最新刊期
卷 47 ， 期 5 ， 2026
- 摘要：Die and mould steel is a core foundational material for high-end equipment manufacturing， supporting the forming production of various manufacturing industry chains， including automotive， aviation， aerospace， electronics， medical devices， and general machinery. China has already become the world’s largest manufacturer and market of dies and moulds， and has achieved self-sufficiency in all categories of die and mould steel， transitioning from scale-driven expansion to high-quality development. This paper systematically reviews the progress in research and industrialization of the three major categories—hot-work， plastic mould， and cold-work die and mould steels—covering alloy design， processing technologies， heat treatment regulation， surface treatment and modification， service failure mechanisms， and innovative preparation processes. It identifies shortcomings in microstructural uniformity， consistency， and stability； innovative material design； surface strengthening treatment； and digital-intelligent R&D and production. Furthermore， it proposes that future efforts should focus on： AI-driven digital-intelligent R&D and whole-process intelligent production control； upgrading of short-process， high-uniformity advanced metallurgical manufacturing technologies； development of integrated composite strengthening techniques that are compatible with the base material； improvement of service failure mechanisms and full-life-cycle evaluation systems； and establishment of an industry-level big-data and intelligent service platform for die and mould steels. These measures are intended to accelerate China’s transformation from a major producer into a global powerhouse in die and mould steel.关键词：Die Steel;Development;Research;Current Status1|0|0更新时间：2026-10-13
- 摘要：Hot-forging die steel is a critical material used in the hot-forging of metal components. It is subjected to harsh service conditions involving high temperatures， high stresses， and repeated thermal cycling， making it prone to failure mechanisms resulting from the coupling of various complex processes， such as thermal wear， thermal fatigue， plastic deformation， and creep. Therefore， the in-service performance of hot-forging die steel directly affects the quality of forgings and production costs， making it imperative to fully understand the evolution of its failure behavior and propose effective strategies for performance enhancement. Addressing this need， this paper reviews research progress on the in-service behavior and failure mechanisms of hot-forging die steels and systematically summarizes four typical performance enhancement strategies—alloy composition optimization， precise control of heat-treated microstructure and properties， surface modification and strengthening， and nanoparticle-reinforced matrix—along with their respective effects. Based on this， the paper summarizes the significant potential of the synergistic application of multiple strategies in extending die life and improving in-service performance； highlights the limitation that a single strengthening strategy cannot fully account for the dynamic evolution of failure behavior under the coupled effects of multiple factors； and notes the current inadequacy of collaborative strengthening design and in-service performance prediction models tailored to actual operating conditions. Finally， the outlook indicates that future research should focus on the organic synergy of various strengthening technologies and the application of artificial intelligence in material design and performance prediction. These two areas mutually reinforce each other and are expected to provide the theoretical foundation and technical pathways for the continuous development of hot-forging die steels toward the goals of longer service life， higher reliability， and greater economic efficiency.关键词：Hot-forging Die Steel;Service Life;Service Behavior;Failure Mechanism;Performance Optimization Strategies2|0|0更新时间：2026-10-13
Overview
- 摘要：In the context of integrated die-casting forming technology for new energy vehicles， a new type of extra-large， highly uniform， high-toughness， and high- isotropy die-casting mold steel GY-DCK20 was developed and produced. The microstructural uniformity of samples taken from different locations and their room-temperature mechanical properties were investigated by characterization methods such as metallographic analysis， SEM analysis， and ASPEX inclusion analysis. The results indicate that the high-cleanliness smelting process （EAF +AOD） → RH → Continuous Casting → PESR effectively controls the content of harmful and gaseous elements. Fine inclusions measuring 2-5 μm account for over 73.4% of the total， with oxides being the primary type. No significant banding segregation was observed in samples taken