A Review of Influencing Factors of Damping Properties of High Manganese Steel

High manganese steel has wide prospects in industry due to their excellent mechanical and damping properties. The quenching structures of high manganese steel are ε-martensite, γ-austenite and α'-martensite. Researches show that the damping properties of high manganese steel are related to these microstructures. Besides, there are many ways to improve the damping property of damping alloys. This paper reviews the damping mechanism and the influences of the ad-dition of alloying elements, heat treatment, pre-deformation and other factors on their damping performance, hoping to provide methods and ideas for the study of damping properties of high manganese steel. .

WELDING BETWEEN HIGH MANGANESE STEEL AND HIGH CARBON STEEL

Manuscript received 30 July 1999 Abstract The shielded metal arc welding (SMAW) of a manganese steel part as a crossing of railway track to a carbon steel part as the rails of the railroad is the welding of dissimilar steel. It are was known that it is not possible to the the rail of railroad directly to the cross- ing of railway track made from a steel containing about 14% of manganese (wt. ) because of so many differences between the two kinds of steels such as composition, microstructure,mechanical properties and weldability.A method was used to solve the problem by presetting an intermediate layer on each side of the joint and other special procedures were used.The result of test indicated that a good weld joint was obtained.

NUMERICAL SIMULATION OF TEMPERATURE FIELD ON FLASH BUTT WELDING FOR HIGH MANGANESE STEELS

An axial symmetry finite element model coupled with electricity-thermal effect was developed to study the temperature field distribution in process of the flash butt welding （FBW） of frog highmanganese steel. The influence of temperature dependent material properties and the contact resistance were taken into account in FEM ＇simulation. Meanwhile, the lost materials due to .splutter was resolved by using birth and death element. The result of analyzing data shows that the moddel in the FBW flashing is reasonable and feasible, and can exactly simulate the temperature field distribution. The modeling provides reference for analysis of welding technologies on the temperature field of high-manganese steel in FBW.

Influence of Impact Energy on Impact Corrosion-abrasion of High Manganese Steel

The impact corrosion-abrasion properties and mechanism of high manganese steel were investigated under different impact energies. The result shows that the wearability of the steel decreases with the increase of the impact energy. The dominant failure mechanism at a lower impact energy is the rupture of extrusion edge along root and a slight shallow-layer spalling. It transforms to shallow-layer fatigue flaking along with serious corrosion-abrasion when the impact energy is increased, and finally changes to bulk flaking of hardened laver caused by deeo work-hardening and heaw corrosion-abrasion.

Effect of Nb on Microstructure and Mechanical Properties in Non-magnetic High Manganese Steel

Microstructure and mechanical properties of two kinds of non-magnetic high manganese steels with and without Nb addition which experienced the same rolling and heating treatment were investigated by means of scan ning electron microscopy, electron back-scattered diffraction, transmission electron microscopy, X-ray diffraction and tensile test. It was found that the microstructure of the high manganese steel was refined by the Nb addition. Moreover, steel with Nb addition has a higher stacking fault energy which favors the deformation twinning, Twin ning is the most important deformation mechanism in the Nb-bearing steel. Therefore, steel with Nb addition has much higher strength and higher plasticity. The product of tensile strength and total elongation exceeds 61.8 GPa ·%. In addition, steel with Nb addition also has excellent non magnetic property.

Microstructure and Impact Wear Resistance of TiN Reinforced High Manganese Steel Matrix

A high-manganese austenitic steel matrix （Mn13） composite reinforced with TiN ceramic particles was synthesized by means of Vacuum-Evaporation Pattern Casting （V-EPC）. The composite microstructure and interface bonding of TiN/matrix were analyzed utilizing optical microscope （OM） and X-ray diffraction （XRD）. The effects of different volume fraction of TiN on impact wear resistance were evaluated by MLD-10 impact wear test. The results showed that TiN was evenly distributed in composite layer and had a good interface bonding with matrix when the volume fractions of TiN were 27% and 36% respectively. However, cast defects and TiN agglomeration occurred when the TiN volume fraction increased to 48~. Compared with high-manganese austenitic steel （Mnl3）, the im- pact wear resistance of the TiN-reinforced composite is better. In small impact load conditions, composite layer can effectively resist abrasives wear and TiN particles played an important role in determining impact wear resistance of composite layer. In large impact load, the synergistic roles of spalling of TiN particles and the increase of work hardening of Mn13 based material are responsible for impact wear resistance.

