Microalloying ’25: International Symposium on Microalloying
Schedule
2–5 June 2025 • The Hythe Vail • Vail, Co, USA
Monday, 2 June 2025 | |
| 4 p.m. | Registration |
| 6 p.m. | Reception |
Tuesday, 3 June 2025 | |
| 7 a.m. | Breakfast |
| 8 a.m. | Opening Remarks Emmanuel De Moor, Colorado School of Mines |
| 8:10 a.m. | Molybdenum Market Update and Trends, Kevin Pritchet, Climax Molybdenum Co. |
| 8:40 a.m. | Advanced Long Products: Recent Development and Applications of Vanadium Microalloyed Steels Rolf Schmidt, Vantage Alloys AG In this lecture, the physical metallurgy of vanadium microalloying and its impact on properties of the respective steel groups is described. As one of the most important fields of application, the impact of V microalloying on rebars will be described. Besides mandatory application under Chinese specifications, some interesting and unconventional applications in Europe and the Americas will be highlighted. For high-strength applications in the automotive industry using forging steels, main applications of air hardening pearlitic and bainitic concepts are highlighted, showing remarkable improvement of performance and economic impact compared to conventional Q/T grades. The impact of V alloying on high-strength grades for heavy beam applications in construction is described, highlighting hot rolling practices as well as the economic and safety impact of this technology. Concerning high-carbon pearlitic grades, vanadium shows a great ability to refine pearlitic lamella structures, leading to ultrahigh-strength wire grades as well as to rails with improved rolling contact fatigue resistance for heavy load, tight radii or other critical applications. |
| 9:10 a.m. | Complementary Metallurgical Functionalities of Molybdenum in Microalloyed Steels Hardy Morhbacher, Niobelcon BV Molybdenum, similar to microalloying elements, presents a comparably large atom size in the iron lattice and a tendency of forming carbides when alloyed to steel. Yet, molybdenum carbide formation is unlikely to occur in austenite even for high alloy additions. Accordingly, molybdenum mainly acts by solute drag effects facilitating austenite pancaking complementary to microalloy effects. Under severe thermomechanical-controlled processing (TMCP) conditions, molybdenum counteracts dynamic recrystallization at low austenite temperature. Solute molybdenum delays the austenite-to-ferrite transformation, thereby also obstructing pearlite formation. Solute drag on the phase front can help optimize the conditions of interphase precipitation of microalloys. In transformed ferrite, molybdenum enhances the efficiency of spontaneous microalloy precipitation. Remaining substantially solute in ferrite, molybdenum helps control recovery and recrystallization processes during annealing treatments complementary to microalloys that precipitate in-situ. Finally, solute molybdenum can mitigate harmful effects of diffusible hydrogen. The contribution demonstrates the potential of complementary metallurgical functionalities based on recent steel developments. |
| 9:40 a.m. | Niobium Use in the Steel Industry for the Last 50 years and an Outlook on Future Applications Rafael Mesquita, CBMM; Jitendra Patel, International Metallurgy Ltd. |
| 10:10 a.m. | Break |
| 10:30 a.m. | Modeling Austenite Conditioning and Decomposition in Line Pipe Steels Matthias Militzer, The University of British Columbia Nb-Ti microalloyed line pipe steels are thermomechanically controlled processed to obtain the fine ferrite and/or bainitic microstructures required for the property demands of pipeline constructions. Here, austenite conditioning and decomposition are the microstructure phenomena of primary interest both during hot rolling as well as in the weld heat-affected zone (HAZ). Thus, the present work emphasizes the development of microstructure models based on systematic laboratory studies that combine in-situ laser ultrasonic measurements with ex-situ microstructure characterization and mechanical testing. Austenite grain growth and recrystallization are primarily affected by pinning of Ti-rich carbonitride and NbC precipitates, whereas austenite decomposition depends on cooling rate and the amount of Nb in solution. The high-angle grain boundary density in the final microstructure is a critical parameter for strength and fracture toughness. Based on these investigations, structure-property models have been developed applicable to hot rolling and HAZ thermal paths for selected line pipe steels. |