from different locations； the spheroidized microstructure was well-developed， and carbides were fine and uniformly distributed. The heat-treated hardness after quenching at 1 030 ℃ was approximately 1HRC higher than that at 1 010 ℃， and the steel exhibited better impact performance. During the tempering stage， the secondary hardening peak occurred near 540 °C， primarily due to the precipitation of fine， granular alloy carbides； at 650 ℃， martensite began to undergo recovery and recrystallization， forming equiaxed ferrite grains； at 700 ℃， the lath structure of the martensite disappeared， carbides aggregated along the grain boundaries， and recrystallized grains coarsened significantly. At a service hardness of 44-46HRC， the test steel exhibits a transverse and longitudinal V-notch impact absorbed energy of over 35 J at various locations， with an isotropy ratio of up to 0.97 in the core， demonstrating excellent comprehensive mechanical properties.关键词：Die-casting Die Steel;Non-metallic Inclusions;Microstructural Uniformity;Heat Treatment;Room-temperature Impact Properties1|0|0更新时间：2026-10-13
Product Research and Development
- 摘要：To study the effects of different deoxidation methods on the evolution of inclusions and carbides in Cr12MoV steel， experimental steels smelted by three deoxidation processes （Al deoxidation， Al deoxidation combined with rare earth Ce composite deoxidation， and vacuum carbon deoxidation） were analyzed using scanning electron microscopy-energy dispersive spectroscopy （SEM-EDS） and the OTSInca automatic inclusion analysis system （Oxford Instruments）. The effect of the three deoxidation methods on the mass fractions of total oxygen （T.O） and total nitrogen （T.N）， the number， size， composition and morphology of inclusions， as well as the precipitation characteristics and distribution of carbides in Cr12MoV steel were explored. The results show that at 480 Pa， carbon exhibits stronger deoxidation and denitrification effects than Al and Ce. The mass fractions of T.O and T.N in the as-cast samples can be reduced to 0.000 7% and 0.002 7%， respectively. In the experimental steels produced by single Al deoxidation and vacuum carbon deoxidation， inclusions are dominated by fine Al₂O₃， with number densities of 165/mm² and 95/mm²， and average areas of 0.70 μm² and 0.66 μm²， respectively. After Al deoxidation combined with rare earth treatment， inclusions are mainly Ce₂O₂S， with an inclusion number density of 120/mm² and an average area of 2.0 μm². The participation of Ce in deoxidation reduces the total number of inclusions but increases their size. Carbides in both single Al deoxidation and vacuum carbon deoxidation samples exhibit a fish-bone morphology and distribute continuously along grain boundaries to form a network structure， with area fractions of 12.15% and 12.29%， respectively. In contrast， carbides in the Al deoxidation + Ce treatment sample are fine lamellar or granular， distributing discontinuously along grain boundaries in a chain-like or particulate form without forming a continuous network structure， and the carbide area fraction is 11.70%. Ce treatment can significantly refine carbides， break the continuous network structure and reduce the precipitation amount. Compared with Al deoxidation， vacuum carbon deoxidation has no obvious effect on the morphology and precipitation of carbides. This study suggests that， without considering time， replacing partial Al deoxidation with vacuum carbon deoxidation in the smelting of Cr12MoV steel is feasible. It can purify molten steel and optimize the properties of inclusions without affecting carbide precipitation. Al deoxidation combined with rare earth composite deoxidation has a significant effect on carbide control.关键词：Cr12MoV Die Steel;Inclusions;Carbides;Rare Earth Treatment;Vacuum Carbon Deoxidation71|42|0更新时间：2026-10-13
- 摘要：Through the analysis of the chemical composition and non-metallic inclusions data of sampling experiments using two groups of different remelting slag systems to investigate the effect of electroslag remelting slag systems on non-metallic inclusion in corrosion-resistant die steel FS136， under identical experimental conditions， experiments with the binary（CaF2-Al2O3） and the quaternary（CaF2-Al2O3-CaO-MgO） slag systems showed no significant difference in alloying element loss. Metallographic observation and SEM analysis show that the non-metallic inclusions in FS136 steel are mainly Type D inclusions consist of Al2O3-based granular inclusions. In FS136 steel processed with the quaternary experimental slag system， the Type D non-metallic inclusions were controlled to a rating level of 0.5–1.0. Compared with the binary slag system， the quaternary slag system exhibited better performance in wetting， absorption， and removal. The quaternary slag system can further improve the cleanliness of corrosion-resisant die steel FS136.关键词：FS136 Steel;Corrosion-resistant Die Steel;Electroslag Remelting;Type D Non-metallic Inclusions;Electroslag Remelting Slag System;Burning loss3|0|0更新时间：2026-10-13
