High Manganese Austenitic Steel Research Articles

Effect of thermo-mechanical processing on the low impact abrasion and low stress sliding wear resistance of austenitic high manganese steels

The low impact abrasion and low stress sliding wear properties of two thermo-mechanically processed austenitic high manganese steels (Fe17Mn and Fe17Mn3Al) have been studied. It is observed that the application of thermo-mechanical processing (TMP) can significantly improve the low impact abrasion and low stress sliding wear resistance of both the steels. Thermo-mechanically processed Fe17Mn steel shows higher impact abrasion and sliding wear resistance compared to the thermo-mechanically processed Fe17Mn3Al steel. For both the steels, the impact abrasion wear mechanisms are cutting and spalling. However, in the case of low stress sliding wear, an oxidation type of wear is observed.

Engineering Method for Analysis of the Ability to Strain-Hardening of Steels

A study of the structure and strain-hardening ability relationship was carried out in this work for wear-resistant steels of two structural classes: high-manganese austenitic steel 110G13L and metastable austenitic chromium-manganese steel 60G9KhL. It is shown that the strain-hardening ability can be estimated using a methodologically simple engineering criterion. The criterion determines the metal tendency to harden by determining the Rockwell hardness at the bottom of the indentation cup of the Brinell press indenter

Grain Size-Dependent Mechanical Properties of a High-Manganese Austenitic Steel

The effect of grain size on the mechanical properties of a high-manganese (Mn) austenitic steel was investigated via electron-backscattered diffraction, transmission electron microscope, X-ray diffraction, and tensile and impact tests at 25 °C and − 196 °C. The Hall–Petch strengthening coefficients for the yield strength of the high-Mn austenitic steels were 7.08 MPa mm0.5 at 25 °C, which increased to 14 MPa mm0.5 at − 196 °C. The effect that the grain boundary strengthening had on improving the yield strength at − 196 °C was better than that at 25 °C. The impact absorbed energies and the tensile elongations were enhanced with the increased grain size at 25 °C, while they remained nearly unchanged at − 196 °C. The unchanged impact absorbed energies and the tensile elongations were primarily attributed to the emergence of the micro-twin at − 196 °C, which promoted the cleavage fracture in the steels with large-sized grains. Refining the grain size could improve the strength of the high-Mn austenitic steels without impairing their ductility and toughness at low temperature.

AN ANALYSYS OF WEAR AND MECHANICAL AND TRIBOLOGICAL PROPERTIES OF HIGH-MANGANESE CAST STEEL HARDENED BY DIFFERENT METHODS

Properties of high manganese austenitic cast steel are not satisfactory; therefore, this material should be hardened. Currently, the commonly used method of hardening does not allow eliminating problems related to premature wear of railway frogs. Therefore, many studies have been carried out to find an alternative method to obtain improved wear resistance of such elements. The article presents an analysis of the mechanical and tribological properties of base and hardened, by different methods, high-manganese cast steel applied for turnouts. Tests were performed for three hardening methods: explosive, pressure-rolling, and dynamic impact. The results were compared with the properties of base material after saturation treatment. The conducted tests allowed the determination of hardness profiles of hardened surfaces, as well as the wear resistance and coefficient of friction, and the obtained results are very promising. Hardening by dynamic impact provided much better results in relation to presently used explosive hardening technology.

Effect of Aluminum on the Structural Transitions and the Wear Resistance of Hadfield Steel under Friction

The structural transitions and tribological properties of carbon-containing high-manganese aluminum-doped austenitic steels tested under different dry-conditions of sliding friction have been considered. The methods used for the structural study of steels are metallography, X-ray diffraction analysis, and transmission electron microscopy. It has been shown that the doping of the studied steels with aluminum taken in the amount of 1.2 wt % significantly increases their resistance to abrasive wear, and especially adhesive wear (up to 20 times). It has been hypothesized that the observed positive effect of aluminum on the wear resistance of austenitic steels is due to the activation of the planar dislocation sliding mechanism, which increases the dispersion of nanocrystals and, correspondingly, the hardness of the surface layer of steels under the conditions of nanostructuring rotational strain by means of friction.

Nanotwin Formation in High-Manganese Austenitic Steels Under Explosive Shock Loading

The micro-deformation mechanisms active in a high-manganese austenitic steel were investigated upon explosive shock loading. Single system of nanotwins forming within primary twins were shown to govern the deformation despite the elevated temperatures attained during testing. The benefits of nanotwin formation for potential armor materials were demonstrated.

