High Manganese Austenitic Steel Research Articles

Microstructure and cryogenic mechanical properties of dissimilar friction stir welding joints between nitrogen-alloyed CoCrFeMnNi high-entropy alloy and high-manganese austenite steel

The microstructures and cryogenic mechanical properties of dissimilar friction stir welding (FSW) joints between nitrogen-alloyed CoCrFeMnNi high-entropy alloys (HEAs) and Fe–32.1Mn–7.5Cr–0.6Mo–1.2 N steel were investigated. The results reveal that defect-free dissimilar joints can be achieved through FSW. Furthermore, the grains of nitrogen-alloyed CoCrFeMnNi HEAs in the stir zone of the dissimilar joint are significantly more refined than those of Fe–32.1Mn–7.5Cr–0.6Mo–1.2 N steel. Joint efficiency at room and low temperature both exceed 90% of the base metal. Moreover, the cryogenic yield and ultimate strength of the dissimilar joints are higher than those recorded at room temperature. The fracture position is at the heat-affected zone of HEAs under two temperature conditions.

Effect of final rolling temperature on the microstructure and properties of high-manganese austenitic low-temperature steel

The effect of final rolling temperature ranging from 962 to 696 °C on as-rolled high-Mn austenitic low-temperature steel was investigated using scanning electron microscopy, electron backscatter diffraction, transmission electron microscopy, and X-ray diffraction. The microstructure of the experimental steel remained austenite without suffering ferrite phase transformation, even when produced with a final rolling temperature as low as 696 °C. A decrease in the final rolling temperature of the steel was accompanied by a decrease in grain size from 20.2 to 6.0 μm, accompanied by an increase in dislocation density from 3.01 × 1014 to 10.9 × 1014 m−2. In addition, M23C6 carbides precipitated at the grain boundaries when the final rolling temperature was below 782 °C. Grain refinement and increased dislocation density significantly enhanced the strength of the material. However, an increase in the intragranular dislocation density compromised grain deformation ability. Moreover, the precipitation of M23C6 reduced the plasticity and toughness of the material. Considering the balance between yield strength and low-temperature toughness, the optimal final rolling temperature was 898 °C; this produced a material with a yield strength of approximately 507 MPa and a low-temperature impact energy absorption of approximately 143 J.

Micromechanism insights and constitutive modeling for deformation in a novel high manganese austenitic steel

We explore the mechanical behavior and microstructural evolution of a novel high manganese austenitic steel (HMAS), extensively applied in underground engineering and structural construction. Our investigation focuses on two variants of HMAS, namely HMAS-1.9 and HMAS-10, which exhibit distinct yield strengths and elongation behaviors. Electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were employed to elucidate the evolution of microstructures during plastic deformation. Based on these experimental results, we developed a new phenomenological multiscale constitutive model that captures the mechanical behavior of HMAS, integrating micromechanisms and microstructural evolutions. Optimized with the MATLAB genetic algorithm toolbox, this model was successfully implemented in a uniaxial tensile finite element model (FEM) within ABAQUS, proving its efficacy in predicting both macroscopic flow stress and microstructural evolutions. Our findings highlight the important roles of initial grain size, dislocation density, and twin fraction in determining the mechanical properties of HMAS. Throughout the deformation process, both HMAS variants demonstrate similar plastic deformation behaviors, characterized by comparable rates of increase in dislocation density and twinning fraction, accompanied by a consistent trend of grain refinement. These findings not only deepen our understanding of the complex relationship between microstructure and mechanical properties of the HMAS steel, but also provide an effective multiscale constitutive modeling approach for predicting its deformation behavior.

The Dominant Role of Recrystallization and Grain Growth Behaviors in the Simulated Welding Heat-Affected Zone of High-Mn Steel.

Single-pass-welding thermal cycles with different peak temperatures (Tp) were reproduced by a Gleeble 3800 to simulate the heat-affected zone (HAZ) of a Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) high manganese austenitic steel. Then, the effect of Tp on the microstructure and mechanical properties of the HAZ were investigated. The results indicate that recrystallization and grain growth play dominant roles. Based on this, the HAZ is proposed to categorize into three zones: the recrystallization heat-affected zone (RHAZ) with a Tp of 700~900 °C, the transition heat-affected zone (THAZ) with a Tp of 900~1000 °C, and the coarse grain heat-affected zone (CGHAZ) with a Tp of 1000~1300 °C. The recrystallization fraction was 29~44% in the RHAZ, rapidly increased to 87% in the THAZ, and exceeded 95% in the CGHAZ. The average grain size was 17~19 μm in the RHAZ, slightly increased to 22 μm in the THAZ, and ultimately increased to 37 μm in the CGHAZ. The yield strength in the RHAZ and THAZ was consistent with the change in recrystallization fraction, while in the CGHAZ, it satisfied the Hall-Petch relationship with grain size. In addition, compared with the base material, the Charpy impact absorbed energy at -196 °C decreased by 22% in the RHAZ, but slightly increased in the CGHAZ. This indicates that the theory of fine grain strengthening and toughening is not entirely applicable to the HAZ of the investigated high-Mn steel.