- 摘要：Cr12MoV die steel is a typical high-carbon， high-chromium cold-work die steel. Due to its high carbon and chromium content， segregation during the late stages of solidification and the aggregation of eutectic chromium carbides are prone to occur during continuous casting， leading to defects such as surface cracks and localized fractures. Against the backdrop of Cr12MoV Die Stee continuous casting production， and based on the macroscopic defect characteristics observed on-site， the microstructure of the crack zones， and the distribution of eutectic carbides， the relationship between cracks in continuous casting billets and carbide enrichment was analyzed. Optimal process parameters were determined as follows： mold flux basicity of 0.85， viscosity of 0.05 Pa·s at 1 300 ℃， and melting point of 990 ℃； water flow rate of the mold wide face at 115 m³/h， water flow rate of the narrow face at 20 m³/h， and a cooling water temperature difference of 2.2-2.4 ℃. Based on these findings， the mold flux and mold cooling regimes were optimized. Existing industrial validation results indicate that， following optimization， the non-destructive testing pass rate for continuous casting products reached 95%-97%， with the center porosity grade controlled at 1.0-2.0 and the eutectic carbide grade at 2.0-3.5. Overall quality has approached the level of mold-cast products of the same specification. These research findings provide a reference for crack control and carbide regulation in the continuous casting of high-carbon， high-chromium die steels.关键词：Cr12MoV Die Stee;Continuous Casting;Segregation;Carbide;Surface Cracks3|0|0更新时间：2026-10-13
- 摘要：To address the issue of excessive DS-type inclusions in 1.2343 hot-work die steel produced by electroslag remelting （ESR）， a process approach involving slag system optimization was proposed. Two new slag systems （E40F and E50F） were evaluated in industrial trials. Using FactSage software and empirical formulas， key physical properties of the slag systems—such as basicity， viscosity， conductivity， and activity of certain components—were calculated， forming the basis for the ESR process. Industrial trials revealed that the E50F slag system exhibited the best overall performance， with moderate SiO₂ content enabling the modification of hard Al₂O₃ inclusions into low-risk spherical inclusions. It also combined moderate fluidity with Al₂O₃ inclusion suppression capability， making it the preferred choice for inclusion control in the finished product in production. The E40F slag system exhibited strong modification capability but suffered from high viscosity， leading to difficulties in inclusion flotation and higher residual inclusion levels， resulting in inferior performance compared to E50F. The 37 slag system exhibited the highest Al₂O₃ activity， causing significant secondary hard inclusion precipitation without modification capability， yielding the poorest inclusion control performance. Using the optimized E50F pre-melted slag significantly decreased the DS inclusions in 1.2343 hot-work die steel， achieving a rating level of 0.5 with all inclusions smaller than 15 μm. The total inclusion count decreased by 27% compared to the original slag system. The E50F slag system is more effective in removing inclusions from 1.2343 hot-work die steel.关键词：1.2343;Hot-work Die Steel;Electroslag Remelting;Slag System;Inclusions;Basicity1|0|0更新时间：2026-10-13
- 摘要：To investigate the solidification structure and inclusion behavior during the vacuum arc remelting process of ultra-large die-casting die steel， and to explore and study the process parameters of vacuum arc remelting， computer numerical simulation technology was employed to investigate the evolution of the molten pool shape during the smelting process of ultra-large die-casting die steel ingots （diameter 1 250 mm） under three different melting rates. The segregation patterns of elements were analyzed， and the relationship between melting rate and inclusion removal trajectory， as well as the effect of different helium pressures on the solidification quality of the ingots， were studied. The results showed that， during steady-state melting， the growth rate of molten pool depth was directly proportional to the melting rate. When remelting at melting rates of 12.50 kg/min， 13.65 kg/min， and 15.00 kg/min， the simulated increasing rates of molten pool depth were 0.257 mm/min， 0.307 mm/min， and 0.397 mm/min， respectively. The inclusion removal trajectories were reasonable at all three melting rates. When the melting rate was set at 12.50 kg/min and 13.65 