Ab Initio-Based Modelling of the Yield Strength in High-Manganese Steels

An ab initio-based model for the strength increase by short-range ordering of C-Mn-Al clusters has been developed. The model is based on ab initio calculations of ordering energies. The impact of clusters on the yield strength of high-manganese austenitic steels (HMnS) is highly dependent on the configurational structure of the cells that carbon atoms will position themselves as interstitial atoms. The impact of the alloying elements C, Mn, and Al on the potential and actual increase in yield strength is analyzed. A model for the calculation of yield strengths of HMnS is derived that includes the impact of short-range ordering, grain size refinement, and solid solution strengthening. The model is in good agreement with experimental data and performs better than other models that do not include strengthening by short-range ordering.

ВЛИЯНИЕ ТЕРМИЧЕСКОЙ ОБРАБОТКИ НА СТРУКТУРУ И ИЗНОСОСТОЙКОСТЬ СТАЛЕЙ ПЕРЛИТНОГО КЛАССА

From the ecological point of view, high-manganese austenitic steels of 110G13L type are undesirable in the production because of the high emission of manganese oxides to the atmosphere while melting in the electric arc furnaces, gas-oxygen cutting, and welding operations. Another disadvantage of steels of this class is their low initial hardness, which causes the revet closing capacity of the working parts of castings under the conditions of dynamic loads. Moreover, these steels are poorly machinable. The paper presents the results of the comparative study of the relationship between the structure formed in the process of heat treatment and the abrasive wear resistance of steels of two structural classes - high-manganese austenitic 110G13L steel and the 70H2GSML perlite-class steel. The wide use of 110G13L steel for the production of parts operating under the impact-abrasive wear and the repetitive contact-impact force is caused by the ability for high friction hardening of stable manganese austenite with low energy of packaging defects combined with the good impact strength. The disadvantages of 110G13L steel are the high quenching temperature, poor environmental performance and economic reasons that make it necessary in some cases to replace it with the perlite steels. The study of wear resistance of 70H2GSML perlite-class steel depending on the tempering temperature after normalization showed that this steel could be used for the casting of replaceable cast parts for crushing-milling equipment operating under the abrasive action without significant impact loads after normalization and high tempering. The wear resistance of samples made of 70H2GSML steel with the secondary sorbite structure, when testing steady abrasive, makes 55-60 % of level provided by samples of 110G13L steel, however, the lower cost, manufacturability and the environmental problems in some cases can settle the issue in favor of the application of perlite steel. The additional reserves to increase the wear resistance of 70H2GSML steel involve the quenching at high temperatures due to the formation of the structure of retained austenite that, in the process of abrasive wear, transforms into deformation martensite on the working surface increasing the steel’s friction hardening ability.

Effect of Titanium Addition on High Temperature Workability of High Manganese Austenitic Steel

This work was performed under the support from POSCO and the Human Resources Development program (No. 20154030200680) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Trade, Industry and Energy.

Quantum-mechanical analysis of effect of alloying elements on \u03b5-martensite start temperature of steels

With regard to the transformation mechanism of austenitic high manganese steel, the prediction of the ε-martensite start temperature is a critical consideration in alloy design. Evaluation of the ε-martensite start temperature makes it possible to predict the microstructure and to understand the phase transformation occurring during deformation. Here we use the quantum mechanical calculation of random alloys to understand the physics for ε-martensitic transformation in steels. We could find the linear relationship between the measured ε-martensite start temperatures and the crystal structure stability for various compositions. We also could estimate the effect of several alloying elements. It is expected that the effect of decreasing the temperatures for the same amount of alloying elements addition will be larger moving farther from Group VIII. By creating a free-energy model that reflects the temperature effect, we were able to calculate the average driving force required for the ε-martensitic transformations.

Tribo-corrosion study of nickel-free, high nitrogen and high manganese austenitic stainless steel

The electrochemical corrosion and tribo-corrosion behaviors of nickel-free high nitrogen (HN SS) and high manganese containing austenitic stainless steel were studied in simulated body fluids such as Ringer's and artificial saliva solutions (ASS) using tribo-meter attached with the potentiostat. Type 316L SS used as reference alloy for comparison. Open circuit potential (OCP) and potentiodynamic polarization techniques were used to examine the passivation and corrosion behavior of both the stainless steels under the applied loads of 5 and 10 N at room temperature and also compared with the static condition of corrosion. Pitting resistance of HN SS was found to be significantly higher over type 316L SS.

On the effect of deformation twinning and microstructure to strain hardening of high manganese austenitic steel 3D microstructure aggregates at large strains

The hardening and deformation characteristics of Hadfield microstructure are studied to investigate the effect of microstucture to the material behavior. A crystal plasticity model including dislocation slip and deformation twinning is employed. The role of deformation twinning to the overall strain hardening of the material is evaluated for two different grain structures. Large compressive strains are applied on 3D microstructural aggregates representing the uniform and non-uniform grain structures of Hadfield steels. The grain structure has an effect on the strain hardening rate as well as on the overall hardening capability of the microstructure. A major reason causing the difference in strain hardening arises from the different twin volume fraction evolution influenced by intra-grain and inter-grain interactions. A mixture of large and small grains was found to be more favorable for twinning and thus resulting in a greater hardening capability than uniform grain size.