Key role of gradient-nanostructure and extremely thin amorphous passive film on tribocorrosion behavior of a novel Cr+N alloyed high-Mn austenitic steel

High manganese steel is influenced by the combined effects of corrosion and wear during service under specific conditions, resulting in components with shortened service life. Under harsh service environments, newly developed Cr+N alloyed austenitic high manganese steel (Mn18Cr7C0.6N0.2 steel) as a new type of railway steel has shown promising results. Herein, the tribocorrosion behaviors of Mn18Cr7C0.6N0.2 and Mn13C1.1 steels in artificial acid rain were studied using electrochemical methods, field emission scanning electron microscope (FE-SEM), focused ion beam scanning electron microscopy (FIB-SEM), scanning transmission electron microscopemicroscopy energy dispersive X-ray spectroscopy (STEM-EDS), and high resolution transmission electron microscopy (HR-TEM). The results showed the formation of passive film and gradient-nanostructure on surfaces of both test steels during tribocorrosion. A dense and tightly adhering amorphous passive film was formed on Mn18Cr7C0.6N0.2 steel surface with a superior blocking effect toward invasive ions. The high strain resistance and plasticity of the Mn18Cr7C0.6N0.2 steel resulted in an intact gradient-nanostructure, suitable for obtaining high surface hardness and maintaining the toughness of the matrix, contribute to providing high wear resistance. The oxide film on the Mn13C1.1 steel surface comprised crystal α-FeOOH. Vortex cracks formed in its gradient structure due to strain localization. Meanwhile, the relatively poor corrosion protection ability and vortex cracks of its gradient-nanostructure prevented it from maintaining interface integrity of the gradient nanostructure, resulting in inferior tribocorrosion resistance. In artificial acid rain, the new type of Cr+N alloyed Mn18Cr7C0.6N0.2 steel exhibited higher tribocorrosion resistance than traditional high manganese steel, promising for use as an excellent wear-resistant material under corrosive environments.

Interaction of erosion and corrosion on high-strength steels used for marine dredging engineering

In this work, the erosion–corrosion performances of three high-strength steel samples: high manganese austenitic steel (HMnS), dual-phase steel (D-PS), and martensitic steel (MS), which are potentially used to construct marine dredged pipelines were investigated in comparison to the Q235 carbon steel. The corrosion-enhanced erosion (C-E) and erosion-enhanced corrosion (E-C) were electrochemically studied in conjunction with surface and subsurface characterizations. Results showed that the fracture of the steel extrusions induced by micro-cutting was the main erosion-corrosion feature under normal sand impacts. The C-E played a significant role in the erosion–corrosion process, which resulted in the dissolution of the work-hardening layer and facilitated the subsurface crack propagation, particularly for D-PS and MS. Although the general E-C rate was low, the concentration of the major anodes at the highly eroded area significantly enhanced the erosion process. Evaluating erosion resistance solely based on hardness is significantly limited. The twinning deformation of the austenite grain in HMnS effectively hindered the crack propagation during the erosion–corrosion. The addition of Al and Cr elements improved the erosion–corrosion resistance of high-strength steels.

Welding Processing of Medium-Manganese Austenitic Steels for Cryogenic Applications

Abstract For several years, the significance of gaseous energy sources (e. g. liquified natural gas and hydrogen) has been increasing worldwide due to environmental and climate policy requirements. Storage and transportation of the liquids occur under cryogenic conditions. This results in specific requirements for the mechanical properties of the materials used at cryogenic temperatures. Nowadays, cold-tough, high-nickel austenites and martensitic steels of type X8Ni9 are used for such purposes. While austenitic materials offer good processing properties, they are not attractive due to their comparatively low strength and high costs. Welding martensitic steel with commonly used nickel-based additives significantly impacts processing quality and process automation due to high magnetic remanence. Additionally, the increased requirements for the storage of liquid hydrogen regarding low-temperature toughness push the conventional low-temperature materials to their limits. A potential solution to the identified challenges can be achieved by using medium- and high-manganese austenitic steels. Within the scope of this work, the medium-manganese steel X2CrMnNiN1775 (1.4371) is investigated as an economical substitute for the conventionally used materials in cryogenic applications. Considering the relevant qualification requirements for welded joints and welding additives, submerged arc welded joints are investigated and their applicability under cryogenic operating temperatures is demonstrated.