kg/min， the solidification front of the molten pool could not reach or fully reach the edge of the crystallizer， posing a higher risk of subsurface inclusions on the lower surface of the ingot. The water cooling effect at the bottom of the crystallizer was extremely strong during the initial stage of remelting， resulting in a high cooling rate. Simulation calculations showed that C， V， Cr， and Mo all exhibited negative segregation to varying degrees at the three melting rates， with C and V being the most pronounced， followed by Mo， and Cr showing relatively less segregation. When the ingot height reached 500 mm， the negative segregation of Cr and Mo was essentially eliminated， and the negative segregation trend of C and V significantly weakened. Computational simulations studied the effect of helium cooling on the depth of the two-phase region at two melting rates. The introduction of helium significantly reduced the depth of the two-phase region， reducing the depth by over 40%. Within a certain range， the pressure of the introduced helium was inversely proportional to the depth of the molten pool's two-phase region. The introduction of helium significantly reduced the segregation effects of various alloying elements in the top region of the ingot， with the shape of the severely segregated elements zone changing from conical to flatter. The concentration distribution of elements became more uniform. Elements in the core of the ingot tended to show positive segregation， while elements on the surface of the ingot tended to show negative segregation.关键词：Vacuum Arc Remelting;Ultra-large Ingot Die Casting;Die Steel;Inclusions;Helium Cooling0|0|0更新时间：2026-10-13
- 摘要：Aiming at the drawbacks of low production efficiency， high metal loss and severe carbide segregation existing in the conventional ingot casting process of cobalt-containing M35 high-speed steel， Jiangsu Shenyuan Group carried out research on the continuous casting process for 150 mm × 150 mm square billets by adopting a curved continuous caster equipped with electromagnetic stirring. M35 steel has a total alloy element content of approximately 22% and a wide solidification temperature range， which brings great difficulties to continuous casting， such as cracks， breakout and coarse eutectic carbides. A complete and stable production scheme was established through precise composition control within narrow ranges， development of special mold flux with low melting point and low viscosity， matching submerged nozzle insertion depth of 90 mm–95 mm， molten steel superheat of 40 ℃–50 ℃ and stable casting speed of 1.00 m/min–1.20 m/min， as well as the optimization of mold oscillation， dual electromagnetic stirring at mold and strand end， soft secondary cooling system and high-temperature straightening process at 950 ℃–1 000 ℃. More than 200 tons of continuous casting billets were produced in industrial trials， and both internal and surface quality of the billets met the requirements of downstream processing. Compared with ingot casting， the eutectic carbide segregation grade of hot-rolled wire rods is reduced from Grade 3.0 to Grade 1.5， the carbide size is significantly refined， the phase microstructure is improved， the finished product exhibits favorable ductility， and inclusion levels meet the standard requirements. This process can completely replace ingot casting， raise the yield by 7%–10% and greatly reduce production costs， which provides a practical engineering reference for continuous and stable mass production of high-alloy cobalt-bearing high-speed steel.关键词：High-speed Tool Steel;M35;Continuous Casting Billet;Process Exploration;Yield0|0|0更新时间：2026-10-13
Smelting and Solidification
- 摘要：Taking V4 high-speed steel as the research subject， we employed three different processes—electroslag remelting， powder metallurgy， and spray forming. The effects of process differences on the microstructure and properties of large-sized modules were systematically compared， and the comparative advantages of the spray forming process were comprehensively analyzed. Experimental results showed that electroslag-remelted V4 steel exhibited severe carbide segregation， presenting a network-like and banded distribution with a carbide inhomogeneity reaching grade 8 and large carbide particle sizes of approximately 11.1 μm to 11.7 μm； powder-metallurgy V4 steel exhibited the most uniform microstructure， with a carbide inhomogeneity of grade 0 and a carbide size of only 3.0 μm； spray-formed V4 steel exhibited a carbide inhomogeneity of grade 1 and a carbide size of 9.0 μm， with significantly better microstructure uniformity than electroslag-remelted steel. After similar heat treatment processes， all three steels achieved hardness above 62 HRC. Among them， spray-formed V4 steel exhibited a hardness of 62.8 HRC， slightly lower than that of powder-metallurgy V4 steel （63.8 HRC） and electroslag-remelted V4 steel （63.6 HRC）， but it exhibited the best wear resistance with a wear loss of only 0.036 g. In summary， spray-formed V4 steel demonstrated microstructure uniformity and wear resistance comparable to powder-metallurgy V4 steel， while also offering relatively greater cost advantages. These findings provide theoretical and experimental references for the selection of preparation processes for V4 series high-performance high-speed steel.关键词：Electroslag Remelting;Powder Metallurgy;Spray Forming;V4-Series High-Speed Steel;Carbides;Wear Resistance0|0|0更新时间：2026-10-13
