Cast High-manganese Steel Research Articles

Reaction Behavior at the Contact Interfaces between High-Manganese Cast Steel or High-Manganese Spheroidal Graphite Cast Iron and Molten Aluminum Alloys

Reaction Behavior at the Contact Interfaces between High-Manganese Cast Steel or High-Manganese Spheroidal Graphite Cast Iron and Molten Aluminum Alloys

Assessment of fatigue crack growth in metro cast manganese steel frogs and inspection strategy

Fatigue cracking is one of the notable failure mechanisms of railway turnout frogs due to high contact forces induced by the wheel-rail impact. However, the treatments specific to the frogs of cast high manganese steel to prevent sudden failure are rarely provided and are independent of the crack conditions, which can significantly affect the fatigue crack growth rate. To address this shortcoming, the fatigue crack growth in a cast high manganese steel frog is computationally investigated with varied wheel and crack conditions. The dynamic wheel-frog impact is first simulated to obtain the distribution of contact pressure imposed on the frog, and the propagation of the fatigue crack is then predicted using the finite element formulation in fracture mechanics. The simulation results show that the train speed and axle load can change the maximum contact stress. Nevertheless, when representing the growth rate in terms of the cumulative passing axle load, the effect of axle load and train speed on the crack growth is minimal and moderate, respectively. In contrast, the initial crack conditions, including the location and angle, have an overweighted influence. As a result, an inspection scheduling strategy for identified cracks with different conditions is proposed to consider both safety and operational efficiency.

Effect of Heat Treatment on Microstructure and Mechanical Properties of High-Carbon and High-Manganese Cast Steel Subjected to Bainitic Reaction

Effect of Heat Treatment on Microstructure and Mechanical Properties of High-Carbon and High-Manganese Cast Steel Subjected to Bainitic Reaction

Mechanical Property of New Cast High Manganese Steel and Its Application

Based on the traditional Mn13, the new cast high manganese steel was prepared by adding different Cr, Mo, B, and Re elements in the composition. Its microstructure, mechanical properties, and wear quantity of surface were investigated. Results show that after water toughening, the pearlite dissolved and a few linear carbides were kept at the boundary of grains in the microstructure. All of the hardness was more than 220 HB, impact toughness reached or exceeded 140 J/cm2, and ultimate tensile strength was 753 MPa. The lowest abrasive wear quantity was 0.02 g. The newly cast high manganese steel was applied to produce breaking teeth casting of the crusher. Velocity and temperature fields were simulated to predict some defects during the mold filling and solidification process with finite element software for 4 foundry processes. The optimal technological parameter was adapted to make breaking teeth components.

Effect of Surface Impacting Parameters on Wear Resistance of High Manganese Steel

High manganese steel has always been subjected to pre-hardening treatment before use owing to its low initial strength. Therefore, cast high manganese steel was pre-hardened in this work by surface impacting treatment under different parameters to evaluate its state. The microstructures, hardening characteristics, and wear resistances of the pre-hardened high manganese steel samples were all investigated. The results indicated that increasing the sample temperature, reducing the impact pin size, and increasing the impact times on a single-point can enhance the surface hardening effect to different degrees. Dislocations and deformation twins were produced on the top surface and within a certain depth of test steel under different impacting conditions. The optimal hardening effect of test steel was achieved at a temperature of 300 °C, a pin size of 10 × 10 mm2, and 9 impacts on a single point. The surface hardness of the treated sample reached 542 HV. For friction and wear testing, the best wear resistance was achieved at a temperature of 300 °C, a pin size of 10 × 10 mm2, and 3 impacts on a single point with a surface hardness of 446 HV. Further enhancement in impact hardening effect resulted in microcracking along the surface of test steel. In turn, the induced embrittlement led to the poor wear resistance.