An approach to calculating the casting temperature of high-manganese austenite steel

An approach to calculating the casting temperature of high-manganese austenite steel

Developing austenitic high-manganese high-carbon steels for biodegradable stent applications: Microstructural and mechanical studies

Fully degradable stents that temporarily support healing tissue can solve potential long-term complications associated with permanent implants. In this study, we investigate austenitic high-manganese high-carbon steels as promising candidates for such biodegradable stent applications. The microstructural characteristics and mechanical properties of the Fe–Mn–C steels were systematically analysed to assess their suitability for this purpose. A series of four austenitic Fe–Mn–C steels with varying manganese (15 and 30 wt%) and carbon (0.6–1.0 wt%) content were processed by vacuum induction casting, annealing and hot forging. Microstructural analysis was performed, and the hot forged materials were further evaluated using ultrasound, macro hardness, and (stopped) quasi-static tensile tests to assess stent-related parameters. In contrast to the as-cast state, the hot forged steels exhibited high chemical homogeneity, as was found by energy-dispersive X-ray spectroscopy (EDXS). Electron backscatter diffraction (EBSD) revealed comparability between the four steels regarding their annealing twin fractions and grain size distributions. An austenitic microstructure was revealed for all modifications by transmission X-ray diffraction (XRD), except Fe–15Mn–0.6C, which displayed a minor ε–martensite fraction. Reducing manganese from 30 to 15 wt% resulted in favourable effects, including a higher Young's modulus, lowered offset yield strength, and an increased ultimate tensile strength due to larger strain hardening while preserving a high total elongation. However, reducing the carbon content to 0.6 wt% diminished the mechanical performance due to reduced solid solution strengthening and the ε–martensite formation. Among the investigated steels, the novel Fe–15Mn–0.8C alloy exhibited the most attractive combination of the studied properties for potential stent applications.

Determination of rational heat treatment modes for new high-manganese austenitic steel using thermodynamic modeling

Determination of rational heat treatment modes for new high-manganese austenitic steel using thermodynamic modeling

Study on Characteristics of Through-Thickness Crack When Cryogenic Materials are Applied to Independent B Type Tank

Due to climate change, interest in eco-friendly energy is continuously increasing around the world. LNG is an intermediate energy source and its use increases continuously because of its established infrastructure. LNG temperature is -165°C and requires low temperature toughness of tank material. High manganese austenitic steel has similar mechanical properties to cryogenic material for LNG listed in IGC and IGF code. High manganese austenitic steel easily satisfies the low temperature toughness required at cryogenic temperature and shows superior performance in yield strength, tensile strength and elongation, compared to existing materials in IGC and IGF code.</br>In this study, the thickness ratio is reviewed while loading the same LNG fuel. Based on the thickness ratio, the thickness for 9%Ni steel, STS304 and Al5083 is calculated for two standard thickness of 10 mm and 20 mm for the high manganese austenitic steel. 9%Ni steel, STS304, Al5083 and high manganese austenitic steel are compared and reviewed from the viewpoint of the required time for initial surface cracks to grow into through-thickness cracks and the size of through-thickness cracks under the same amount of LNG fuel. The effect of different thickness, welded joint and stress sequence on through-thickness cracks are investigated.

FRACTURE SAFETY OF LIQUEFIED NATURAL GAS TANK IN CRYOGENIC CONDITIONS

High-manganese austenitic steel has been developed as a new cryogenic steel for application in liquified natural gas (LNG) storage and fuel tanks, with improved fracture toughness and safety at cryogenic temperatures. Generally, the fracture toughness decreases at lower temperatures; therefore, cryogenic steel requires a high fracture toughness to prevent unstable fractures. This study conducted unstable ductile fracture tests with 30-mm-thick high-manganese austenitic steel and evaluated its applicability to LNG storage and fuel tanks. The ductile fracture resistance in the weld joints was evaluated, including the weld metal and heat-affected zone. The unstable fracture resistance was evaluated for different LNG tank types. It was found that high-manganese austenitic steel has excellent unstable fracture characteristics and good material performance as a cryogenic steel; therefore, it can be applied in LNG storage and fuel tanks.