- 摘要：Taking as-cast H13 hot-work die steel as the research material， specimens were austenitized at 1 100 ℃ for 20 min followed by oil quenching， and subsequently subjected to tempering treatments at 560 ℃， 620 ℃ and 650 ℃ with varying tempering durations and cycles. Optical microscopy （OM）， scanning electron microscopy （SEM）， electron probe microanalysis （EPMA）， X-ray diffraction （XRD）， electron backscatter diffraction （EBSD）， hardness measurements and Charpy impact tests were employed to investigate the effects of tempering parameters on microstructure evolution and mechanical properties of the steel. The results reveal that tempering temperature dominates the microstructure evolution of H13 steel. With increasing tempering temperature， time and number of cycles， the lath feature of martensite gradually weakens； precipitated fine dispersed carbides undergo aggregation， spheroidization and coarsening， while the retained austenite content and dissolved carbon content in martensite show an overall decrease， and the microstructure evolves from tempered martensite to high-temperature tempered microstructure. Tempering at 560 ℃ retains relatively high hardness， among which the group tempered at 560 ℃ for 65 min with three cycles achieves the maximum hardness of 54.6 HRC， yet a low impact absorbed energy. Tempering at 650 ℃ accelerates matrix recovery and carbide spheroidization， and the group tempered at 650 ℃ for 65 min with two cycles achieves the highest impact absorbed energy of 15.39 J with superior impact toughness. The fracture morphology gradually transforms from cleavage/quasi-cleavage fracture at low tempering temperature to dimple ductile fracture at high tempering temperature. Optimized regulation of tempering temperature， time and number of cycles enables synergistic improvement in hardness and toughness of H13 steel.关键词：H13 Steel;Hot-work Die Steel;Tempering Process;Microstructure Evolution;Retained Austenite;Mechanical Properties2|0|0更新时间：2026-10-13
- 摘要：Hot compression experiments were conducted on a large-scale 4Cr5Mo2V die-casting die steel using a Gleeble 3800 thermal simulation testing machine. The deformation parameters were set as follows： deformation temperatures ranging from 1 000 ℃ to 1 200 ℃， the strain rates were 0.01 s⁻¹， 0.1 s⁻¹， 1 s⁻¹， 10 s⁻¹ respectively， and a reduction of 50%. The results show that both temperature and strain rate have significant effects on the flow stress； specifically， the flow stress decreases with increasing temperature and increases with increasing strain rate. A high-temperature flow constitutive model for the large-scale 4Cr5Mo2V die-casting die steel was derived based on the hyperbolic-sine modified Arrhenius equation， and the thermal deformation activation energy was determined to be 387.273 kJ/mol. A strain-compensated constitutive equation was further developed to enhance the model accuracy. The linear correlation coefficient （R²） between the predicted and experimental values was found to be 0.976， confirming that the strain-compensated constitutive equation possesses high precision and reliability. Based on the established processing maps， the optimal hot-working window was identified as 1 030 ℃–1 200 ℃ with strain rates below 0.060 s⁻¹. Microstructural analysis revealed that at low temperatures and high strain rates， the microstructure exhibits chain-like， incompletely recrystallized features. Dynamic recrystallization is a thermally activated process； increasing the deformation temperature promotes uniform equiaxed grains， but excessively high temperatures lead to grain coarsening. These findings provide a theoretical basis for optimizing the forging process of large 4Cr5Mo2V die-casting molds.关键词：Die-casting Die Steel;Hot Deformation;Dynamic Recrystallization;Hot Processing Map0|0|0更新时间：2026-10-13
