Search

Due to the process complexity of the high‐carbon high‐manganese steel (HMnS) in casting and arc welding, this article propose the coaxial powder‐feeding laser cladding (LC) of HMnS coating using self‐developed HMnS powders. Firstly, high‐carbon HMnS coatings are prepared on the 16Mn substrate using coaxial powder‐feeding LC technology. It has a single austenite phase, without large defects such as pores and cracks. Then, ultrasonic shock peening is used to harden the HMnS coating, and the mechanical properties such as microhardness, impact toughness, wear and tensile properties are measured, which prove that HMnS coating has excellent working hardening, plasticity, toughness, and wear resistance properties. Finally, transmission electron microscopy is used to investigate the coupling effects such as dislocations, multiple twinning, and stacking faults on the HMnS coating after tensile fracture (true strain 39.2%). The deformation strengthening mechanism based on the dynamic Hall–Petch effect is revealed. The research results provide a new method for the preparation of high‐carbon HMnS coatings, and a new idea for expanding the application of high‐carbon HMnS. [ABSTRACT FROM AUTHOR]

It is imperative to ensure an even distribution of refined precipitates to enhance wear resistance. Herein, different heat treatments are to control the size and distribution of precipitates. The treatments include water quenching at 1100 °C followed by aging at 400 °C for 24, 60, and 84 h, designated as AT24, AT60, and AT84, respectively. The microstructure, mechanical properties, and impact wear properties of high‐manganese steel are investigated under solution and aging conditions using scanning electron microscopy, field‐emission scanning electron microscopy, tensile testing, and impact abrasive wear testing. Notably, the absence of nanoscale precipitates largely accounts for the poor wear resistance of as‐casting steel, whereas the strengthening effect of larger micrometer‐sized precipitates is insufficient. After the solution and aging treatment, nanosized precipitates continuously form within the matrix, conducive to the formation of the deeper work‐hardening layer, thereby improving the wear resistance. The fine micrometer‐sized precipitates and evenly distributed nanoscale precipitates in AT60 actively contribute to toughness. Additionally, these precipitates interact with slip dislocations, providing stronger strengthening via the Orowan looping mechanism. The wear mechanisms of steel can be transformed from wide, deep pits to shallow grooves and microcutting by extending the aging time. [ABSTRACT FROM AUTHOR]

As an alloying element in steel, manganese can considerably enhance the mechanical properties of structural steel. However, the Mn volatilisation loss in vacuum melting is severe because of the high saturated vapour pressure, resulting in an unstable Mn yield and Mn content fluctuation. Therefore, a systematic study of the volatilisation behaviour of Mn in vacuum melting is required to obtain a suitable Mn control process to achieve precise control of Mn composition, thereby providing a theoretical basis for industrial melting of high-Mn steel. In order to explore the Mn volatilization behavior, the volatilization thermodynamics and volatilisation rate of Mn, as well as the influence factors are discussed in this study. The results shows that Mn is extremely volatilised into the vapour phase under vacuum, the equilibrium partial pressure is closely related to Mn content and temperature. With an increase in the Mn content, a higher C content has a more obvious inhibitory effect on the equilibrium partial pressure of Mn. The maximum theoretical volatilisation rate of Mn shows a linear upward trend with an increase in Mn content. However, a higher C content has a more obvious effect on the reduction of the maximum theoretical volatilisation rate with the increase of Mn content. This study provides an improved understanding of Mn volatilisation behaviour as well as a theoretical foundation for consistent Mn yield control during the vacuum melting process of high-Mn steel.

A new hardfacing alloy within the Fe-Ti-Nb-Mo-V-C alloying system was utilized to restore the working surfaces of cone crusher rotors using Flux-Cored Arc Welding (FCAW). TiC, NbC, Mo2C, VC, Mn, and ferromanganese powders were selected as the base materials for manufacturing the welding wire. The resulting hardfaced layer exhibits a composite structure, with manganese austenite as the matrix and complex solid solution reinforcements with a NaCl structure, closely resembling the formula (Ti0.3Nb0.3Mo0.3)C. The primary advantages of this hardfacing alloy include its capacity for intensive deformation hardening along with high abrasion resistance. The hardness of the hardfaced layer is approximately 47 HRC in the as-deposited state and increases to around 57 HRC after work hardening, surpassing typical hardfacing alloys derived from high manganese steel by about 10 HRC. The efficacy of the alloy was tested in restoring rotors made of Hadfield steel in a PULVOMATIC series crusher model 1145, during the milling of sand-gravel mixtures ranging from 25 to 150 mm into spalls measuring 5 to 20 mm. With an average productivity of approximately 60 tons per hour and a production volume of 300 tons, the utilization of this hardfacing alloy enabled multiple restorations of the rotor while maintaining productivity at a level of 15 thousand tons of spalls.