The influence of recrystallization annealing time on high cycle fatigue behavior of high-Mn austenitic steel at 77 K

Three high manganese austenitic steels were prepared by different recrystallization annealing time (0, 32, and 128 min) to investigate the effect of recrystallization annealing time on high-cycle fatigue behavior at 77 K. The microstructure was characterized by means of quasi in situ scanning electron microscope (SEM). When fatigue life is about 5.0 × 106 loading cycles, the fatigue strength at 77 K increases from 512 MPa to 625 MPa with the decrease in recrystallization annealing time (RAT). Decrease in RAT leads to grain refinement and the increase in density of dislocation. Grain refinement can delay crack initiation, prevent crack propagation, and hardly hinders the formation of deformation twins. In addition, it is surprising that the grain refinement and the increase in dislocation density promote the formation of nanoscale voids, which leads to stress relaxation and thus improve the fatigue performance.

THE EFFECT OF CARBON AND NEGATIVE TEMPERATURE ON THE PHYSICAL, MECHANICAL AND OPERATIONAL PROPERTIES OF AUSTENITIC HIGH-MANGANESE STEEL

Purpose. It consists in determining the influence of carbon and manganese, concentrations of modifiers, test temperatures on the physical and mechanical properties and wear resistance of austenitic highmanganese steel Г13Л.
 Research methods. Determination of impact viscosity was carried out on the MK-30A pendulum probe, microhardness – on the PMT-3 device. The hydrostatic weighing method was used to determine the density. Microstructural analysis and study of non-metallic inclusions were carried out using metallographic and electron microscopes. Corrosion resistance was determined in a model environment with pH9, which corresponded to the production conditions of beneficiation processes of ferrous and non-ferrous metallurgy.
 Results. It was established that the best indicators of the properties of steel 110Г13Л are provided at average values of carbon and manganese concentrations within the standard. For parts that work under low shock loads, it is advisable to use austenitic wear-resistant steels with lower manganese concentrations and higher carbon concentrations within the standard chemical composition.
 Scientific novelty. New dependences on carbon influence, structural modification, non-metallic inclusions, and physical and mechanical properties of high-manganese steel were clarified and obtained. The strength limit of steel increases monotonically with increasing carbon content, and the dependences describing changes in plasticity, impact toughness, and hardness are extreme in nature.
 Practical value. A rational method of modification to improve the operational characteristics of steels is proposed. The influence of the test temperature on the impact toughness of steel with changes in carbon concentrations was studied, as the main indicator of the reliability of machine parts at low temperatures.

Study on the role of cryogenic treatment on corrosion and wear behaviors of high manganese austenitic steel

In this study, electrochemical corrosion and wear experiments were conducted to clarify the role of cryogenic treatment on the microstructural morphology and resistance to corrosion and wear of high-manganese austenitic steel. Heat treatment of the solution (950 °C) and annealing (500 °C and 600 °C) were performed on the hot-rolled specimens. Cryogenic treatment was applied to hot-rolled, hot-rolled + heat treated specimens. Cryogenic treatment is a practical technology for eliminating the strip morphology of hot-rolled specimens and improves the wear resistance of heat-treated specimens. However, it plays different role on the corrosion resistance of tested specimens related with production process. The wear mechanism differs due to the cryogenic treatment. A schematic model of the wear mechanism is proposed based on the experimental results. Cryogenic treatment coarsens the grain size regardless of the production process.

Study on the Novel High Manganese Austenitic Steel Welded Joints by Arc Welding for Cryogenic Applications of LNG Tanks

The novel high-Mn austenitic steel is becoming a promising steel for cryogenic applications of LNG tanks. The welded joints take a critical role in cryogenic service for storage tanks. In this work, we developed well-matched high-Mn welding consumables and prepared the welded joints by shielded metal arc welding (SMAW), submerged arc welding (SAW) and gas tungsten arc welding (GTAW). The detailed welding parameters were proposed first, then the welding quality, mechanical properties, and microstructure were investigated. The results show that good welding quality, excellent mechanical properties, and stable levels of mechanical properties were obtained for high-Mn steel welded joints using similar welding consumables, the solid core of electrodes, and solid welding wires. Notably, the lowest cryogenic absorbed energy was found at 5 mm away from the fusion line rather than at the fusion line. The hardness of the welded joints was detected to be less than 280 HV due to the whole austenitic microstructure.