| 10:50 a.m. | Recent Developments of Vanadium Microalloyed Strip and Plate David Crowther, Vanitec Vanadium microalloying can be applied to a wide range of strip and plate products, and the relatively high solubility of vanadium carbides and nitrides confer numerous benefits. This paper will briefly summarize some of the more recent developments in vanadium-containing strip and plate, emphasizing how vanadium precipitates generate microstructures with advantageous properties. In advanced high-strength steels for automotive applications such as transformation-induced plasticity (TRIP) steels and dual-phase steels, vanadium additions result in a microstructural refinement and an increase in strength. In dual-phase steels, differential precipitation of vanadium between ferrite and martensite results in improvements to ductility and hole expansion. In high-strength line pipe such as X80, the combination of vanadium and niobium microalloying results in improved toughness and weldability. The reduced mill loads associated with vanadium microalloying allow the production of high-strength hot-rolled strip with increased width and improved shape, and enlarge processing windows for recovery annealed strip. High-strength, thick normalized plates with yield strengths up to 460 MPa can be produced using vanadium additions, the vanadium precipitates giving both grain refinement and precipitation strengthening. |
| 11:10 a.m. | Plate Hot Rolling of Microalloyed Steels: From Metallurgical Mechanisms to Microstructural Modeling Pello Uranga, CEIT-BRTA and University of Navarra Plate hot rolling of microalloyed steels involves a complex interplay of thermomechanical processing and microstructural evolution. This work investigates metallurgical mechanisms, such as recrystallization, grain refinement, and precipitation during deformation and cooling, with a focus on Nb, Mo and Ti microalloying additions. These elements influence dynamic and static recrystallization kinetics, retard grain growth, and enhance precipitation strengthening through nanoscale carbide formation. The study employs MicroSim software to model microstructural evolution applied to plate rolling, predicting austenite grain size distribution evolution and phase transformations under various processing conditions. By integrating advanced metallurgical models with industrial rolling schedules, the software provides insights into microstructural homogeneity through-thickness caused by temperature and strain gradients. This work bridges fundamental metallurgical understanding with the latest advances and functionalities of this modeling tool, enabling the development of high-performance steels while supporting energy-efficient and sustainable production practices. |
| 11:30 a.m. | Lunch |
| 1 p.m. | Microstructure Optimization for Improving Low-Temperature Toughness of Microalloyed X65 and X70 Line Pipe Steel Plates via Thermomechanical-Controlled Processing Jing Su, SSAB Americas High-strength low-alloy (HSLA) steels are widely used in the production of modern line pipe steels through thermomechanical controlled processing (TMCP). Line pipe steels are required to exhibit high strength and excellent low-temperature toughness. In this study, a low-carbon Ti-Nb-Mo microalloyed steel composition was used to produce 0.5-inch gauge API X65 and X70 line pipe discrete plates using TMCP, incorporating the MULPIC cooling system. Various rolling practices were employed, including different reduction distributions, lowering finish rolling temperature and varying stop cooling temperature. Comprehensive microstructure and texture characterization was conducted using optical microscopy and scanning electron microscopy (SEM) techniques with electron backscatter diffraction (EBSD). The influence of microstructure and texture on tensile properties, Charpy impact toughness and drop weight tear testing (DWTT) performance was investigated. The optimized microstructure, comprising a combination of bainitic ferrite and polygonal ferrite, enabled the successful production trial of 0.5-inch API X65 and X70 plates with superior DWTT performance. |
| 1:20 p.m. | Processing and Alloy Design Strategies for Producing API X70 Heavy Gauge Wide Plate With Stable Low-Temperature DWTT Average/Standard Deviation Performance João Souto, CBMM Today’s market for API pipeline steels requires higher strength and fracture toughness performance in heavier gauges/larger pipe diameters including achieving low-temperature stable drop weight tear test (DWTT) performance. The key metallurgical challenge lies in attaining a fine homogenous through-thickness microstructural attributes essential for achieving the desired DWTT performance. Several trials were designed for JSW Anjar to produce heavy-gauge wide API X70 plate. The alloy/processing strategies were simulated through the plate mill hot rolling level 2 model to check suitability for the equipment capability and metallurgical analysis by mean flow stress. In addition, the metallurgical model MicroSim Plate Mill was used to model the through-thickness austenite grain size evolution attributes that have been shown to achieve the desired DWTT performance. The effect of an optimum Nb content along with optimized processing is reflected in the final plate mechanical properties, especially the low-temperature DWTT average/standard deviation performance. |
