste slag steel smelting， a multiphase solidification model that can directly couple the behaviors of the melt flow， microstructure evolution， and solute transport in the whole continuous casting process was established. Taking the continuous casting small square billet with a cross section of 160 mm × 220 mm for 25MnSiV as an example， when the superheat degree decreases from 45 K to 15 K， the width of equiaxed crystal in the center of continuous casting small square billet increases from 40 mm to 46 mm， and the carbon macrosegregation degree in the billet center at the end of solidification decreases from 1.23 to 1.16. Therefor，for improving the macrosegregation， the low superheat casting process should still be used as far as possible in the continuous casting small square billet production based on waste slag steel smelting. In addition， if the low superheat is maintained during the casting of small square billet，the mechanical reduction near solidification end could be further applied， and the reduction region could cover the solute enrichment zone （fs = 0.42-1.0）， the macrosegregation defects at the solidification end of billets can be better improved.关键词：Continuous Casting;Small Square Billet;Superheat Degree;Macrosegregation;Mechanical Reduction21|8|0更新时间：2026-03-03
- 摘要：To investigate the mechanism by which optimizing the ladle bottom structure improves steel cleanliness， this study focuses on slag entrapment behavior and adopts the critical vortex height as the key indicator for evaluating the tendency of slag entrainment. By analyzing the water model data， three parameters including step volume， steel throughput and the distance from the nozzle to the step， were selected to establish empirical formulas correlating them with the critical vortex height. Additionally， a formula was fitted to describe the relationship between step volume and the remaining molten steel volume in the ladle， providing a theoretical basis for structural optimization design. Based on this foundation， a novel sloped step-type ladle bottom structure was designed. The ladle bottom was optimized into an inclined plane sloping toward the nozzle， with the sloped section ranging in height from 260 mm to 220 mm， a gradient of 2°， and a total slope height of 70 mm. This optimized bottom structure is primarily applicable to ladles with capacities between 150 tons and 300 tons. At the same time， industrial trials were conducted to verify the effectiveness of the design. An automatic scanning electron microscope was used to analyze inclusions in both the tundish and slab before and after optimization. The results show that after optimization， the total oxygen content （w［T.O］） in the tundish steel sample decreased from 40×10⁻⁶ to 27×10⁻⁶， and the total nitrogen content （w［T.N］） dropped from 87×10⁻⁶ to 61×10⁻⁶. The number density of inclusions larger than 2 μm decreased from 28/mm² to 5/mm².In the slab， the number of 10 μm–14 μm inclusions was significantly reduced， with the maximum size decreasing from 53 μm to24 μm. The area fraction and number density of inclusions showed the most notable reduction at the slab thickness center.The optimization of the ladle bottom structure can effectively enhance molten steel cleanliness by controlling slag entrapment at the end of casting and suppressing the migration and accumulation of inclusions， demonstrating significant engineering application value.关键词：Continuous Casting Slab;Ladle Structure;Vortex;Residual Volume of the Molten Steel12|1|0更新时间：2026-03-03
- 摘要：As a typical defect formed during the ingot filling process， the slag entrapment directly affects the final quality of the steel ingot. The shape of the nozzle at the bottom of the ingot mold is a key factor influencing the flow of molten steel and the behavior of slag entrapment，in order to explore the influence law of the shape of the nozzle on the slag entrapment behavior， this paper， based on the Fluent multiphase flow model， systematically studies the influence of the inlet angles of the nozzle （5°， 15°， 25°） on the behaviors such as the flow field and slag droplet capture during the filling process of a 3.1 t steel ingot by taking into account the interactions among the three phases of molten steel， mold powder， and air as well as the solidification behavior during the filling process of molten steel. The results show that： in the initial stage of the filling process， the solidified shell in the tail region of the steel ingot is relatively thin， and the internal fluidity inside the molten steel is good， so the slag droplets will quickly float up to the slag layer. With the increase