The aim of the work was to determine the effect of Ti micro-addition on the hot tensile behaviour, microstructure and fractography of two low-C high-manganese steels with additions of Si and Al. The hot tensile tests were performed using the Gleeble 3800 thermomechanical simulator. Samples were stretched at a temperature range from 1050 ℃ to 1200 ℃ at a strain rate of 2.5·10 3 s−1. The microstructure of the tested high-manganese steels under conditions of hot deformation was influenced by strain hardening and simultaneous dynamic recrystallization, as well as precipitation processes-depending on the chemical composition of the alloy and plastic deformation parameters. The analysis of the curves registered in the hot tensile tests indicated that a decrease of strain hardening was the result of the dynamic recrystallization. Hot tensile curves of the Ti-micro-alloyed steel were characterized by higher yield stress compared to the Ti-free steel. The Ti micro-addition with a concentration of 0.075 wt.% guaranteeing stable TiN-type nitrides eliminated the possibility of precipitating AlN-type nitrides and complex MnS-AlN type non-metallic inclusions, which are harmful to hot ductility. Fracture modes of the Ti-free steel showed a mixed nature from 1050 ℃ to 1150 °C, i.e. ductile fracture and numerous cavities and voids were identified. As the deformation temperature increased to 1200 °C, the fracture character was brittle with numerous inter-crystalline cracks along austenite grain boundaries. The addition of Ti improved significantly the hot ductility behaviour characterized by higher values of flow stress and reduction in area as well as ductile fracture modes in the entire high deformation temperature range. [ABSTRACT FROM AUTHOR]

High-manganese austenitic steel represents an innovative variety of low-temperature steel used in the construction of liquefied natural gas (LNG) storage tanks. This steel boasts remarkable characteristics such as exceptional plasticity, superior toughness at cryogenic temperatures, and robust fatigue resistance, all while providing significant cost benefits. By utilizing high-manganese steel, the material manufacturing costs can be considerably lowered, simultaneously ensuring the long-term stability and safety of LNG storage tanks. The alloying design is pivotal in attaining superior performance in high-manganese steel. Choosing the right chemical components to control the stacked fault energy (SFE) of high-manganese steel and fine-tuning its structure can further improve the balance between strength and plasticity. Summarizing the advancements in alloying design for high-manganese steel is of great importance, as it offers a foundational dataset for correlating the chemical composition with the performance. Therefore, this paper outlines the deformation mechanisms and the principles of low-temperature brittleness in high-manganese austenitic steel, and from this foundation, it explicates the precise functions of alloying elements within it. This aims to provide a reference for future alloying designs and the industrial deployment of high-manganese steel in LNG storage tanks. [ABSTRACT FROM AUTHOR]

To address the limited wear resistance attributed to the insufficient initial mechanical properties observed in high manganese steel (HM) wear behavior, we introduced nitrogen (N) to modulate precipitation behavior, thereby elevating material mechanical properties and wear resistance, and this was further enhanced through aging treatments. Due to the nitrogen addition, the precipitates transformed from MC to M(C, N), concurrently triggering a substantial increase and refinement in precipitates. As a result, nitrogenous high manganese steel (NHM) exhibited improved strength, toughness, and work-hardening capacity. The enhancements amounted to 67–77 MPa in yield strength and 5.3–9.3 % in elongation, with these improvements becoming more pronounced after extending the aging treatment. Under impact abrasive wear conditions, the NHM demonstrated the development of a stable work-hardened layer. The NHM hardened layer rapidly reached a depth of 4–6 mm, effectively resisting abrasive embedding and suppressing matrix abrasion. This transitioned the primary wear mechanisms from cutting and plowing to plastic deformation and micro-spalling. Additionally, NHM's great uniformity and toughness-plasticity played a crucial role in preventing the initiation and propagation of fatigue cracks and fatigue sheds.

This study investigates the effects of laser deposition and laser rescanning (LR) on the microstructure and mechanical properties of high-manganese steel (HMnS) deposited by laser-directed energy deposition (L-DED) comprising 24 wt.% Mn. Four types of laser deposition and LR strategies were investigated: unidirectional L-DED scanning without laser rescanning, L-DED scanning with 90° alterations in the laser scanning path on each layer without laser rescanning, unidirectional L-DED with laser rescanning in the same direction, and L-DED with laser rescanning with 90° alterations in the laser scanning path. The L-DED-processed HMnS had only a few small pores and exhibited a microstructure without any serious defects such as cracks. Additionally, a strong fibrous texture along the <101>/building direction of the fully austenite phase was found. The mechanical properties (microhardness and tensile strength) of HMnS were improved by the LR with a grain refinement effect and fine solidification cell size due to the significantly faster solidification rate in LR than that in L-DED. [ABSTRACT FROM AUTHOR]

The excellent strain hardening behavior of high-manganese steel (HMnS) makes it widely used under strong impact and heavy wear conditions. However, the rapid hardening ability of HMnS needs to be improved under low stress. In this paper, laser remelting technology (LRT) was proposed to improve the hardening ability of HMnS under low stress. Firstly, the surface of HMnS was treated by LRT, and its surface and internal microstructure were characterized by a 3D profiler, an x-ray diffractometer, a scanning electron microscope (SEM) and an energy-dispersive spectrometer. Then, the microhardness and wear test were carried out by using a Vickers hardness tester and a wear tester, and the sub-surface microstructure and surface wear scars were tested by SEM and 3D profiler to study the wear performance of HMnS before and after laser remelting. Finally, the hardening effects and wear mechanism of laser-remelted high-manganese steel (LR-HMnS) were revealed. It was found that heterogeneities of LR-HMnS were composed of columnar structures, equiaxed structures and segregation region. These heterogeneities were conducive to improving the hardening ability of HMnS under low stress conditions, which could improve its wear resistance. [ABSTRACT FROM AUTHOR]