| 1:40 p.m. | Use of Niobium for Structural Heavy-Gauge Plates Produced by Normalizing Rolling Daniel Bojikian Matsubara, Gerdau Normalizing rolling is a thermomechanical-controlled process that emulates the normalization heat treatment directly after the final rolling pass. It is an economically advantageous production route; however, the final microstructure does not bear the same characteristics as the off-line heat-treated material, especially for plate gauges above 50 mm. This work shows an innovative steel design for plates up to 76.20 mm in thickness, by adding larger amounts of Nb and lower quantities of C and Mn. This chemical composition was elaborated aiming the improvement of centerline segregation, microstructural homogeneity of the plate and proper Charpy impact toughness throughout the thickness of the rolled unit. For this assessment, a laboratory ingot was produced for precipitate characterization and industrial slabs were rolled for evaluation of mechanical properties, microstructural features and welded joint characterization. Findings showed a much more homogeneous material in terms of microstructure and mechanical properties when compared to conventional structural steel for the same application. |
| 2 p.m. | Effect of Nickel Alloying on Strength and Toughness Properties in Heavy Plate Steels Hardy Morhbacher, Niobelcon BV Heavy plates used for offshore applications are often confronted with harsh environments demanding superior toughness properties especially in mid-plate thickness and weld heat-affected zone (HAZ). Typically, such high-strength low-alloy steels are niobium microalloyed produced by thermomechanical-controlled processes or normalizing processes to minimum yield strength ranging from 350 to 460 MPa. Experience shows that the required properties can only be achieved by nickel alloying in the range of up to 1.0%. This study investigates the reduction of carbon and increase of nickel content on strength and toughness in base metal and weld HAZ for 30-80 mm plate gauge. The results indicate that superior performance can be achieved with increasing content of nickel, which may influence the stability of niobium precipitates. Crack tip opening displacement tests performed in the coarse-grain heat affected zone at –20°C show remarkable improvement. The current contribution aims to explain the observed effects based on microstructural analysis and builds a framework allowing optimized alloy design. |
| 2:20 p.m. | Break |
| 2:40 p.m. | Effect of Ultralow Nb Microalloying on the Microstructure – Property Relationship of Low-C, Low-Mn Structural Steel Plates Tanya Ros, Cleveland-Cliffs Inc. Structural steel plates are widely used in construction and infrastructure. Ultralow niobium additions can enhance strength, enabling reductions in carbon and manganese content in traditional alloys. This study investigates the microstructure-property relationship of two low-carbon/low-manganese alloys microalloyed with 0.006–0.009% Nb, compared to a traditional structural alloy. Three rolling and cooling conditions produced plates from the same alloy meeting tensile property requirements for ASTM A36, S255 and S355 standards. Results show that NbC nanoclusters compensate for the loss of strength typically associated with the reduction of carbon (to less than 0.1%) and manganese (1.1% to 0.65%) via solid solution strengthening. Transmission electron microscopy analysis revealed the effect of ultralow niobium additions and the processing conditions on precipitate size and volume fraction. The alloy met mechanical properties requirements for the targeted grades under the specifics processing conditions. |
| 3 p.m. | Isolating Acicular Ferrite Effects on Impact Toughness in V-Microalloyed Steel Heat-Affected Zone Simulations Adam Church, Colorado School of Mines Previous work has shown that promoting acicular ferrite (AF) in the heat-affected zone improves low-temperature impact toughness over grain boundary ferrite (GBF). In this work, the synergistic effects of peak temperature, N content, ferrite microconstituent type and amount, and effective grain size are investigated to elucidate the role of AF on impact toughness. High-strength, low alloys were microalloyed with V and produced in experimental heats with two N levels. Heating both alloys to austenitization temperatures above and below the microalloy precipitate dissolution temperature produced conditions with comparable hardness. The lower austenitization temperature specimens were polygonal ferrite/AF mixtures while the higher temperature specimens were AF/GBF mixtures. Higher N content yielded finer prior austenite grains and therefore more primary ferrite at both austenitization temperatures. The higher austenitization temperature conditions had more AF, producing a finer effective ferrite grain size. Overall, higher peak temperature and lower N content improved impact toughness by promoting AF. |