- 摘要：The demand for super-large plastic mould steel blocks is growing day by day， to reveal the microstructure at different positions of a super-large 1.2738 plastic mould steel block with dimensions of 1 200 mm × 1 300 mm × 2 700 mm during quenching， the cooling rate ranges at various locations of the large block were non-destructively determined using the DEFORM software. On this basis， continuous cooling transformation tests were carried out using a dilatometer. Combined with the test results of metallography， hardness and retained austenite， the phase transformation characteristics of 1.2738 steel at an ultra-low cooling rate of 0.008 °C/s were analyzed. The results indicate that during the “water-air-water” quenching process of the super-large block， the cooling rate at the core is only 0.026 °C/s， which is far lower than that of conventional rolled medium-thick plates and small-to-medium blocks. Considering comprehensive material properties， the quenching cooling rate range of 0.02 °C/s to 0.03 °C/s is the lower limit for controlling the final microstructures of large blocks. When the cooling rate is above this range， the obtained microstructures are dominated by martensite and upper and lower bainite； when the cooling rate falls below this range， granular bainite is the primary phase.关键词：Plastic Mould Steel;Cooling Rate;Bainite;Hardness0|0|0更新时间：2026-10-13
- 摘要：This study systematically investigated the effect of isothermal spheroidizing annealing on the microstructure and properties of a novel hot-work die steel 5CrNiMoVNb. The as-forged microstructure primarily consists of lath bainite， martensite， and a small amount of carbides， exhibiting a hardness of 528 HV. The results demonstrated that the austenitizing temperature and isothermal temperature play a decisive role in determining the spheroidized microstructure and hardness. An ideal spheroidized pearlite structure with a high spheroidization rate and uniformly distributed carbides was achieved at an austenitizing temperature of 790 ℃ and an isothermal temperature of 690 ℃. Excessively high austenitizing temperature （810 ℃） led to carbide coarsening and a decreased spheroidization rate， while an excessively low isothermal temperature （630 ℃） inhibited the spheroidization process， resulting in the formation of lamellar pearlite. Surface hardness analysis confirmed that the increase in the spheroidization rate of the pearlite structure directly resulted in a significant reduction in material hardness. The optimal process window for isothermal spheroidizing annealing under the conditions of this study has been determined. The low-hardness， high-spheroidization-rate microstructure obtained under this process is expected to be beneficial for subsequent machining and final heat treatment.关键词：Hot-work Die Steel;5CrNiMoVNb;Isothermal Spheroidizing Annealing;Spheroidized Pearlite;Microstructure;Hardness75|37|0更新时间：2026-10-13
- 摘要：The evolution of primary carbides and the mechanism of microstructural stability in powder metallurgy AISI M3：2 steel during holding at different temperatures were systematically investigated. Scanning Electron Microscopy （SEM） was employed to characterize the microstructure and carbide precipitation characteristics of the material， and room temperature impact toughness tests were conducted to analyze the influence of microstructural evolution on mechanical properties. The research results indicate that during holding at temperatures of 1 100 ℃ and below， the M₆C-type （tungsten-rich） and MC-type （vanadium-rich） primary carbides in the steel exhibit good thermal stability. Their average size and volume fraction do not significantly change with increasing holding temperature and prolonging holding time. This phenomenon is primarily attributed to the initial microstructural homogeneity imparted to the material by the powder metallurgy preparation process， as well as the extremely high thermodynamic stability of the two carbides themselves. When the holding temperature is raised to 1 150 ℃ and the holding time is prolonged， the M₆C-type carbides with relatively low thermodynamic stability undergo substantial dissolution， leading to a sharp decrease in the overall volume fraction of carbides. Simultaneously， the undissolved residual M₆C-type carbides undergo significant coarsening and form discontinuous ring-like distribution characteristics at grain boundaries. The aforementioned microstructural evolution ultimately results in a significant reduction in the impact toughness of the material. Therefore， under prolonged holding conditions， 1 150 ℃ serves as the critical temperature for the microstructural stability of primary carbides in this type of high-alloy tool steel， providing crucial experimental data support for optimizing heat treatment process parameters and precisely controlling the hot working window.关键词：Powder Metallurgy Tool Steel;Carbide;Alloying Element;Austenitizing;Heat Treatment78|25|0更新时间：2026-10-13