To address global environmental concerns and reduce carbon dioxide emissions, countries worldwide are prioritizing the development of green, eco-friendly, and low-carbon energy sources. This emphasis has led to the growing importance of promoting clean energy industries like hydrogen energy and natural gas. These gases are typically stored and transported at cryogenic temperatures, making ultra-low temperature alloys indispensable as essential materials for the storage and transportation of liquid gas energy. With the temperature decreasing from room temperature (RT) to liquid nitrogen temperature (LNT), the dominant deformation mechanism in high-manganese steels undergoes a transformation from dislocation slip to deformation twinning, resulting in exceptional cryogenic mechanical properties. Consequently, high-manganese steel has emerged as an excellent material candidate for cryogenic applications. This report focuses on establishing the composition of high-manganese steel suitable for cryogenic applications and provides a comprehensive review of its microstructure and mechanical properties at both RT and LNT. Furthermore, it offers a prospective outlook on the future development of cryogenic high-manganese steels. [ABSTRACT FROM AUTHOR]

High-manganese austenitic steel represents an innovative variety of low-temperature steel used in the construction of liquefied natural gas (LNG) storage tanks. This steel boasts remarkable characteristics such as exceptional plasticity, superior toughness at cryogenic temperatures, and robust fatigue resistance, all while providing significant cost benefits. By utilizing high-manganese steel, the material manufacturing costs can be considerably lowered, simultaneously ensuring the long-term stability and safety of LNG storage tanks. The alloying design is pivotal in attaining superior performance in high-manganese steel. Choosing the right chemical components to control the stacked fault energy (SFE) of high-manganese steel and fine-tuning its structure can further improve the balance between strength and plasticity. Summarizing the advancements in alloying design for high-manganese steel is of great importance, as it offers a foundational dataset for correlating the chemical composition with the performance. Therefore, this paper outlines the deformation mechanisms and the principles of low-temperature brittleness in high-manganese austenitic steel, and from this foundation, it explicates the precise functions of alloying elements within it. This aims to provide a reference for future alloying designs and the industrial deployment of high-manganese steel in LNG storage tanks.

To solve the ongoing problems of micro-alloyed Hadfield's steel, insufficient hardness and excessive deformation in the early working period, expensive alloying elements like Ti, Nb, and V have been utilized. However, traditional long-time, single-stage aging exacer-bates vanadium to assemble at the edge of initial precipitates, which diminishes estimated effects. For this, here we report the tremendous impact of retrogression and re-aging process (RRA) in this steel by booming the V (C, N) mean sized in 11 nm. The procedure enhances the micro-hardness, yielding strength, tensile strength, and impact-wear resistance for more than 27.4%, 29.5%, 22.2%, and 51.5%, respectively. Moreover, the wear mechanism of RRA samples has been investigated in that micro-sized precipitates surrounded by numerous nano V (C, N) stick in the matrix and hinder the abrasive embedding consistently, thus decreasing the micro-cutting and micro-plowing. This new process maximizes the utilization of costly and nonrenewable vanadium and magnifies the impact-wear resistance under either mild or medium-intensity working conditions.

Effects of reduced (– 40 °C), ambient (20 °C), and elevated (200 °C) deformation temperatures on the microstructure evolution and strain hardening behavior of two low-C thermomechanically processed high-manganese steels were studied. The microstructure was characterized by means of scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM) techniques. The temperature-dependent tendency of austenite to strain-induced ε/α′-martensitic transformation and mechanical twinning was qualitatively and quantitatively assessed using the EBSD technique. The steel containing 26 wt% of Mn showed the beneficial strength–ductility balance at reduced deformation temperature -40 °C due to the intense Transformation-Induced Plasticity (TRIP) effect which resulted in the formation of significant ε- and α′-martensite fractions during tensile deformation. The mechanical properties of steel containing 27 wt% of Mn were more beneficial at elevated deformation temperature 200 °C due to the occurrence of intense Twinning-Induced Plasticity (TWIP) effect expressed by the presence of significant fraction of mechanical twins. Moreover, at the highest deformation temperature 200 °C, the evidence of thermally activated processes affecting the mechanical behavior of the higher Mn steel was identified and described. [ABSTRACT FROM AUTHOR]

Copyright of Metallophysics & Advanced Technologies / Metallofizika i Novejsie Tehnologii is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigates the effects of laser deposition and laser rescanning (LR) on the microstructure and mechanical properties of high-manganese steel (HMnS) deposited by laser-directed energy deposition (L-DED) comprising 24 wt.% Mn. Four types of laser deposition and LR strategies were investigated: unidirectional L-DED scanning without laser rescanning, L-DED scanning with 90° alterations in the laser scanning path on each layer without laser rescanning, unidirectional L-DED with laser rescanning in the same direction, and L-DED with laser rescanning with 90° alterations in the laser scanning path. The L-DED-processed HMnS had only a few small pores and exhibited a microstructure without any serious defects such as cracks. Additionally, a strong fibrous texture along the /building direction of the fully austenite phase was found. The mechanical properties (microhardness and tensile strength) of HMnS were improved by the LR with a grain refinement effect and fine solidification cell size due to the significantly faster solidification rate in LR than that in L-DED.