| 3:20 p.m. | Effect of Vanadium and Niobium Microalloying on the Heat-Affected Zone of High-Thickness Welded Joints Andrea Di Schino, University of Perugia The present study aims to investigate the effect of vanadium addition on microstructure in the hat-affected zone (HAZ). Multi-pass welded joints were manufactured on 15 mm thick S355 steels with different V content, using robotic GMAW process. A steel variant micro-alloyed with both V and Niobium has also been considered. Results are compared to a standard S355 steel based on C-Mn composition without microalloying elements. Moving through the different subregions of the welded joints, the results show a heterogeneous microstructure, characterized by the presence of ferrite with different morphologies, bainite and martensite/austenite (M/A) islands. The presence of V appears to reduce the carbon solubility during phase transformations due to the continuous heating of the welding process. The consequence is, in addition to the formation of very fine and dispersed precipitates, the presence of a lower percentage of brittle M/A phase in the high-V-content variant compared to the vanadium-free material. Despite the presence of brittle phase, the microalloyed variants show a mechanical strengthening without loss of neither ductility nor fatigue resistance. The combined presence of both hard and soft microstructural constituents in HAZ allows a stress-damping behavior, which promises improved resistance to crack propagation. |
| 3:40 p.m. | Break |
| 4 p.m. | Suppressing Hydrogen-Induced Intergranular Fracture by Carbon Segregation at Prior Austenite Grain Boundary in High-Strength Martensitic Steels Kazuho Okada, National Institute for Materials Science This study demonstrated that the resistance against hydrogen embrittlement was improved by increasing the concentration of carbon segregated at the prior austenite grain boundary (PAGB) in low-carbon as-quenched martensitic steels (Fe-3Mn-0.2C (wt.%)). The specimens with/without carbon segregation treatment (Non-seg and Seg, respectively) had almost the same microstructure, other than higher carbon concentration at PAGB in the Seg. While the Non-seg and Seg without hydrogen exhibited similar mechanical properties (tensile strength: ~1.5 GPa, total elongation: ~9%), the maximum tensile stress and fracture toughness of the hydrogen-charged specimen were much higher in the Seg than those in the Non-seg at identical diffusible hydrogen contents. Additionally, the fraction of intergranular fracture surface was much smaller in the Seg. It is concluded that the segregated carbon suppressed the accumulation of hydrogen around PAGB by site competition and increased the cohesive energy of PAGB, leading to significantly improved resistance against hydrogen-induced intergranular fracture. |
| 4:20 p.m. | Mixed Microalloying Strategies for Microstructure and Property Control in Compact Strip Production Matt Enloe, Steel Dynamics Inc. – Flat Roll Group Southwest-Sinton Division Thermomechanical processing of microalloyed flat-rolled steels manufactured by the compact strip process is limited by numerous physical constraints. Alloy and process designs must account for substantial variations in casting practice, low equalizing furnace temperatures relative to traditional integrated mill methodologies, and generally high baseline nitrogen levels. Accordingly, molybdenum may be employed independent of solubility constraints as a strategic alloy addition to reduce variations in microstructure and resultant product properties. This contribution details the use of molybdenum in the manufacture of selected high-strength low-alloy steels with specific focus on molybdenum effects on austenite recrystallization kinetics during hot rolling. Molybdenum is shown as a solute to improve product performance consistency, in part due to its mechanistic independence from both nitrogen variation and solubility considerations. Additional beneficial effects of molybdenum on microalloy carbide precipitation and austenite decomposition are presented within the frame of the compact strip process. |
| 4:40 p.m. | Optimization of Hot-Rolled Structured Steels Based on Nb Microalloying to Reduce Costs and GWP Paul Lalley, CBMM Europe All demanding modern applications such as structural, energy and automotive require steels with an increasingly high level of strength and ductility whilst retaining good cost competitiveness as well as fulfilling ever-demanding emission levels. Structural steels have traditionally focused on obtaining strength via C and Mn with some mini-mill producers utilizing V microalloying to achieve properties. But, more stringent sustainability credentials and pressure to reduce costs as well as improved productivity are factors that are motivating producers to utilize low- to medium-C chemistries with reduced Mn and V where the benefits to product quality, processability and especially costs are paramount. |
Wednesday, 4 June 2025 | |
| 7 a.m. | Breakfast |