- 摘要：In order to study the effect of high-temperature diffusion annealing on the microstructure of 6Cr5Mo2V1 alloy tool steel， thermodynamic phase diagram calculations were conducted， and high-temperature diffusion annealing experiments at different temperatures were performed to analyze the effects of high-temperature diffusion annealing on the microstructure and alloying elements of 6Cr5Mo2V1 alloy tool steel， while friction and wear performance tests were also carried out. The results show that after holding 6Cr5Mo2V alloy tool steel at 1 230 ℃ for 3 hours， Cr-rich carbides diffuse and dissolve into the matrix， significantly alleviating compositional segregation. However， primary carbides rich in V and Mo with sizes ranging from 10 to 50 μm are highly stable and difficult to dissolve during the homogenization process. When the diffusion annealing temperature reaches 1 250 ℃， the low-melting-point eutectic structure remelts， forming micropores after cooling. Friction and wear tests indicate that samples subjected to 1 230 ℃ diffusion annealing exhibit the highest tribological stability.关键词：6Cr5Mo2V1;Alloy Tool Steel;High-temperature Diffusion Annealing;Microstructural Evolution0|0|0更新时间：2026-10-13
- 摘要：To meet market demands for steel materials featuring high polishability， superior corrosion resistance and excellent strength-toughness balance， a high-quality corrosion-resistant plastic die steel with improved comprehensive properties is developed via optimizing chemical composition and heat treatment processes. The steel was smelted by the process route of "electric arc furnace + vacuum refining + electroslag remelting"， and large flat steel with a cross-sectional dimension of 230 mm×710 mm was manufactured using a 35MN rapid forging press. The effect of different post-forging heat treatment processes on the microstructure and properties of a novel corrosion-resistant plastic die steel 3Cr13NiMoVN was studied using JMatPro software， OM， SEM， hardness tester and impact testing machine. The results show that the post-forging process of 1 050 ℃ normalizing + isothermal annealing yields a more uniform spheroidal pearlite microstructure. The microstructure obtained by 1 000 ℃ normalizing + isothermal annealing is identical to that of the conventional annealing process， namely carbide-depleted zones exist in the microstructure， and chain-like carbides precipitate along twin boundaries， and these features are inherited by the tempered microstructure. The non-uniform annealed microstructure has a significant effect on the impact toughness of the steel. The impact toughness of the steel treated by 1 050 ℃ normalizing + isothermal annealing + quenching and tempering is 77%–80% higher than that of the steel treated by 1 000 ℃ normalizing + isothermal annealing + quenching and tempering process.关键词：Plastic Die Steel;Heat Treatment Process;Microstructure;Properties0|0|0更新时间：2026-10-13
Forming and Phase Transition
- 摘要：To address the issues of coarse prior austenite grains， wide martensite laths， and carbide coarsening in conventionally quenched and tempered H13 hot-work die steel， the effects of a carbide pre-precipitation–assisted critical quenching process on microstructure evolution and thermal fatigue behavior were investigated. The results show that， after a treatment comprising quenching at 1 050 ℃， carbide pre-precipitation at 730 ℃， and critical quenching at 930 ℃， the prior austenite grain size was significantly refined from 126.9 μm （obtained after 1 050 ℃ quenching） to 36.3 μm， while the average martensite lath width decreased from 1.23 μm to 0.54 μm. The fine dispersed carbides formed in the pre-precipitation stage were not completely re-dissolved during subsequent critical austenitization， thereby exerting a strong pinning effect on grain boundary migration and facilitate nucleation， which resulted in a synergistic refinement of the microstructure. During long-term tempering at 610 ℃ and 700 ℃， both processes exhibited carbide dissolution and coarsening； however， the carbide pre-precipitation–assisted critical quenching sample showed smaller carbide size， more uniform distribution， and a significantly reduced coarsening rate. Both samples exhibited a two-stage softening behavior characterized by an initial rapid decrease followed by a gradual decline. Compared with conventional treatment， the carbide pre-precipitation–critical quenching sample demonstrated a lower softening rate under high-temperature long-term tempering， indicating markedly improved resistance to tempering softening. Thermal fatigue tests further revealed that after 1 000 thermal cycles， the treated samples exhibited fewer cracks and shorter average crack length， more tortuous crack propagation paths， and a significantly suppressed crack growth rate， demonstrating superior thermal fatigue resistance.关键词：Hot Work Die Steel;Thermal Stability;Thermal Fatigue;Carbide Pre-precipitation;H13 Steel0|0|0更新时间：2026-10-13
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