The wear mechanism of mill beaters for coal grinding made-up from high manganese cast steel

Determination of the cause-and-effect relationship regarding the wear of the lining (beater) of a coal beater mill is presented. The type and state of the material used for the aforementioned mill element was assessed. The lining wear mechanism was brought to the state of the aforementioned material. In the analyzed case, excessive wear of the Hadfield steel beater of the fan mill was identified. This study analyzes the chemical composition, macro- and microscopic examinations and hardness tests to find the cause of their unsatisfactory wear resistance. The test results show a significant influence of the carbon content on the process of strengthening the surface layer of the beater and the justification for considering the use of various materials for individual elements of the beaters. The methodology of testing the material's ability to deformation hardening was proposed and the role of the manganese cementite mesh in the decohesion (destruction) of the structure as a result of the coincidence of such precipitates with intense deformation micro-twinning has been presented. Analyzed cast steel has a high tendency to strain hardening (from 190 HBW to 500 HBW). As a result of exploitation, investigated plates were highly worn. The primary mechanism of wear was erosion. The presence of carbides in the microstructure also indicates an incomplete supersaturation of the material.

Changes in Microstructure and Abrasion Resistance during Miller Test of Hadfield High-Manganese Cast Steel after the Formation of Vanadium Carbides in Alloy Matrix.

Hadfield cast steel is characterized by high wear resistance, but this is only when it is subjected to the effect of dynamic loads. During unloaded abrasion, e.g., sand abrasion, its wear resistance is very low and comparable to the wear of carbon cast steel. To increase the wear resistance of this alloy for operation under the conditions of low pressure or low stress, primary vanadium carbides were produced by the metallurgical process to obtain a two-phase structure after alloy solidification. Compared to samples made of Hadfield cast steel, the primary, very hard carbides, evenly distributed in an austenitic or austenitic-martensitic matrix, increase (at least three times) the wear resistance of samples tested in an abrasive mixture of silicon carbide and water. The changes in microstructure and hardness obtained in alloys after heat treatment (quenching at 1000–1150 °C in water and tempering at 600 °C) are presented. The bulk hardness of the matrix ranged from 370 HV to 660 HV. After heat treatment, the secondary, dispersed vanadium carbides, precipitated in the alloy matrix.

Effect of SiZr Modification on the Microstructure and Properties of High Manganese Cast Steel

Effect of SiZr Modification on the Microstructure and Properties of High Manganese Cast Steel

Changes in Abrasive Wear Resistance during Miller Test of High-Manganese Cast Steel with Niobium Carbides Formed in the Alloy Matrix

High-manganese Hadfield cast steel is commonly used for machine components operating under dynamic load conditions. The high fracture toughness and abrasive wear resistance of this steel are the result of an austenitic structure, which—while being ductile—at the same time tends to surface harden under the effect of cold work. Absence of dynamic loads (e.g., in the case of sand abrasion) causes rapid and premature wear of parts. To improve the abrasive wear resistance of high-manganese cast steel for operation under the conditions free from dynamic loads, primary niobium carbides are produced in this cast steel during the melting process to obtain in castings, after melt solidification, the microstructure consisting of an austenitic matrix and primary niobium carbides uniformly distributed in this matrix. The measured hardness of the tested samples as cast and after solution heat treatment is 260–290 HV and is about 30–60 HV higher than the hardness of common Hadfield cast steel, which is 230 HV. Compared to common Hadfield cast steel, the abrasive wear resistance of the tested high-manganese cast steel measured in the Miller test is at least three times higher at the niobium content of 3.5 wt%. Increasing the niobium content to 4.5 wt%. in the tested samples increases this wear resistance even more.

Modification of High-Manganese Steel Castings with Titanium Carbonitride

Modification of high-manganese steel castings in the mold by titanium carbonitride is investigated. First, the basic principles of alloying and modification of cast alloys are outlined, and the relevant literature is reviewed. That provides the basis for formulating the research goals. The practical significance of the research for casting enterprises is confirmed. Next, the materials employed are considered in detail: the batch components, the modifier, the materials used in the casting molds. Likewise, the experimental methods are described: in particular, the methods used in producing experimental castings and in determining the thermal conditions in the mold and the optimal heat treatment. In addition, the metallographic techniques employed are noted. The experimental results regarding the modification of the steel casting by fine titanium-carbonitride powder in the mold are presented. The influence of such modification on the performance of the high-manganese steel is considered, in terms of improved abrasive and impact–abrasive wear resistance. Metallographic data explain the basis for the improved performance of the high-manganese steel. The influence of the thermal conditions in the mold is considered: in particular, the influence of the rate of alloy cooling in the mold on the performance of the modified high-manganese steel. Finally, on the basis of the research findings, recommendations are made for improving the performance of cast high-manganese steel products. In addition, recommendations are made regarding the optimal consumption of titanium-carbonitride powder so as to obtain the required microstructure and properties of the high-manganese steel.