To address global environmental concerns and reduce carbon dioxide emissions, countries worldwide are prioritizing the development of green, eco-friendly, and low-carbon energy sources. This emphasis has led to the growing importance of promoting clean energy industries like hydrogen energy and natural gas. These gases are typically stored and transported at cryogenic temperatures, making ultra-low temperature alloys indispensable as essential materials for the storage and transportation of liquid gas energy. With the temperature decreasing from room temperature (RT) to liquid nitrogen temperature (LNT), the dominant deformation mechanism in high-manganese steels undergoes a transformation from dislocation slip to deformation twinning, resulting in exceptional cryogenic mechanical properties. Consequently, high-manganese steel has emerged as an excellent material candidate for cryogenic applications. This report focuses on establishing the composition of high-manganese steel suitable for cryogenic applications and provides a comprehensive review of its microstructure and mechanical properties at both RT and LNT. Furthermore, it offers a prospective outlook on the future development of cryogenic high-manganese steels.

This study investigates the wear resistance of an Fe–12Mn–5Cr–1Ni-0.4C (high-manganese steel) produced by direct energy deposition (DED) and spheroidal graphite cast iron. The high-manganese steel was deposited on the spheroidal graphite cast iron substrate. Near the deposit/substrate interface, the graphite phases of the cast iron are completely solutionized owing to the low carbon content of the high-manganese steel. In addition, the steel was deposited with a dense microstructure without interfacial cracks owing to the strong austenite stabilization effect. The wear behavior for various wear loads and sliding speeds was studied using ball-on-disk tribology tests with counterpart balls (KS STB2 bearing steel). The results show that the wear rates of the deposited high-manganese steel and the spheroidal graphite cast iron depended more on the wear load than on the sliding speed. At a low wear load of 20 N or less, the spheroidal graphite cast iron showed a higher wear rate than the deposited high-manganese steel owing to the self-lubricating effect of graphite. When the wear load condition was 50 N, the high-manganese steel had a higher wear resistance than the cast iron owing to the work-hardening effect. Therefore, it is expected that high-manganese steels, produced by DED, with high wear resistance under a high wear load will be effective for repairing spheroidal graphite cast iron products.

Fe-30Mn-0.05C steel specimens with cold-rolled, partially recrystallized, fine-grained, and coarse-grained microstructures were fabricated by means of 80% cold rolling followed by annealing at 550–1000 °C. The initial and deformed microstructures were characterized, and the Charpy impact properties were tested at room temperature (RT) and liquid nitrogen temperature (LNT). It was found that the Charpy absorbed energy increased with the annealing temperature, while the specimens showed different trends: parabolic increase at RT and exponential increase at LNT, respectively. Compared with the fully recrystallized specimens, those with a partially recrystallized microstructure exhibited lower impact energy, especially at LNT. This was because cracks tended to nucleate and propagate along the recovery microstructure where stress concentration existed. The grain size played an important role in the twinning behavior and impact properties. High Charpy impact energy (~320 J) was obtained in the coarse-grained specimen having the grain size of 42.1 μm at both RT and LNT, which was attributed to the activation of high-density deformation twinning. However, deformation twinning was inhibited in the specimen with the average grain size of 3.1 μm, resulting in limited work hardening and lower impact energy. [ABSTRACT FROM AUTHOR]

In this paper, the heat generated during deformation under the static testing of high-manganese TWIP steel with addition of niobium was determined. The research combined the interaction of heat generated during deformation, mechanical properties, hardness and microstructure. Temperature and strain were measured simultaneously using infrared (IR) thermography and digital image correlation (DIC) method. The average temperature measured at the necked region equals 42°C at the strain rate of 0.001 s−1 and exceeds 100°C at 0.5 s−1. Therefore at large strains, a reduction in stress was observed. The course of the hardness change coincides very well with the strain changes, however, at the strain rate of 0.5 s−1 near to the necking area the hardness equals to 360 HV2, whereas at the lower strain rates it equals to 370 HV2. These changes are connected mainly with increase in temperature to >100°C [ABSTRACT FROM AUTHOR]

This work aims to describe the interfacial interaction at the interface between refractory material and high-manganese (XT 720) and structural (11 523) steel using a wetting test up to 1600 °C. The contact angles were determined through the sessile drop method, and the results were put into context through degradation testing and the characterization of the interfacial interface by Energy Dispersive X-Ray (EDX), X-Ray Diffraction (XRD) analyses, and Scanning Electron Microscopy (SEM). The lowest resistance to molten steel was observed for chamotte materials, while the highest was observed for materials based on electrofused corundum. High-manganese steel was strongly erosive to the materials tested, with the wetting angle decreasing significantly from 10 to 103° with decreasing Al2O3 content (an increase of 2.4 to 59.4% corundum) in the refractories. Structural steel showed wetting angles from 103 to 127° for identical refractories. These results were consistent with the average erosion depth for Mn steel (0.2–7.8 mm) and structural steel (0–2.4 mm). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The authors investigated tribological characteristics, phase composition of worn surfaces and microhardness of subsurface regions of WC–(Fe–Mn–C) composites with a two-phase (γ + α′) matrix containing 4 wt % Mn (WC–80G4), and a single-phase matrix of γ-iron containing 20 wt % Mn (WC–80G20) after sliding against a disk of high-speed steel at a contact pressure of 5 MPa and sliding speeds in the range from 10 to 37 m/s. The wear intensity of WC–80G4 and WC–80G20 increased with increasing sliding speed, while the wear rate of WC–80G20 at fixed sliding speeds was approximately three times higher than that of WC–80G4. The values of the friction coefficient decrease with increasing sliding speed in such a way that at fixed sliding speeds the values of the friction coefficient of WC–80G4 were lower than those of WC–80G20. The amount of mixed oxide FeWO4 formed during tribo-oxidation of the composites' worn surface increased with the sliding speed and was directly proportional to the wear intensity and inversely proportional to the friction coefficient values. At fixed sliding speeds tribooxidation of WC–80G4 leads to the formation of a larger amount of FeWO4 on the friction surface compared to the WC–80G20 composite. Indentation of worn surfaces with a Vickers pyramid showed that the nature of indentation resistance of tribolayers formed at high sliding speeds (30 m/s and 37 m/s) differs from that for tribolayers obtained at relatively low sliding speeds (10 and 20 m/s), namely, the friction surfaces after high sliding speeds were characterized by a more tough behavior. Measurement of microhardness values of the WC–80G4 and WC–80G20 composites obtained after indentation below tha worn surfaces recorded the fact of hardening of the near-surface regions of the WC–80G4 composites and, on the contrary, softening in the case of WC–80G20. Thus, under conditions of intensive heating and severe plastic deformation of the surface, structural-phase state of the substrate of WC–(Fe–Mn–C) composites, on which this viscous protective tribolayer is formed, turns out to be a very important factor. It is the two-phase (γ + α′) steel matrix that, under conditions of intensive frictional heating, provides the conditions for effective formation of a heterophase composite layer that reduces the friction coefficient and has a high resistance to fracture upon indentation. [ABSTRACT FROM AUTHOR]