Macroscopic and nanoscale investigation of the enhanced wear properties of medium-Mn steel processed via room-temperature quenching and partitioning

High-manganese austenitic and high hardness martensitic steels are widely used in wear-related applications. However, their abrasive wear performance is unsatisfactory because of the insufficient twinning induced plasticity effect of the former and the weak strain hardening and low crack resistance during wear of the latter. Here, novel wear-resistant steels were developed via alloy design and simple room-temperature quenching and partitioning (RT-Q&P) of medium Mn steels (0.3C–10Mn and 0.3C–10Mn-0.25V). Their microstructure and sliding abrasive wear behavior were compared to those of conventional Hardox400 and Hadfield steels. The two medium-Mn steels had better wear properties than conventional wear-resistant steels. Moreover, the V-containing steel with a multiphase microstructure of tempered martensite, retained austenite, and nano-vanadium carbide precipitates, possessed 2.98 and 3.45 times higher abrasive wear resistance than the Hardox400 and Hadfield steels, respectively. Besides the stimulated transformation-induced-plasticity effect in RT-Q&P steels, the enhanced abrasive wear resistance of V-containing steel was attributed to microstructural refinement and improved strain hardening during wear imparted by V element. The main wear mechanism of RT-Q&P wear-resistant steels was cutting, while it was grooves and pits for Hadfield steel, and peeling pits and delamination for Hardox400 steel. This study can guide the design of structural materials with excellent wear resistance through multiphase microstructural and nano-precipitate regulation to overcome the wear challenges of components.

Synergistic effect of grain size and second-phase particle on the oxidation behaviour of a high-manganese austenitic heat-resistant steel

The effect of grain size and second-phase particles on the oxidation behaviour of a high-manganese austenitic (HMA) heat-resistant steel are investigated. Four HMA steels with controlled grain size and volume fraction of second-phase particles are prepared and then exposed at 1023 K in air for 400 h. The results show that the particle-reinforced HMA heat-resistant steels exhibit excellent oxidation resistance. A physical model was proposed to investigate the synergistic effect of grain size and second-phase particle on the oxide scale evolution in HMA steels. The presence of second-phase particles can significantly reduce the effective grain size for the oxide scale formation by providing diffusion channels. Therefore, the formation of nodular oxide and the occurrence of internal oxidation are effectively inhibited in the particle-reinforced heat-resistant steels.

HOT DUCTILITY BEHAVIOR OF Fe-0.05C-24Mn-3.5Si-1.6Al STEEL WITH Nb AND Ti MICROADDITIONS

"Hot ductility tests were carried out on Fe-0.05C24Mn-3.5Si-1.6Al high-manganese austenitic steel with Nb and Ti microadditions at a concentration of 0.029% and 0.075%, respectively. Hot tensile tests were performed using Gleeble 3800 thermomechanical simulator on specimens with a diameter of 6 mm and 116.5 mm in length. Deformation was carried out in a temperature range from 1050 °C to 1200 °C with a strain rate of 2.5 · 10-3 s -1 and 5.0 · 10-3 s -1 . Hot ductility was determined on the basis on evaluation of reduction in area (RA). Higher values of stress on the work-hardening curves were observed during tension carried out at higher strain rate. An analysis of the form and course of curves obtained in the tensile test allows to state that, in the studied range of hot plastic deformation parameters, the decrease of strain hardening is caused by the process of dynamic recrystallization (DRX). The reduction in area in a temperature range from 1050 °C to 1200 °C decreases from 90% to approx. 58% for the strain rate of 2.5 · 10-3 s -1 and from 82% to 48% – for the strain rate of 5.0 · 10-3 s -1 ."

Susceptibility of High-Manganese Steel to High-Temperature Cracking.

Tests were carried out on two high-Mn steels: 27Mn-4Si-2Al-Nb with Nb microaddition and 24Mn-3Si-1.5Al-Nb-Ti with Nb and Ti microadditions. High-manganese austenitic steels, due to their good strength and plastic properties belong to the AHSS (Advanced High-Strength Steel) group and are used in the automotive industry. The main difficulties faced during the casting of the steel and hot working are hot cracks, which can appear in the surface of the ingot. Cracks on the edges of the sheet after hot rolling are the reason for cutting the edges of the sheet and increasing production costs and material losses. The main reason for the formation of hot cracks is the decrease in metal ductility in the high-temperature brittleness range (HTBR). The width of the HTBR depends on mechanical properties and microstructural factors, i.e., non-metallic inclusions or intermetallic phases at austenite grain boundaries. In this paper, a hot tensile test was performed. The research was performed on the GLEEBLE 3800 thermomechanical simulator. This test allows us to determine the width of the high-temperature brittleness range (HTBR), the Nil Strength Temperature (NST), the Nil Ductility Temperature (NDT), and the Ductility Recovery Temperature (DRT). Hot ductility was determined from the value of the reduction in area R(A). The obtained results make it possible to determine the temperature of the beginning of hot working from the tested high-Mn steels. Fractographic research enabled us to define mechanisms of hot cracking. It was found that hot cracks form as a result of disruptions in the liquid film on crystals' boundaries.