of the filling height， the change of the inlet angle of the nozzle will significantly affect the flow pattern of the molten steel. The larger the inlet angle is， the more the main stream of the molten steel will deviate towards the outer sidewall. For this type of ingot， when the inlet angle of the nozzle is 5°， the internal eddy current inside the molten steel is always located in the area near the liquid surface where the solidified ingot shell has not been formed. The flow pattern and the solidification process are more conducive to suppressing the occurrence of slag entrapment.This study can offer references and guidance for the design of nozzle shapes in bottom-pouring mold casting production.关键词：Steel Ingot;Multiphase Flow;Inlet Angle of the Nozzle;Slag Entrapment Defect10|2|0更新时间：2026-03-03
- 摘要：The submerged nozzle is the guiding part of molten steel flow in continuous casting mold. Optimizing the structure of submerged nozzle and improving the flow state of molten steel are of great significance for producing high quality cast billet.The flow field in the continuous casting mold with a size of 230 mm×1 650 mm wide and thick slab in a steel plant in Henan Province was systematically studied， and a numerical simulation was conducted using FLUENT software. In view of the violent fluctuation of molten steel level in the mold during production， a new flat nozzle is adopted to analyze the influence of the replaced submerged nozzle on the flow field of molten steel in the mold.Research findings indicate that substituting the flat nozzle led to a more favorable flow pattern of the molten steel within the mold. Before the replacement， the free steel liquid surface velocity in the circular nozzle mold fluctuated greatly， and the velocity of the steel-slag interface within the range of 0 m-0.3 m from the nozzle fluctuate greatly and reach a maximum of 0.3 m/s. It caused severe fluctuations in the steel liquid surface and surface slag inclusion behavior， seriously affecting the quality of the cast billet. In addition， the turbulent energy of a flat nozzle is reduced by 50% compared to a circular nozzle. Which significantly reduce the risk of nozzle clogging and increasing the service life of submerged nozzles. Comprehensive analysis shows that the new flat nozzle is more suitable for wide and thick plate site than the circular nozzle.Finally， the process parameters of the flat nozzle were simulated， and the results showed that when the nozzle was immersed at a depth of 125 mm， pulled at a speed of 0.8 m/min， and tilted at an angle of 15 °， a relatively ideal flow field shape of the mold could be obtained. This provides the best process plan for the use of this new nozzle and provides reference and guidance for the steel and iron enterprise to formulate reasonable process parameters.关键词：Continuous Casting Mold;Submerged Nozzle;Structural Optimization;Flow Field Regulation;Process Parameters5|0|0更新时间：2026-03-03
- 摘要：To address the internal quality issues of 1 400 mm × 300 mm thick 22MnB5 steel slabs， a dynamic mesh mechanical soft-reduction model for slab solidification was developed. This model integrates multiple physical fields， including fluid flow， heat transfer， solidification， and solute transport， to analyze the effects of reduction amount and reduction zone on slab internal quality. The results show that mechanical soft reduction can effectively mitigate centerline segregation， and the improvement becomes more pronounced with increasing reduction amount. In particular， when a 10 mm reduction is applied， centerline segregation is significantly alleviated， with a notable decrease in the segregation ratio. Furthermore， the selection of reduction position is critical. Under a casting speed of 1.0 m/min and a superheat of 20 °C， applying reduction in the region 14 m-18 m below the mold meniscus， where the solid fraction is 0.05-0.45， exacerbates segregation. Conversely， when reduction is applied in the region 16-20 m below the meniscus， corresponding to a solid fraction of 0.20-0.95， solute transport is promoted， thereby improving segregation in the slabs.关键词：Steel Plate;Continuous Casting;Mechanical Reduction;Segregation;Numerical Simulation;Macro Test6|0|0更新时间：2026-03-03
Smelting and Solidification