Elastoplastic properties of tribological layers generated on WC–(Fe–Mn–C) composites with matrices composed of γ-iron containing 20 wt % Mn (WC–80G20) and of γ + α' with 4 wt % Mn (WC–80G4) after sliding against a high-speed steel disk at contact pressure of 5 MPa and sliding speeds in the range from 10 to 37 m/s have been investigated. It was established that the main factor determining the morphology of the worn surface is the sliding speed. At sliding speeds of 10 and 20 m/s, fine-grained mechanically mixed tribolayers of 3–4 µm in thickness formed. As the sliding speed increased to 30–37 m/s, the thickness of the tribolayers reached 10–15 µm, and the structure consisted of oxidized fragments of WC–(Fe–Mn–C) composites and FeWO4 complex oxide without any sharp boundary observed. Both highest values of nanohardness (~33 GPa) and effective Young's modulus (~523 GPa) were achieved on the WC–80G4 tribolayer after friction at 10 m/s when the nanoindentor indented agglomerates of fragmented WC grains. This contrasted with the properties of the tribolayers formed at sliding velocities above 20 m/s. The results of nanoindentation showed an obvious effect of tribochemically induced softening in the generated tribolayer after high-speed sliding at 37 m/s. Such a layer had a composite microstructure consisting of fragmented composite components cemented in-situ by tribochemically formed FeWO4 and, in addition to antifriction properties, had an increased indentation fracture resistance. [ABSTRACT FROM AUTHOR]

Carbon‐containing high‐manganese steels are susceptible to strain aging, which influences the mechanical properties during and after deformation. To understand the strain aging behavior of austenitic Fe‐22Mn‐1.3Al‐0.3C high‐manganese steel, dynamic as well as static strain aging are examined. Dynamic strain aging, occurring during deformation, is quantified by tensile tests at different strain rates. The strain localization during straining is analyzed by digital image correlation. A decrease in strain rate increases the tensile strength and influences the onset of a serrated flow. Static strain aging is quantified by interrupted tensile tests, combined with digital image correlation and small‐angle neutron scattering (SANS). The yield strength increases due to static strain aging at room temperature within the period of days. The samples show extended yield point (yield point elongation) and the effect strengthens at higher pre‐deformation. With SANS, evidence of carbon‐manganese ordering (C–Mn ordering) during aging is obtained and correlated. [ABSTRACT FROM AUTHOR]

Hot ductility tests were carried out on Fe-0.05C-24Mn-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. [ABSTRACT FROM AUTHOR]

Evolution of the microstructure of steel 110G13L under friction is studied using the method of synchrotron x-ray diffraction and subsequent profile analysis of the diffraction peaks. Friction of the high-manganese steel is accompanied by accumulation of crystal lattice defects, which finds reflection in changes in the full widths of half maximums. The experimentally determined structural defects are a result of growth of microdistortions of the austenite lattice and reduction of the sizes of coherent scattering domains. It is shown that the friction interaction produces anisotropic displacement of the diffraction maximums of the austenite, which indicates enhanced probability of formation of stacking faults and lowering of the stacking fault energy. Obvious features of mechanically induced phase transformations have not been detected. [ABSTRACT FROM AUTHOR]

The solidification microstructure of an Fe–Mn–C–Al high-Mn steel with added Nb was studied by optical microscopy and scanning electron microscopy. The results showed that the size of the columnar and equiaxed grains in the solidified structure of the high-Mn steel without added Nb was large. When Nb was added, the size of the equiaxed and columnar grains in the solidification structure of the high-Mn steel decreased. The twin-induced plasticity in the high-Mn steel with added Nb clearly refined the grain size of the solidified structure and simultaneously increased the equiaxed crystallization rate. The high-melting-point second-phase particles increased the heterogeneous nucleation rate, which was beneficial for grain refinement. A large amount of Nb precipitates from the solidification process increased the equiaxed crystallization rate of the solidified microstructure. The increased crystallization rate affected the growth direction of the columnar and equiaxed grains during solidification and indirectly decreased the probability of crack formation, which improved the quality of the twin-induced plastic steel.