Evolution of Al2O3 inclusions by cerium treatment in low carbon high manganese steel

The influence of cerium（Ce）treatment on the morphologies,size and distributions of Al_2O_3 inclusions in low carbon high manganese steel was investigated by OM,SEM-EDS and theoretical calculation.The results showed that Ce can modify the morphologies and types of Al_2O_3 inclusions.After Ce treatment,the irregular Al_2O_3 inclusions were replaced by smaller and dispersive spherical cerium oxysulfides.The effects of treatment time and Ce content on the evolution of Al_2O_3 inclusions were examined.It indicated that Al_2O_3 inclusions were wrapped by rare earth inclusions to form a ring like shape Ce-enriched band around the inclusions.Model was established to elucidate the evolution mechanism of Al_2O_3 inclusions.Evolution kinetics of inclusions was discussed qualitatively to analyze the velocity controlled step.It was found that diffusion of Ce^（3＋）and Al^（3＋）in solid inclusion core and the formed intermediate layer would be the limited step during the evolution process.

Rietveld refinement, microstructure and high-temperature oxidation characteristics of low-density high manganese steels

Three forged low-density high manganese steels Mn28Al10,Mn28Al8 and Mn20Al10 were used as experimental materials in this study.The forged microstructure and external oxidation characteristics at 1323 K and 1373 K for 5-25 h in air were investigated by microstructural observation and X-ray diffraction（XRD）technique.The phase compositions and abundance in the forged and oxidized samples were quantitatively obtained by Rietveld method on the basis of XRD pattern analysis.The results showed that an austenitic microstructure formed in steels Mn28Al10 and Mn28Al8,and 18.02 wt%ferrite could be found in Mn20Al10.The relative amount of ~5.28 wt%-carbide（Fe_3AlC_（0.5））in Mn28Al10 was far greater than that in Mn28Al8 and Mn20Al10.The oxidation kinetics of forged steels oxidized at 1323 K for 5-25 h had two-stage parabolic rate laws;and the oxidation rate of the first stage was lower than that of the second stage.When they were oxidized at 1373 K for 5-25 h,the oxidation kinetics followed only a parabolic law and the oxidation rates were respectively greater than those at 1323 K for 5-25 h.When they were oxidized at 1323 K for 25 h,detached external scales contained Fe_2MnO_4and-Fe_2O_3oxides.-Al_2O_3and（Fe,Mn）_2O_3oxides could only be indexed in steels Mn28Al8 and Mn28Al10,respectively.When they were oxidized at 1373 K for 25 h,Fe_2MnO_4,Fe_3O_4,-Fe_2O_3 and-Al_2O_3oxides could all be indexed in the external detached scales.The main phase of detached external scales was Fe_2MnO_4;and the relative amount of-Al_2O_3in steel Mn28Al8 was higher than that in steels Mn28Al10 and Mn20Al.The external oxidation layers of these three forged steels oxidized at 1323 K and 1373 K for 25 h were essentially followed the sequence of-Al_2O_3,Fe_2MnO_4,Fe_3O_4,FeMnO_3,and Fe_2O_3from the substrate to the outside surface.The forged Mn28Al10 steel with austenitic microstructure and a certain amount of-carbide（~5.28 wt%in the present work）possessed a better combination of strength,ductility,specific strength,and oxidation rate when compared to that of the forged Mn28Al8 and Mn20Al10 steels.