| 8 a.m. | Influence of Microalloying Additions on Hardenability and Phase Transformation Behavior of Ultrahigh-Strength Steels Processed via Direct Quenching and Other Novel Processing Routes Mahesh Somani, University of Oulu The effect of steel composition on the phase transformation characteristics and hardenability of boron steels was studied under direct quenched conditions. It was established that microalloying with Nb leads to increased hardness and hardenability, particularly in strained matrix. Both Cr and Mo were less effective in increasing hardenability than formulated in ASTM standard. During the development of direct quenching and partitioning (DQ&P) process for realizing tough, ductile, ultrahigh-strength steels using 0.2–0.4C (high) Si and/or Al steels, microalloying with Nb retarded austenite decomposition during partitioning, whereas a small addition of Mo could not hinder decomposition of austenite in presence of martensite formed during quenching step. In yet another study on the development of medium-carbon nanostructured bainitic steels, alloying with Mo+Nb refined the prior austenite grain size leading to faster onset of bainite transformation, but their hindering influence on the growth of bainitic sheaves led to extensive refinement of the transformed bainite. |
| 8:20 a.m. | Effect of the Hot Rolling Conditions on Microstructure and Mechanical Properties of Multiphase Microalloyed Hot-Rolled Steels Cécile Rampelberg, CanmetMATERIALS and McMaster University Advanced high-strength steels (AHSS) have been developed to meet the automotive industry's demands for lightweight materials, improved vehicle safety, fuel efficiency and reduced CO2 emissions. AHSS requires a combination of high strength and high ductility, two properties that tend to be antithetical in steels. In response, researchers have developed alloys with complex, multiphase microstructures that employ, to varying degrees, dislocation and precipitation strengthening. This study focuses on high-strength, enhanced-ductility hot-rolled steels microalloyed with Nb, V, Mo and Ti. Pilot-scale investigations have revealed a significant correlation between hot rolling process parameters and the resulting mechanical properties of these steels. Carefully controlled industrial trials were performed and compared with the pilot-scale data. This approach facilitates the rapid optimization of both the alloy chemistry and the key hot rolling parameters required for improved strength and formability. In the longer term, this fundamental study aims to correlate the microstructural and the metallurgical process-property relationships. |
| 8:40 a.m. | Development of Hot-Rolled UHSS in an Unconventional Compact Strip Plant Felix Perez Meza, Steel Dynamics Inc. – Flat Roll Group Southwest-Sinton Division Both general lightweighting and desired performance improvements in the truck, trailer and heavy equipment industries necessitate increased usage of hot-rolled ultrahigh-strength of 700 MPa yield strength and above. To achieve yield strengths of 700 MPa or greater in hot-rolled high-strength low-alloy steels, a strategy utilizing multiple microalloying elements must be employed. This contribution outlines the industrial results of the design and development of HR 760LA (760 MPa min yield) containing Nb, V, Ti and Mo. A novel production process combines the positive effects of high-speed casting of intermediate-thickness slabs (110–130 mm) with discrete roughing and finishing stages. This process permits the efficient use of both Nb microalloying for recrystallization control and Ti and V microalloying for precipitation strengthening. Product development resulted in an adequate balance of microstructural refinement, precipitation strengthening and homogenization of the ferritic-bainitic microstructure to achieve requisite product strength, ductility and toughness. |
| 9 a.m. | Torsion as a Cold Rolling Simulant for Investigating Recrystallization Behavior Aidan Ravnik, Colorado School of Mines Hot torsion is commonly applied as a technique to simulate hot rolling behavior on the lab scale. It has been shown that microstructures produced via hot torsion may be directly compared to those resulting from traditional hot strip mill processes. Similarly, it is proposed that torsion may be used at room temperature for lab-scale simulation of cold rolling processes. The continuous distribution of strain through a torsion specimen may present a potent opportunity to investigate the influences of variation in recrystallization driving force and microstructural development within a single sample. This paper presents an experimental study comparing recrystallization behavior and microstructural development between low-carbon steel processed by torsion versus cold rolling followed by subsequent continuous annealing simulation. |
| 9:20 a.m. | Exploring the Role of Cr and Cr+Nb Microalloying in Phase Stability and Precipitation in Advanced High-Strength Steels: A CALPHAD Approach Paul Mason, Thermo-Calc Software Inc This talk explores the impact of Cr and Cr+Nb microalloying on phase transformations, retained austenite, martensitic transformation and precipitation behavior in advanced high-strength steels, using Thermo-Calc and the add-on module for precipitation kinetics, TC-PRISMA. CALPHAD simulations predict phase stability and precipitation kinetics, focusing on the formation of Cr-rich and Nb-containing carbides. The results are benchmarked against data from a published study on Fe-0.2C-1.5Mn-(Cr/Nb/V/Mo) steels to validate the modeling approach. Simulations demonstrate how Cr and Cr+Nb influence retained austenite stability and alter martensitic transformation pathways, with implications for mechanical properties. Precipitation kinetics simulations reveal VC precipitation behavior and volume fraction under different isothermal treatments, matching previously published experimental data. These findings highlight the benefits of computational thermodynamics for understanding and optimizing microalloying effects, aiding in the design of steels with tailored properties for automotive and structural applications. |