Fe-30Mn-0.05C steel specimens with cold-rolled, partially recrystallized, fine-grained, and coarse-grained microstructures were fabricated by means of 80% cold rolling followed by annealing at 550–1000 °C. The initial and deformed microstructures were characterized, and the Charpy impact properties were tested at room temperature (RT) and liquid nitrogen temperature (LNT). It was found that the Charpy absorbed energy increased with the annealing temperature, while the specimens showed different trends: parabolic increase at RT and exponential increase at LNT, respectively. Compared with the fully recrystallized specimens, those with a partially recrystallized microstructure exhibited lower impact energy, especially at LNT. This was because cracks tended to nucleate and propagate along the recovery microstructure where stress concentration existed. The grain size played an important role in the twinning behavior and impact properties. High Charpy impact energy (~320 J) was obtained in the coarse-grained specimen having the grain size of 42.1 μm at both RT and LNT, which was attributed to the activation of high-density deformation twinning. However, deformation twinning was inhibited in the specimen with the average grain size of 3.1 μm, resulting in limited work hardening and lower impact energy.

This work aims to describe the interfacial interaction at the interface between refractory material and high-manganese (XT 720) and structural (11 523) steel using a wetting test up to 1600 °C. The contact angles were determined through the sessile drop method, and the results were put into context through degradation testing and the characterization of the interfacial interface by Energy Dispersive X-Ray (EDX), X-Ray Diffraction (XRD) analyses, and Scanning Electron Microscopy (SEM). The lowest resistance to molten steel was observed for chamotte materials, while the highest was observed for materials based on electrofused corundum. High-manganese steel was strongly erosive to the materials tested, with the wetting angle decreasing significantly from 10 to 103° with decreasing Al2O3 content (an increase of 2.4 to 59.4% corundum) in the refractories. Structural steel showed wetting angles from 103 to 127° for identical refractories. These results were consistent with the average erosion depth for Mn steel (0.2–7.8 mm) and structural steel (0–2.4 mm).

Due to pronounced work-hardening induced by the complex interplay of deformation mechanisms such as dislocation slip, twinning and/or martensitic phase transformation, high-manganese steels represent a class of materials well-suited for mechanical surface treatment. In the present study, the fatigue behavior of a high-mangsanese steel showing twinning-induced plasticity (TWIP) effect at room temperature (RT) was investigated after deep rolling at 550 °C. Results are compared to a former study discussing the behavior after RT deep rolling. Evolution of the near-surface microstructure was analyzed by scanning electron microscopy (SEM), microhardness measurements and residual stress depth profiles obtained by X-ray diffraction (XRD). Both uniaxial tensile tests and uniaxial tension-compression fatigue tests have been conducted in order to rationalize the macroscopic material behavior. Following deep rolling at 550 °C, SEM measurements employing electron backscatter diffraction (EBSD) revealed a heavily deformed surface layer as well as localized deformation twinning. Specimens showed inferior hardness and residual stress depth profiles when compared to RT deep rolled counterparts. Tensile tests indicated no difference between the conditions considered. Fatigue properties however were improved. Such behavior is rationalized by a more stable residual stress state induced by dynamic strain aging. [ABSTRACT FROM AUTHOR]

Ladle treatment technology is expected to be a new approach for prevailing over the hot crack susceptibility of conventional high-manganese steel. The liquefaction and solidification mechanisms of the conventional and ladle-treated high-manganese steel were detected by DTA. Their solidification structures were observed by optical microscope and scanning electron microscope. Multistage deformation process of the two steels was carried out by using thermomechanical simulator (Bahr TTS-820) from 700 to 1200 °C. In addition, their thermoplastic character was detected by dilatometer (DIL-805/D) from 800 to 1200 °C. On the other hand, TEM was used for explaining the nucleation of cementite and austenite at magnesium sulfide nuclei in ladle-treated high-manganese steel. The results refer to the peculiar microstructure after ladle treatment of high-manganese steel causes a great enhancement in the hot forming character of high-manganese steel in terms of crack susceptibility and flow stress. In addition, the good formability of the ladle-treated high-manganese steel was confirmed by comparing with the low-carbon steel at hot working temperatures. [ABSTRACT FROM AUTHOR]

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.

The present research is part of a project that includes several grades of high‑manganese steels with different chemical compositions and various pre-treatment parameters. The main objective of this work was to determine favourable conditions for the occurrence of strain-induced phase transitions in unstable Fe-20Mn-3Al-3Si steel. After preliminary treatment the steel showed a two-phase microstructure consisting of austenite matrix and 29% of ferrite volume fraction. The deformation process of the examined steel was strongly influenced by the low stacking fault energy value of austenite matrix. Initially, the slip of dissociated dislocations led to the formation of numerous bands of stacking faults. Then, the phase transformations induced by plastic deformation took place, i.e., γ (fcc) → ε (hcp) and subsequently ε (hcp) → α' (bcc). The beginning and further progress of these phase transitions depended primarily on the crystallographic orientations of the austenite grains. The more favourable the orientation of the grains with respect to external stresses, the more effective was the activation of dislocation slip and the greater number of deformation bands was formed. These processes directly resulted in a locally induced phase transition γ → ε. Simultaneously, in grains showing the formation of ε-bands in at least two intersecting systems, the transformation ε → α' gradually occurred. • Unstable austenite microstructure in two-phase Fe-Mn-Si-Al steel subjected to cold rolling. • Appearance of deformation induced transformations γ (FCC) → ε (HCP) and γ (FCC) → ε (HCP) → α' (BCC). • Occurrence of phase transformations in grains with the most favourable orientations for slip activation. • Development of preferential Shoji-Nishiyama and Kurdjumov-Sachs relationships between the phases. [ABSTRACT FROM AUTHOR]