Influence of the phase composition and microstructure of plasma cladding Fe-Cr-Ni-C alloy coating on residual stress and crack formation

The Fe–Cr–Ni–C alloy coatings with different phases have been prepared by plasma cladding technique on high manganese austenitic steel preheated with different temperatures. The effect of the phase composition on crack formation, residual stress, and micro-hardness of Fe–Cr–Ni–C alloy coatings was investigated by scanning electron microscopy (SEM) with energy-dispersive spectrum (EDS), micro-hardness tester, infrared thermal imager, and residual stress tester. The results show that for Fe-based coating deposited on the substrate non-preheated, the transverse and perpendicular cracks are generated after the end of cladding, which belongs to transcrystalline fracture. The Fe–Cr–Ni–C alloy coatings are composed of the solid solution of austenitic and fishbone-like eutectic carbide, which was mainly (Cr, Fe)7C3. As the preheating temperature of substrate is 350 °C, granular metallic carbides with the diameter 1 μm are precipitated at grain boundaries and no cracks formed. The carbide phases are mainly (Cr, Fe)7C3 and (Cr, Fe)23C6 in cladding coatings. With the decreased rate of cooling, carbide precipitation phase changed from metastable (Cr, Fe)7C3 to stable (Cr, Fe)23C6 phase. The precipitation stable carbide phase has significance to prevent the formation of cracks and improves the micro-hardness of the Fe-based coating on the substrate preheated to 350 °C. The residual stress of specimen with substrates of non-preheating and preheating 250 and 350 °C is 234.2, 267.3, and 300.6 MPa, respectively. The maximum value of micro-hardness of coating with substrates of non-preheating is 986.1 HV, which is about six times than that of substrate.

Prominence of Hadfield Steel in Mining and Minerals Industries: A Review

High manganese austenitic steel, popularly called “Hadfield steel” has dominated and played significant role in wear applications, especially in the mines and minerals industries since its invention over a century ago. A review on the researches on this steel revealed that its prominence in these fields is mainly due to its good combination of impact and abrasion wear resistance arising from its high toughness and high hardness respectively. Its strain hardening ability under impact loading is evidenced by increase in hardness as the material work hardens; this lowers the amount of wear in service. The work hardening property of the steel has been linked to governing mechanisms such as dislocation, deformation twinning, and dynamic strain ageing; also, it is enhanced by increase in carbon, ageing temperature and reduction in manganese content. Carbide precipitation along the grain boundaries and within the grains is the major cause of embrittlement of the steel. These carbides together with voids and porosities during casting solidification, improper heat treatment, overheating during welding, use of unsorted scrap metal and wrong wear application have been identified as the causes of premature failure in service. Hardfacing method has been proposed as a means of substituting the steel in wear applications, as alternative wear materials such as white cast iron and austempered ductile iron lack the combination of impact and abrasion resistance being offered by the Hadfield steel.

Effect of Aging Temperature on Microstructure and Properties of V Alloyed High Manganese Austenitic Steel

The effect of aging temperature on microstructure and mechanical properties of Fe-16Mn-1.3C-0.3V steel was investigated. After a series of heat treatment experimental processes, including solution treatment at 1080 oC for 1 h then aging treatment at 350 oC, 400 oC, 450 oC, 500 oC and 550 oC for 1 h respectively, the microstructure of V alloyed high manganese austenitic steels were studied using optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The experimental steel had the best comprehensive performance after aging treated at 450 oC for 1 h. It presented hardness of 249HB, impact toughness of 215 J·cm-2, tensile strength of 707 MPa, yield strength of 421 MPa and elongation of 30.8%. With the aging temperature increased, the amount of precipitates increased and precipitates gradually transformed from globularity to needle. EDS analysis showed the most striking difference between two types carbides. That the globular carbide had a lot of vanadium element, which could cause the hardness of globular carbide higher than needle-like carbide. TEM showed the size of these globular carbide particles were 10~100 nm. SADP demonstrated that the fine globular precipitate was vanadium carbide (VC).

Studies on the Mechanism of Work Hardening of Austenitic High Manganese Steel Alloyed with Chromium and Vanadium

This article studies the mechanism of work hardening of austenitic high manganese steel alloyed with chromium and vanadium. The steel was annealed at 650°C before austenitizing at 1100°C, and then was quenched with water. We have observed that after the heat treatment, the size of austenite grain was small (1,950μm2 - level 6). The hardness of the steel was 223HB and the toughness was 115J/cm2. After impact loading, there was no martensite but twinning and sliding in the microstructure of the steel. The nano austenite was found in the microstructure. The steel was also hardened by small austenite grain and the carbide particles were finely dispersed in the microstructure.