- 摘要：The high nitrogen martensitic stainless bearing steel was tempered at 400 ℃ - 600 ℃， and its mechanical properties such as hardness， strength and toughness were tested. The microstructure was characterized by optical microscope， SEM and TEM. The effects of high temperature tempering on its mechanical properties and microstructure were systematically studied. The test results show that， with the increase of tempering temperature， the hardness and strength of the material increase first and then decrease， and the impact performance continues to increase. When tempered at 500 ℃， the hardness and tensile strength reach the maximum values， which are 60.8 HRC and 2 360 MPa， respectively. The microstructure analysis shows that， when the tempering temperature is no higher than 500 ℃， the sample is mainly tempered martensite structure with a small amount of secondary-phase particles. After more than 500 ℃， the martensite structure gradually transforms into tempered sorbite， and the number and size of the secondary-phase particles increase. The size and number of secondary-phase particles tempered at 500 ℃ and 600 ℃ were counted in the same area. It is found that the total number and area ratio of secondary-phase particles tempered at 600 ℃ are much higher than those tempered at 500 ℃， and the proportion of large-sized particles increase significantly. The secondary-phase M23C6 and Cr2N precipitates in the samples tempered at 500 ℃ and 600 ℃. These secondary-phase particles grow densely at 600 ℃， resulting in a decrease of secondary-phase strengthening effect， which is attributed to the considerable decreases in strength and hardness.关键词：High Nitrogen Martensitic Stainless Bearing Steel;High Temperature Tempering;Mechanical Properties;Microstructure;Secondary-phase6|0|0更新时间：2026-03-03
- 摘要：Through Rockwell hardness testing， EBSD， XRD， TEM characterization and other methods， the differences in hardness and microstructure between German and domestic 23MnNiMoCr54 chain link steels were revealed. The results show that the German chain link has higher residual elements Cu and N due to the all-scrap-electric furnace smelting process， with an average hardness of 41.32HRC and a range of only 0.85HRC， showing the highest average hardness and the smallest hardness fluctuation.The high N content leads to an increase in the density of precipitated phases， which refines the original austenite grains to 13.66 μm through the Zener pinning effect and increases the proportion of high-angle grain boundaries to 38.3%. These factors synergistically hinder the movement of dislocations， resulting in the highest hardness of the German chain link.During the medium-frequency quenching process， after the surface temperature of the workpiece exceeds the Curie temperature， the surface eddy current density increases and the austenitization temperature becomes higher， leading to the coarsening of the original austenite grains and an increase in dislocation density at the edges of both German and domestic chain links. This study provides a theoretical basis for the upgrading of smelting processes and heat treatment technologies for domestic mining chain links， and it is of great significance to promote the process of domestic substitution of key parts and components of mining equipment.关键词：23MnNiMoCr54;Round Chain Links for Mines;Microstructure;Hardness;Grain Size22|3|0更新时间：2026-03-03
- 摘要：The effects of different solid solution temperature on the recrystallization behavior of as-forged high-quality GH4 738 superalloy were investigated by optical microscopy， field emission scanning electron microscopy （FE-SEM） and mechanical property tests. The results indicate that complete static recrystallization occurs in the as-forged high-quality GH4 738 superalloy during solid solution treatment at 1 040 ℃. When the temperature is lower than 1 040 ℃， the grain size changes slightly， while grain coarsening and poor uniformity occur when the temperature exceeds 1 050 ℃. The primary γ′ phase not only pins grain boundaries to hinder grain boundary migration but also increases deformation stored energy to promote recrystallization. Therefore， solution treatment near the primary γ′ phase solid solution temperature （1 040 ℃） can induce complete static recrystallization and refine grains in high-quality GH4 738 alloy. However， when the holding time is too long （>4 h） or the solid solution temperature is too high （>1 050 ℃）， a large amount of primary γ′ phase redissolves into the matrix， leading to rapid alloy grain growth. The alloy strength first increases and then decreases with the rise of solid solution temperature， and the high-temperature creep life of the alloy is significantly affected by the solid solution temperature.关键词：Solid Solution Temperature;Static Recrystallization;High Quality GH4738 Alloy5|0|0更新时间：2026-03-03