Guide shoe made of steel is an important component of coalcutter and rail transport to sustain forward direction. However, the guide shoe suffers from wear failure due to the heavy load and fatigue. Preparing wear-resistance coating on the worn surface is a practical and economic technology to elongate longevity. High manganese steel is a candidate material with excellent wear resistance. In this study, high-manganese (HiMn) and high-manganese medium-chromium (HiMnMeCr) coatings are fabricated by using wire arc additive manufacturing (WAAM) to investigate the role of Cr addition on the microstructure and resistance to wear and corrosion by analyzing the microstructure morphology, wear rate, coefficient of friction, surface and cross-sectional morphology of the wear track, and electrochemical behavior by using sliding wear test and electrochemical experiment. The experimental results obtained by using the counterface material of ZrO 2 showed that Cr addition changed the microstructure constitutes of WAAMed HiMn coating from biphasic austenite + martensite to single austenite. The addition of Cr elongated the running-in period of the wear process and weakened the wear resistance of the WAAMed HiMnMeCr coating due to the work-hardening effect induced by the severe plastic deformation of austenite. At loads of 50 and 100 N, the primary wear mechanism for the HiMn coating was a complex mode of abrasive and adhesive wear. The wear mechanism transformed into a single adhesive wear at a load of 120 N. However, the primary wear mechanism of the HiMnMeCr coatings was abrasive wear at all tested loads. The electrochemical experiment (pote ntiodynamic curves and EIS analysis) shows that the corrosion resistance of HiMnMeCr coating was better than that of HiMn coating, indicating that the addition of Cr enhanced the corrosion resistance of the WAAMed HiMn steel by the passivation effect of Cr. This study will provide a fundamental theory for the fabrication of wear-resistance coating by using WAAM. • Cr addition elongates the running-in period of wear process. • Cr addition induces the work-hardening effect of high manganese steel due to microstructure difference. • The wear mechanism changes from abrasive and adhesive wear to single adhesive wear due to "work-hardening" effect. [ABSTRACT FROM AUTHOR]

Copyright of Electroplating & Finishing is the property of Electroplating & Finishing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Compression tests and metallographic observation were conducted to investigate the effect of temperature (400 °C–1100 °C), strain rate (0.001–10 s ^−1 ) and chromium content (0.21–5.44 wt.%) on the flow behavior of high manganese steels for cryogenic application. The results showed that the flow stress reduced with increased temperature and decreased strain rate. The effect of chromium content on the flow stress of steels was not linear. The lowest flow stress was got when the content of chromium was 1.53 wt.%. The influence of strain rate and temperature was obvious while that of chromium content was minor. The maximum flow stress decreased 538 MPa-571 MPa when the temperature rised from 400 °C to 1100 °C at the strain rate 10 s ^−1 . It ascended 146 MPa-149 MPa when the strain rate increased from 0.001 s ^−1 to 10 s ^−1 at 400 °C. However, the effect of chromium content on the maximum flow stress of steels did not exceed 50 MPa at tested temperatures and strain rates. Dynamic recrystallization (DRX) was observed for all tested steels at 1100 °C. Higher temperatures and lower strain rates seemed to promote DRX. The true strain required for DRX was the largest when the chromium content in steels was 1.53 wt.%. It delayed the occurrence of DRX.

Additively manufactured (AM) metallic parts exhibit substantially different microstructures compared to those that are conventionally produced. Characterization studies have revealed that the microstructure of as-built AM metallic materials is highly heterogeneous in many respects. The strongly anisotropic mechanical response under plastic deformation observed in AM metals, compared to their conventionally manufactured counterparts, lies in the aforementioned inherent microstructural disparities. In this study, we have focused on a high-manganese steel (HMnS) processed by laser powder bed fusion (LPBF), which exhibits twinning-induced plasticity (TWIP). The as-built microstructure is carefully characterized by electron backscatter diffraction (EBSD), transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. To unfold the potential of metal additive manufacturing, it is essential to understand the microstructure of AM products and its connection with the mechanical properties by means of numerical modeling and simulation. The mechanical response of AM components under plastic deformation is highly complex and its simulation requires advanced modeling and numerical methods. In the present study, in order to simulate the anisotropic plasticity of the LPBF-HMnS, we used the full field method for computational polycrystal homogenization combined with physics-based crystal plasticity constitutive and statistical microstructure modeling. The impact of different process-induced microstructural heterogeneity characteristics on macroscopic strain hardening behavior of the material has been comprehensively and systematically investigated. Finally, it has been argued why the chosen AM material with the selected processing parameters and chemical composition represented an ideal candidate for a generic assessment of the anisotropic polycrystal plasticity due to microstructural heterogeneity. Image, graphical abstract [ABSTRACT FROM AUTHOR]