On the transformation textures influenced by deformation in electrical steels,high manganese steels and pure titanium sheets

Transformation texture is normally different to deformation and recrystallization textures,thus influencing materials properties differently.As deformation and recrystallization are often inseparable to transformation in materials which shows a variety in types such as diffusional or non-diffusional transformations,different phenomena or rules of strengthening transformation textures occur.This paper summarizes the complicated phenomena and rules by comparison of a lot of authors’published and unpublished data collected from mainly electrical steels,high manganese steels and pure titanium sheets.Three kinds of influencing deformation are identified,namely the dynamic transformation with concurrent deformation and transformation,the transformation preceded by deformation and recrystallization and the surface effect induced transformation,and the textures related with them develop in different mechanisms.It is stressed that surface effect induced transformation is particularly effective to enhance transformation texture.It is also shown that the materials properties are also improved by controlled transformation textures,in particular in electrical steels.It is hoped that these phenomena and processing techniques are beneficial to the establishment of transformation texture theory and property improvement in practice.

Analysis of Solidification of High Manganese Steels Using Improved Differential Thermal Analysis Method

High manganese steels can damage the differential thermal analysis （DTA） instrument due to the manganese evaporation during high temperature experiments. After analyzing the relationship between residual oxygen and manganese evaporation, tanta- lum metal was employed to modify the crucible of DTA, and zirconium getter together with strict gas purification measures were applied to control the volatilization of manganese. By these modifications, problems of thermocouple damage and DTA instrument contamination were successfully resolved. Cobalt samples were adopted to calibrate the accuracy of DTA instruments under the same trial condition of high manganese steel samples, and the detection error was confirmed to be less than 1 ℃. Liquidus and soli- dus temperatures of high Mn steels were measured by improved DTA method. It was found that the liquidus temperatures of sam- ples tested by experiments increased linearly with the heating rates. To eliminate the effects of the heating rate, equilibrium liquidus temperature was determined by fitting the liquidus temperatures at different heating rates, and referred as real liquidus temperature. No clear relationship between solidus temperatures and heating rates was found, and the solidus temperature was finally set as the average value of several experimental data.

Hot workability of high manganese transformation induced plasticity steel

The hot deformation behavior and microstructure evolution of high manganese transformation induced plasticity steel(Fe - 20Mn - 3Si - 3Al) were investigated by using hot compression test in a temperature range from 800℃to 1 050℃and strain rate ranging from 0.01 s^(-1) to 5.0 s^(-1).The effects of temperature,strain rate,and true strain on the flow behavior and microstructures of high manganese transformation induced plasticity steel were discussed.The results show that the dynamic recrystallization occurs only at higher temperature and lower strain rate.Hot deformation behaviors of high manganese transformation induced plasticity steel were sensitive to temperature and strain rate.The apparent stress exponent and the apparent activation energy of the investigated steel were about 4.280 and 463.791 kJ/mol, respectively.The apparent activation energy of the high manganese transformation induced plasticity steel was approached to the austenitic stainless steel(400 -500 kJ/mol).The hot working equation is obtained. Hot deformation peak stress increased with increasing of the value of lnZ.Peak stress and InZ exhibits a linear variation,the linear correlation coefficient was 0.988 9.The results show that the dynamic recrystallization was prone to occur when lnZ≤43.842 26 and Z≤1.098×10^(19),and better hot deformation properties would be obtained under this condition.

Hot deformation behavior and hot-metal-gas-forming process of V micro-alloyed high manganese steel

The hot deformation behavior of a newly designed V micro-alloyed high manganese steel(HMnS)was investigated in order to guide the development of the hot-metal-gas-forming process.Single-pass hot compression experiments were conducted in the temperature range of 950–1100°C and the strain rate range of 0.05–10 s^(−1),and the stress–strain curves and the corresponding softening mechanism of the V micro-alloyed HMnS were analyzed.Results show that two types of stress–strain curves,representing the work hardening(WH)-dynamic recovery(DRV)-dynamic recrystallization(DRX)mechanism and the WH–DRV mechanism,respectively,occur during the deformation process.Moreover,the WH–DRV–DRX mechanism gradually transforms into the WH–DRV mechanism with the increasing strain rate and decreasing deformation temperature.Two types of constitutive models considering the softening mechanism difference were established and verified by additional hot-deformation experiments.Hot processing map of the HMnS was established and correlated well with the microstructure evolution result.Based on the constitutive models and processing map,the optimal processing parameter range and flow stress of HMnS for the hot-metal-gas-forming were determined.