| 9:40 a.m. | Break |
| 10 a.m. | On the Stability of Microalloy Carbide Particles in the Intercritical Temperature Range Caio Pisano, CBMM Microalloying elements are strong carbide formers showing decreasing solubility as the austenite temperature is reduced as well as upon transformation to ferrite. Once precipitated, it is thought that only reheating to a higher austenite temperature can re-dissolve such carbides. Recent considerations and experimental evidence, however, indicated that carbide dissolution can occur already reheating into the temperature range of coexisting ferrite and austenite, especially when exceeding the Curie temperature. Such conditions prevail in various annealing, heat treatment, and welding cycles and have considerable implications on microstructure and properties. The contribution provides the fundamental background of this effect in terms of a detailed consideration of solubility and diffusivity of microalloys in the intercritical temperature range including an estimation of particle dissolution kinetics. Accounting for these mechanisms, scenarios applicable to real processes will be discussed highlighting the expected consequences. Subsequently, several examples will be shown demonstrating the perceived impact on microstructure and properties. |
| 10:20 a.m. | Synergic Effect of Nb, B, Ti, and Al on Zn Penetration and Liquid Metal Embrittlement During Spot Welding of AHSS Olga Girina, ArcelorMittal This work evaluates the effect of Nb microalloying alone and in presence of BTi and Al additions on sensitivity to liquid metal embrittlement (LME) of quenched and partitioned steels and to determine the major factors influencing LME cracking. The main results of the present study can be summarized as follows: (1) The effect of Nb on LME susceptibility in resistance spot welding (RSW) tests is insignificant and depends on welding cycles/conditions. (2) Additions of BTi to Nb microalloyed steel slightly reduce LME susceptibility in RSW tests. (3) Mechanisms of LME crack initiation in high-temperature tensile tests and RSW tests differ because of the differences in (a) stress-strain states; (( c) heating rates; (d) thermal gradients; (e) conditions of coating/substrate interface. (4) Gleeble high-temperature tensile cannot reproduce mechanical and thermal conditions of RSW and therefore cannot be used for accurate assessment of susceptibility to LME. However, these tests can help revealing the nature of LME. (5) Formation of surface Fe-Zn intermediate layer due to Zn diffusion into Fe weakens the development of LME cracks. (6) Segregation of Si in cracks during welding promotes propagation of LME cracks. |
| 10:40 a.m. | Titanium-Carbide Strengthened High-Strength Steels for Purpose-Built Vehicles Changgeun Lee, Hyundai Steel Co. Purpose-built vehicles (PBVs) are a new trend in the automotive industry. The change to a minimalistic design and material requirements changes as PBVs come with unique structural challenges. One steel class that can fulfill these requirements is ultrahigh-strength low-alloy (UHSLA) steel. UHSLA steels are characterized by high yield strength and bendability, while still being cost-efficient. Additionally, due to the low carbon content, weldability is higher in comparison to other high-strength steel grades. The properties are tailored by different microalloying concepts, with the aim of forming homogeneously distributed nanometer-sized carbides. The present study investigated the effect of varying titanium concentrations (0.1, 0.15 and 0.2 wt.%) as well as different processing parameters on the size and morphology distribution of titanium carbides. Observations by transmission electron microscopy are combined with kinetic modeling of the precipitation during heat treatment to predict the optimal heat treatment parameters. |
| 11 a.m. | Study of Microstructure, Hardness and Phase Transformation Behavior of Vanadium Microalloyed Steels Anastasiya Tselikova, Vantage Alloys AG Therefore, the present study aims to investigate the effect of vanadium microalloying in simplified ternary and quaternary alloying systems to modify the elastic modulus. High-purity lab melts were cast, processed and analyzed to separate the effect of vanadium from common alloying elements and impurities. Particularly, the influence of vanadium on transformation temperatures and macroscopic hardness were evaluated, with the goal to maximize interphase precipitates. It is observed that the increase in carbon and vanadium contents shifts, at higher cooling rates, the ferritic phase toward higher temperatures, while the addition of molybdenum delays the ferritic phase transformation. The increase of hardness is observed in steels with higher carbon and vanadium contents, at medium cooling rates, partly due to in-situ precipitation during continuous cooling. |