Metallurgical Nature of the As-Cast Microstructure of High-Nitrogen, High-Manganese Stainless Steels

Abstract High-nitrogen, high-manganese austenitic steels because of their non-magnetic behavior and corrosion resistance in combination with high strength and toughness serve various applications. The Schaeffler diagram is commonly used for predicting the as-cast microstructures but it does not reflect the nature of the austenite associated with the sequence of phase formation during solidification. Thermodynamic simulations are an aid to understanding the metallurgical nature of austenite. In this study, the microstructure was revealed by tint etching with examination using polarized light with the light optical microscope. The fragments of dendritic arms that share a common crystallographic orientation were identified by this technique. Two kinds of austenitic microstructures, both with grains formed by sharply defined primary and secondary dendritic arms and with grains having a blurred dendritic pattern, were observed. Solidification through austenite freezes the chemical inhomogeneity, whereas solidification through δ-ferrite, with subsequent transformation of δ-ferrite to austenite, leads to a “blurring” of the dendritic structure. These two kinds of microstructures were interpreted by a Schaeffler–Spiedel diagram which is modified in this paper. Electrochemical investigations showed that the chemical homogeneity of the austenite obtained by primary δ-ferrite solidification exhibited improved corrosion properties.

Mechanical Properties, Microstructure and Phase Composition of Thin Magnetron Sputtered TWIP Steel Foils

Abstract Some high manganese austenitic steels show extraordinarily high ductility due to twinning induced plasticity (TWIP). The TWIP-effect is based on the formation of crystal twins in the austenitic lattice structure as a response to mechanical strain resulting in an extraordinary high ductility. Therefore, TWIP steels are very interesting for forming processes like deep drawing. Within the collaborative research center 747 (SFB 747 “Mikrokaltumformung”) of the German Research Foundation (DFG), micro-components are produced by deep drawing from thin metal foils with thicknesses from 20 μm to 50 μm. The production of such foils by conventional methods as multiple rolling processes of cast sheets is very time consuming since the initial defect free crystal lattice has to be recovered repeatedly by heat treatments after each rolling process to reach a final foil thickness below 50 μm. In the present work, physical vapor deposition (PVD) by DC magnetron sputtering was used as an alternative way to produce thin (≈ 15 μm) TWIP steel foils. An iron based alloy with 25 mass % manganese, 3 mass % silicon and 3 mass % aluminum was deposited onto 100 μm copper foils. After the deposition process the copper substrate foils were removed by selective etching without affecting the resulting TWIP steel films. Microstructure, phase contents and mechanical properties of the resulting PVD-X5MnAlSi25-3-3 TWIP-steel foils were characterized as a function of post annealing conditions. Additionally, the influence of the roughness of the copper substrate foils on the mechanical properties of the resulting PVD-TWIP steel foils was investigated.

Evaluation of Formability Under Different Deformation Modes for TWIP900 Steel

Automotive manufacturers always seek high strength and high formability materials for automotive bodies. Advanced high strength steels (AHSS) are excellent candidates for this purpose. These steels generally show a reasonable degree of formability, in addition to their high strength. One particular type is the twinning-induced plasticity (TWIP) steel, which is a high manganese austenite steel, and represents a second generation in AHSS. In this study, comprehensive deformation analysis of TWIP900CR steel including tensile, bending, Erichsen, and deep drawing of cylindrical cups tests is made. Finite element simulation of U and V shaped bending processes is also performed. Results indicate that the TWIP steel has good mechanical properties and high formability. However, springback is quite significant. The coining force should be considered in order to reduce the amount of springback. For springback prediction, it is found that the Yld2000-2d material model has better prediction capability than the Hill48 model.

Effects of Gas Nitriding Temperature on the Surface Properties of a High Manganese TWIP Steel

The effects of gas nitriding temperature on the cross section morphology, element nitrogen distribution, and surface layer compositions of a cold rolled and pre-strained high manganese austenitic TWIP steel 25Mn-3Cr-3Al-0.3C-0.01N and the corresponding anti-corrosion ability have been studied. The results show that, depending on nitriding temperature, the distribution of element nitrogen and main phase compositions are significantly different in the nitriding layers. At a temperature lower than 500 °C, the main composition in the modified layer is S-phase and the nitrogen concentration linearly decreases from the surface to the center, while Fe4N forms with S-phase and a step-like distribution of nitrogen content is present at nitriding temperature of 600 °C. Caused by the increasing of modified layer thickness and the formation of S-phase and Fe4N, the surface hardness was obviously enhanced. Anodic polarization curves in 3.5 wt. % NaCl solution indicate that the nitrided processes have a tremendous modification effect on anti-corrosion ability. Moreover, the increase of (111) oriented grain, caused by the elevated nitriding temperature, has a positive effect on the corrosion resistance.