Effect of Al content on the reaction between Fe-10Mn-xAl(x=0.035wt%,0.5wt%,1wt%,and 2wt%)steel and CaO-SiO_(2)-Al_(2)O_(3)-MgO slag

The effect of Al content(0.035 wt%,0.5 wt%,1 wt%,and 2 wt%)on the composition change of steel and slag as well as inclusion transformation of high manganese steel after it has equilibrated with Ca O-Si O_(2)-Al_(2)O_(3)-Mg O slag was studied using the method of slag/steel reaction.The experimental results showed that as the initial content of Al increased from 0.035 wt%to 2 wt%,Al gradually replaced Mn to react with Si O_(2)in slag to avoid the loss of Mn due to the reaction;this process caused both Al_(2)O_(3)in slag and Si in steel to increase while Si O_(2)and Mn O in slag to reduce.In addition,the type of inclusions also evolved as the initial Al content increased.The evolution route of inclusions was Mn O→Mn O-Al_(2)O_(3)-Mg O→Mg O→Mn O-Ca O-Al_(2)O_(3)-Mg O and Mn O-Ca O-Mg O.The shape of inclusions evolved from spherical to irregular,became faceted,and finally transformed to spherical.The average size of inclusions presented a trend that was increasing first and then decreasing.The transformation mechanism of inclusions was explored.As the initial content of Al increased,Mg and Ca were reduced from top slag into molten steel in sequence,which consequently caused the transformation of inclusions.

Casting properties of ASTM A128 Gr.E1 steel modified with Mn-alloying and titanium ladle treatment

This work aims to produce a high manganese steel with more refined austenite grains and better wear resistance without sacrificing the toughness and tensile properties by Mn alloying and Ti ladle treatment in comparision to ASTM A128 Gr.E1 steel (1.0C-13Mn) that is mostly used in the mining industry.The 1.0C-17Mn-xTi alloys (x=0,0.05 and 0.1,in wt.%) were prepared.A relationship was established between the microstructures and mechanical properties of the as-cast and solution annealed alloys.Increasing Ti content increases the stable Ti(CN) phase on and beside the grain boundaries and decreases up to 37% the austenite grain size of the as-cast alloy with 0.10wt.% Ti.Correspondingly,after solution annealed,optimized titanium content (0.05wt.%) results in significant improvements in wear resistance,hardness,elongation,yield and tensile strengths by 44%,31%,30%,8% and 12%,respectively,except 9% decrease in impact toughness compared to ASTM A 128 Gr.E1 steel without modification.These results show that 1.0C-17Mn-0.05Ti alloy can be used for parts exposed to high load wear and applied in conditions where relatively high tensile properties with sufficent ductility is needed.

Influence of welding parameters on nitrogen content in welding metal of 32Mn-7Cr-1Mo-0.3N austenitic steel

The transfer behavior of nitrogen into the welding metal during gas tungsten arc welding process of 32Mn-7Cr-1Mo-0.3N steel was investigated. The effects of gas tungsten arc welding process variables, such as the volume fraction of nitrogen in shielding gas, arc holding time and arc current on the nitrogen content in the welding metal were also evaluated. The results show that the volume fraction of nitrogen in gas mixture plays a major role in controlling the nitrogen content in the welding metal. It seems that there exhibits a maximum nitrogen content (depending) on the arc current and arc holding time. The optimum volume fraction of nitrogen in shielding gas is 4% or so. The role of gas tungsten arc welding processing parameters in controlling the transfer of nitrogen is further (confirmed) by the experimental results of gas tungsten arc welding process with feeding metal.