| 11:20 a.m. | Leveraging Artificial Intelligence to Decode the Microstructural DNA of Microalloyed HSLA Steels Simon Vander Vennet, OCAS For cold-rolled and annealed high-strength low-alloy grades, translating the established theoretical knowledge into an industrially robust processes remains a considerable challenge for novel grades with optimized properties. To address the complex interaction between Process-microStructure-Properties (P-S-P), an extensive experimental study was conducted in combination with machine learning and artificial intelligence techniques to deeper unravel the P-S-P correlations. Using state-of-the-art image analysis algorithms, classical features (with physical meaning) and neural network (latent) features were extracted from microstructural images, which enabled correlation between microstructure and the related processing or properties, respectively. In this work, the interplay between the different features is explored to evaluate their relevancy and capability to describe the microstructural evolution correctly. Subsequently, it is assessed to what extent these features are linked to the process history or final properties. The specific case of Nb is used to highlight the role of chemical composition in this P-S-P exploration. |
| 11:40 p.m. | Lunch |
| 1 p.m. | The Design of Nb, V and Mo Microalloyed Gear Steels for Grain Size Control During Carburizing Lucas Carrillo, Colorado School of Mines The development of microalloyed gear steels that resist austenite grain growth during carburizing is crucial to meet the demands of electric vehicle drivetrains. In this study, additions of Nb, V and Mo to 20MnCr5 were designed using Thermo-Calc® equilibrium simulations to prevent precipitation above the reheating temperature of 1,200°C, while maximizing the amount of precipitation during thermomechanical processing at 850°C and subsequent carburizing at 950°C. Three alloys — 20MnCr5+0.04% Nb, 20MnCr5+0.04% Nb+0.30% V and 20MnCr5+0.04% Nb+0.30% V+0.30% Mo — were designed and experimentally produced to address these goals. After pseudo-carburizing at 950°C, the addition of V+Nb improved grain refinement over Nb alone, and the finest grain size was observed with Nb, V, and Mo. The results of this work demonstrate the potential of multicomponent microalloying to generate fine austenite grain sizes during carburizing, which can provide the performance needed for the next generation of automotive drivetrains. |
| 1:20 p.m. | Abnormal Grain Growth Control in Gear Steels Noel Saxton, Nucor Corp. This study investigates the influence of different grain refining elements and processing conditions such as forging and normalization on the finished grain size in automotive gear steels. The research focuses on evaluating the effectiveness of aluminum versus niobium in controlling final part grain size, with particular emphasis on different processing conditions prior to carburization. The findings reveal key differences in grain size and distribution, providing insights into the role of microalloying elements in optimizing the performance of these steel grades. This comparison not only sheds light on the practical advantages of various grain refining elements but also offers valuable data for the effect of preprocessing conditions in the final part grain size. |
| 1:40 p.m. | Effect of Mn and Nb Additions on the Hardenability of Microalloyed Long Structural Steels Nicolas Tenaglia, Colorado School of Mines Continuous cooling transformation diagrams with and without austenite hot deformation were developed for three 0.14C microalloyed steels containing 0.8Mn-0.008Nb, 1.2Mn-0.008Nb and 0.8Mn-0.016Nb, in order to evaluate Mn and Nb effects on hardenability. For the nondeformed samples, it is found that both Mn and Nb additions increase hardenability by lowering the austenite transformation temperatures, resulting in finer microstructures and greater hardness for all cooling rates. Alloying additions have a greater effect on hardenability for larger austenite grain size. In the deformed specimens, it was found that Mn and Nb additions do not substantially decrease the austenite decomposition temperatures, which may be related to the differences in grain size and available solute Nb after deformation. Despite this, alloying additions in the deformed samples promote refined microstructures with increased hardness for all tested cooling rates. For both nondeformed and deformed conditions, Mn as well as Nb additions are suitable to increase hardenability. |
| 2 p.m. | Break |