- 摘要：GCr15 bearing steel is the most widely used material for bearing components due to its high strength and hardness. The efficient and convenient preparation of refined and homogenized matrix microstructures has always been a research hotspot for GCr15 bearing steel. In this study， a high-frequency， high-energy electrical pulse technology was used instead of the traditional solid solution process to achieve flash austenitization of GCr15 bearing steel， followed by oil cooling. The mechanical properties and microstructure were characterized and analyzed. The results show that the combined effect of Joule heating and the electron wind effect generated by the electrical pulse current leads to the rapid austenite transformation and carbide dissolution of the material. The hardness， tensile strength and elongation of the sample were 62.3 HRC， 2 356 MPa and 2.5% after the electric pulse heat austenitizing treatment of "voltage 50V - frequency 500Hz - pulse width 50 μs" for 300 seconds. These mechanical properties are superior to those achieved by the conventional heat treatment process. The average carbide size of the samples is 0.46 μm， and the matrix microstructure is uniform， fine， and dispersedly distributed. The research provides an experimental and theoretical basis for the development of new heat treatment processes and microstructure control for bearing steels.关键词：GCr15 Bearing Steel;Electrical Pulse Heat Treatment;Microstructure;Mechanical Properties2|0|0更新时间：2026-03-03
Forming and Phase Transition
- 摘要：The effects of nitrogen-hydrogen mixed atmosphere heat treatment on microstructure and properties of 12Cr ferritic-martensitic steel were studied by electron backscatter diffraction （EBSD） and microhardness （HV0.025）. The results showed that the surface structure of the tube changed due to nitrogen infiltration after heat treatment， and a large amount of martensite was formed near the surface， which decreased with the increased of nitrogen diffusion distance.The nitriding layer would increase the surface hardness of the pipe. The microhardness analysis showed that the hardness value at 20 μm from the surface was 368HV0.025， and the transverse cracks was generated on the surface of the tube in the subsequent cold working deformation process. Based on the thermodynamic library TCFE11 and the kinetic library MOBFE6， a thermodynamic model of heat treatment time and N-directional diffusion distance in the matrix at the boundary was established to study the relationship between nitrogen infiltration and diffusion distance. The results showed that the nitrogen content gradually decreased with the increase of diffusion distance， and the decreasing trend slowed down after the diffusion distance reached 70 μm. By studying the effect of nitrogen infiltration on the microstructure and properties of 12Cr ferritic-martensitic steel， an annealing process for 12Cr ferritic-martensitic steel was developed， the pipe was heated in a hydrogen atmosphere to 860 ℃， holding it for 1 hour， and cooling it using a fan. Production verification confirmed that the surface hardness of the treated pipes was approximately 210HV0.025， meeting the requirements for cold working deformation.关键词：Ferritic-martensitic Steel;Nitriding;Microstructure;Property9|0|0更新时间：2026-03-03
- 摘要：The persistent precipitation phase transformation of S30432 steel after 650 ℃ creep and its effect mechanism on the material's creep ductility were systematically investigated by using analytical methods such as scanning electron microscopy （SEM）， electron backscatter diffraction （EBSD）， and transmission electron microscopy （TEM）， in combination with the results of thermodynamic simulation calculations using Thermo-Calc. Results show that：after 650°C creep， large-sized Nb（C，N） phases exists in the matrix of S30432 steel， which are prone to cracking and forming crack sources under high stress. With the increase of creep time， the precipitates phase M23C6 at grain boundaries and twin boundaries continuously distribute and significantly coarsen， which is conducive to the formation of voids. At 650 ℃and 9 146 h-24 432 h， blockyσphase is generated at the grain boundary. The number of σ phase increases with the prolongation of creep time， accompanied by significant coarsening phenomenon， which promotes the nucleation of micropores and accelerates the germination and propagation of the crack along the grain.The changes in the precipitated phases during these high-temperature long-term processes all have an important impact on the reduction of the creep ductility of S30432 steel at 650°C.关键词：S30432 Steel;Precipitate;Microstructure;Creep Ductility;Nb（C，N） Phase;σ Phase11|0|0更新时间：2026-03-03
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