Characterization of Tensile Strain Hardening Behaviors for 32Mn-7Cr-1Mo-0.3N Cryogenic Austenitic Steel

The strain hardening behaviors of 32Mn-TCr-1Mo-0.3N austenitic steel were characterized by a simple and effective method. The results show that Hollomon relationship is not applicable during total uniform deformation stage. The flow equation was proposed, Inσ=αexp（lnε/b）＋c. The variation rates of strain hardening exponents with true strain at 77 K are obviously higher than that at other temperatures and the value of d^2σ/dε^2 becomes positive during high strain stage. The characters of this variation are principal reasons for increasing elongation at 77 K. The forming of mechanical twin as well as ε-martensite leads to a high elongation at 77 K.

Wear Resistance of Austenitic Steel Fe–17Mn–6Si–0.3C with High Silicon and High Manganese

To solve the problem of poor wear resistance in conventional Hadfield steels under medium and low stress, a new kind of steel with high silicon and high manganese Fe-17Mn-6Si-0.3C was designed and its wear resistance was studied. The results showed that it exhibited better wear resistance than conventional Hadfield steel in both dry friction and abrasive friction. The better wear resistance of the new steel with high silicon and high manganese resulted from the stressinduced γ→ε martensitic transformation.

Influences of Thermal Martensites and Grain Orientations on Strain-induced Martensites in High Manganese TRIP/TWIP Steels

Strain-induced martensites in high manganese TRIP/TWIP steels were investigated in the presence of thermal martensites and under the influence of austenitic grain orientation by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and electron backscattered diffraction （EBSD）. Before deformation, the morphology of α＇- M depended mainly on the number of variants and growing period. Regardless of martensite morphologies and deformation, the Kurdjumov-Sachs （K-S） orientation relationships always maintained. The 6 α＇-M variants formed from a plate of ε-M were of 3 pairs of twins with a common axis 〈110〉α＇ parallel to the normal of {112}γ habit plane to minimize transformation strain. When α＇-M could be formed only by deformation, it nucleated at the intersection of ε-M variants and grew mainly in thick ε-M plates. Thick ε plates promoted significantly the α＇-M and weakened the influence of grain orientations. During tension, the transformation in 〈100〉-oriented grains was observed to be slower than that in 〈121〉-oriented grains. Deformation twins promoted ε-M formation slightly and had no apparent effect on α＇-M. Deformation increased the number of ε-M variants, but reduced that of α＇-M variants.

Dependence of Deformation Twinning on Grain Orientation and Texture Evolution of High Manganese TWIP Steels at Different Deformation Temperatures

Mechanical properties, microstructure and texture evolution were studied in two tensile-deformed high manganese TWIP steels at different temperatures. Special attention was paid to the effects of deformation tempera- ture and grain orientation on twinning behavior. The results showed that, at --70 ℃ and at room temperature, both twins and hexagonal martensite were found in a lower manganese steel of 26Mn. With deformation temperature ris- ing, twins became less and they disappeared at 500 ℃. Strong 〈111〉 texture appeared at 300 ℃, while it weakened at 500 ℃ due to the low strain rate and higher stacking fault energy. EBSD measurement revealed the dependence of deformation twinning on grain orientation at all test temperatures.

Microstructure and Mechanical Properties of High Manganese TRIP Steel

Microstructure evolution and mechanical properties of newly designed 0.1C-6Mn-0.5Si-1Al TRIP-aided steels under different annealing conditions and the effects of matrix microstructure before intercritical annealing on the final microstructure were studied by means of X-ray diffraction（XRD）,scanning electron microcopy（SEM）,dilatometric simulation,optical microstructure（OM） and tensile testing in this work.The experimental results indicate that the TRIP steel with Mn of 6% could form a considerable amount of retained austenite with good TRIP effect after a simple intercritical annealing treatment,and the matrix microstructure before intercritical annealing treatment can greatly affect the final microstructure.The original microstructure of the ferritic matrix steel was eliminated,while annealed martensite was remained from the martensite matrix steel under the same intercritical annealing conditions