This work investigates the susceptibility of high-interstitial CrMn austenitic stainless steel CN0.96 to hydrogen environment embrittlement. In this context, an N-free model alloy of CN0.96 steel was designed, produced, and characterized. Both steels were subjected to tensile tests in air and in a high-pressure hydrogen gas atmosphere. Both steels undergo severe hydrogen embrittlement. The CN0.96 steel shows trans- and intergranular failure in hydrogen, whereas the N-free model alloy shows exclusively intergranular failure. The different failure modes could be related to different deformation modes that are induced by the presence or absence of N, respectively. In the CN0.96 steel, N promotes planar dislocation slip. Due to the absence of N in the model alloy, localized slip is less pronounced and mechanical twinning is a more preferred deformation mechanism. The embrittlement of the model alloy could therefore be related to mechanisms that are known from hydrogen embrittlement of twinning-induced plasticity steels. • Hydrogen environment embrittlement of high-interstitial austenitic stainless steel. • Tensile testing of CrMnC steel with and without N in hydrogen gas. • Influence of N on the deformation and fracture behavior in hydrogen gas. [ABSTRACT FROM AUTHOR]

In this work, (Fe, Cr) 2 B, TiC and TiB 2 were respectively introduced to the high-Manganese heat-resistant steel by in situ solidification method. It shows that the second-phase particles can be selectively oxidized prior to the steel matrix during the initial stage of oxidation, which promotes the formation of a dense Cr 2 O 3 scale and inhibit the occurrence of internal oxidation as well as the formation of nodule oxide. A novel mechanism, so-called "reactive particle effect" was proposed to illustrate the beneficial effects resulting from the second-phase particles. • Three types of particles were respectively introduced into a high-manganese steel. • Severe internal oxidation occurs in the particle-free high-manganese steel. • Internal oxidation is eliminated in all particle-contained steels. • A new anti-oxidation mechanism, "reactive particle effect", is proposed. [ABSTRACT FROM AUTHOR]

Due to pronounced work-hardening induced by the complex interplay of deformation mechanisms such as dislocation slip, twinning and/or martensitic phase transformation, high-manganese steels represent a class of materials well-suited for mechanical surface treatment. In the present study, the fatigue behavior of a high-mangsanese steel showing twinning-induced plasticity (TWIP) effect at room temperature (RT) was investigated after deep rolling at 550 °C. Results are compared to a former study discussing the behavior after RT deep rolling. Evolution of the near-surface microstructure was analyzed by scanning electron microscopy (SEM), microhardness measurements and residual stress depth profiles obtained by X-ray diffraction (XRD). Both uniaxial tensile tests and uniaxial tension-compression fatigue tests have been conducted in order to rationalize the macroscopic material behavior. Following deep rolling at 550 °C, SEM measurements employing electron backscatter diffraction (EBSD) revealed a heavily deformed surface layer as well as localized deformation twinning. Specimens showed inferior hardness and residual stress depth profiles when compared to RT deep rolled counterparts. Tensile tests indicated no difference between the conditions considered. Fatigue properties however were improved. Such behavior is rationalized by a more stable residual stress state induced by dynamic strain aging.

The research presented in this paper is part of a larger project concerning deformation behavior, microstructure and mechanical properties of high-manganese steels with different chemical compositions and processed under various conditions. The current investigation deals with the development of microstructure and crystallographic texture of Fe-21.2Mn-2.73Al-2.99Si steel deformed in tension until fracture at ambient temperature. The deformation process of the examined steel turned out to be complex and included not only dislocation slip and twinning but also strain induced phase transformations (γ → ε) and (γ → α′). The formation of ε-martensite with hexagonal structure was observed within the microstructure of the steel starting from the range of lower strains. With increasing deformation degree, the α′-martensite showing a cubic structure gradually began to form. Attempts have been made to explain the circumstances or conditions for the occurrence of the deformation mechanisms mentioned above and their impact on the mechanical properties. The obtained results indicate that the strength and plastic properties of the steel substantially exceed those of plain carbon steels. Since both, mechanical twinning and the strain-induced phase transformations took place during deformation, it seems that both types of deformation mechanisms contributed to an increase in the mechanical properties of the examined manganese steel.

The impact of grain size on the work-hardening rate of two high-manganese steels with nearly identical stacking fault energy values of approximately 16.6 mJ m−2 (X60Mn17 alloy) and 16.5 mJ m−2 (X30MnAl17-1 alloy) was analyzed via macro-texture and micro-texture measurements as well as quasistatic tensile tests and phase analysis. Both alloys exhibited differences in twin volume fraction and volume fraction of the martensitic phase. The twin volume fraction increased with grain size. The X30MnAl17-1 alloy with Al and lower C content showed a lower overall twin volume fraction than the X60Mn17 alloy without Al. Additionally, the phase fractions of ε-martensite and α′-martensite were very low in the X30MnAl17-1 alloy. The increased grain size and the subsequent increase in twin volume fraction led to a relative decrease of the volume fraction of grains with <111>-orientation parallel to the tensile axis for both alloys. [ABSTRACT FROM AUTHOR]

Diffuse ultrasound is highly sensitive to changes in mechanical properties. Based on the coda wave interferometry analysis, we investigate the environmental temperature-induced wave velocity variations in high-manganese steels with plastic deformations by diffuse ultrasound. We observe the velocity changes in the materials at test with ~ 10 − 6 relative resolution. We propose the temperature-dependent coefficient as the key parameter for damage assessment in the specimens with different plastic deformations. The results show that the early-stage damage caused by plastic deformation in the specimens at test varying from 6% to 14% are successfully characterized by temperature-dependent coefficients in the absence of external mechanical load. The theoretical analysis on the sensitivity of the temperature-dependent coefficient to plastic deformation as well as the potential on-site application is discussed in this article. [ABSTRACT FROM AUTHOR]