| 2:20 p.m. | A Review of Nb Metallurgy and Optimum Alloy Design Solutions for the Production of Reinforcement Bars via Different Processing Routes Joao Souto, CBMM Niobium (Nb) microalloying has traditionally been associated with low-carbon flat products processed via thermomechanical-controlled processing routes, where Nb's ability to condition austenite through strain-induced precipitation is most effective. However, in high-carbon long products (>0.20 wt. % C), the application of Nb metallurgy remains limited due to the reduced solubility of Nb in austenite, particularly when higher strength and low-temperature toughness properties are required. Recent industrial results have demonstrated successful alloy designs to produce reinforcing bars using low niobium additions (<0.015 wt. % Nb), achieving a refined recrystallized austenite structure through solute drag control. This paper summarizes recent findings and discusses the metallurgical background of existing reinforcement bar grades with Nb additions. It focuses on the solubility of niobium in rebar products with mixed microalloying strategies (Nb, V, Ti), steelmaking routes (basic oxygen furnace and electric arc furnace), as well as different rolling technologies (cold, hot or direct charging). |
| 2:40 p.m. | Effect of Vanadium Microalloying on Pearlite Transformation Kinetics and Microstructure in 1080 Wire Rod Steel Emmanuel De Moor, Colorado School of Mines The present contribution examines the effect of V microalloying on pearlite transformation kinetics and microstructure. Previous research shows that V improves the hardness and tensile strength of hypereutectoid steels. Industrial 1080 wire rod compositions, with and without 0.035 wt. % V, were analyzed using dilatometry and detailed microstructural characterization. Results showed that V slows the pearlite transformation and refines the pearlite interlamellar spacing. Proeutectoid grain boundary cementite formation was observed to be reduced with V alloying. Atom probe tomography was conducted to analyze V partitioning and VC precipitation. Partitioning of V into pearlitic cementite was shown to occur at transformation temperatures of 600°C and above while little to no partitioning of V and other alloying elements occurs at 550°C. VC precipitated within ferritic regions only at 650°C with no precipitation or clustering of V occurring at and below 600°C. |
| 3 p.m. | Low-Temperature Liquid Phase Stability in Medium-Carbon Boron Steels Zachary Tuhoski, Missouri University of Science and Technology Boron-bearing steel grades experience defects such as hot tearing during continuous casting due to boron segregation at grain boundaries and a solidification range that can extend to low temperatures. Regions of high boron concentration see a decrease in the solidus temperature, decreasing structural integrity of the cast slab. Thermodynamic modeling was used to predict pseudo-binary phase diagrams for boron-containing steels of interest to industry. Modeled solidus temperatures were compared to experimentally determined solidus temperatures using differential scanning calorimetry. |
| 3:20 p.m. | Break |
| 3:40 p.m. | Titanium Partitioning Between Slag and Steel During Ladle Refining Bryan Webler, Carnegie Mellon University This work investigates the thermodynamics and kinetics of titanium partitioning between slag and steel during ladle processing. Equilibrium thermodynamic calculations from different software and databases were compared to experimental results. Kinetic calculations were performed assuming mass transfer control. The results can be used to provide a better assessment of titanium fade or pickup during liquid steel refining prior to casting. |
| 4 p.m. | The Nb+Ti-IF Automotive Steel Practice of Production in Pansteel Steelmaking Plant Zhang Qiang, Pangang Group Panzhihua Steel ＆Vanadium Steel Co. Ltd. |
| 4:20 p.m. | Enhancing Steel Cleanliness and Castability in 38MnSiVS6 Microalloyed Steel Sudhanshu Telang, NecoIndia |
| 4:40 p.m. | The Different Stages of Niobium Precipitation in Cast Iron Alloys Hardy Morhbacher, Niobelcon BV Niobium microalloying to cast iron alloys with lamellar and nodular graphite was found to have various effects on their properties and performance. Niobium precipitates as NbC at three different stages: in full liquid, during solidification and in full solid phase. The size, spatial distribution and particle morphology are markedly different at either stage. The formation of primary niobium carbide being dispersed as macroscopic particles in the iron matrix significantly increases the wear resistance. Niobium precipitating during solidification facilitates the nucleation of graphite and refines the eutectic cell size. Niobium remaining in solid solution delays the phase transformation inducing refinement of pearlite and ultimately precipitates as nanosized particles; thereby the amount of niobium added is crucial regarding the formation of these different precipitates. This contribution describes the precipitation mechanisms based on solubility considerations, details the related effects on the microstructure and indicates perceived benefits in exemplary applications. |
Thursday, 5 June 2025 | |
| 7 a.m. | Plant Tour of Climax Molybdenum |