Cyclic deformation fields interactions between pores in cast high manganese steel

Cast pores are known to cause stress/strain concentrations, facilitating the initiation of fatigue cracks and shortening the fatigue lifetime of cast materials; however, it is an open question regarding how the deformation fields generated by different pores interact each other and evolve with fatigue loading. The present study addresses the local deformation behavior in cast-pore containing high manganese steel during fatigue loading investigated using single- and multi-pore finite-element models. These models take into account the actual size, shape and distribution of pores based on X-ray computed tomography images and consider the actual material properties of the steel, i.e. the high strain-hardening rate, cyclic hardening law and Bauschinger effect using a viscoplastic constitutive model within the framework of Chaboche model. The results demonstrate that the local stress, strain and hysteresis loop energy around an actual pore evolve progressively with fatigue loading, and reach as large as 2 to 4, 2.5 to 8.5 and 6 to 30 times their corresponding far-field values at high fatigue cycles. More importantly, two different effects, i.e. "umbrella-like stress shielding" and "overlapping stress amplifying", are identified in the presence of multiple pores, due to the deformation fields interactions between pores. And, which of the two effects takes place or predominates depends on the specific location of concern and the spatial distribution of pores. These findings may be extended to provide some new insight into the fatigue damage micromechanisms in various cast-pore containing materials and to help understand the scatters of their fatigue lifetime in terms of the local deformation fields around pores and their interactions.

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.

Forging of High-Manganese Steel Crossing

The thermoplastic characteristics of high-manganese steels with different phosphorus and sulfur contents were investigated. The zero-ductility temperature and plasticity-temperature range of the high-manganese steels were reduced significantly with increase in phosphorus or sulfur content. The relationship between the initial forging temperature of the high-manganese steel and the content of phosphorus and sulfur can be expressed as Tift = 1200 – 1530wS – 1650wP. The final forging temperature is 900°C, and the heating rate during the forging of the high-manganese steel crossing must be slow. The lifetime of the forged high-manganese steel crossing was almost doubled compared with conventional cast high-manganese steel crossing.

Changes in Impact Strength and Abrasive Wear Resistance of Cast High Manganese Steel Due to the Formation of Primary Titanium Carbides

Changes in Impact Strength and Abrasive Wear Resistance of Cast High Manganese Steel Due to the Formation of Primary Titanium Carbides

THE EFFECT OF PRESSURE – ROLLING OF WELDED TURNOUTS AND RAILROADS ON THEIR WEAR RESISTANCE

The article presents the effect of cold-rolling welded joints in railway lines on their mechanical and tribological properties. Welded joints of high-manganese Hadfield cast steel (L120G13) and normalized rail steel (R350HT) with austenitic steel coupling (X12CrNi17-7) were tested. The conducted tests allowed the hardness profile of the treated surfaces to be studied, as well as the wear resistance and coefficient of friction. The results were compared to the base materials and exhibited hardness enhancement in 80% of cold-rolled surfaces and, moreover, reduced abrasive wear resistance.

Microstructure of Cast High-Manganese Steel Containing Titanium

Abstract Widely used in the power and mining industry, cast Hadfield steel is resistant to wear, but only when operating under impact loads. Components made from this alloy exposed to the effect of abrasion under load-free conditions are known to suffer rapid and premature wear. To increase the abrasion resistance of cast high-manganese steel under the conditions where no dynamic loads are operating, primary titanium carbides are formed in the process of cast steel melting, to obtain in the alloy after solidification and heat treatment, the microstructure composed of very hard primary carbides uniformly distributed in the austenitic matrix of a hardness superior to the hardness of common cast Hadfield steel. Hard titanium carbides ultimately improve the wear resistance of components operating under shear conditions. The measured microhardness of the as-cast matrix in samples tested was observed to increase with the increasing content of titanium and was 380 HV0.02 for the content of 0.4%, 410 HV0.02 for the content of 1.5% and 510 HV0.02 for the content of 2 and 2.5%. After solution heat treatment, the microhardness of the matrix was 460÷480 HV0.02 for melts T2, T3 and T6, and 580 HV0.02 for melt T4, and was higher than the values obtained in common cast Hadfield steel (370 HV0.02 in as-cast state and 340÷370 HV0.02 after solution heat treatment). The measured microhardness of alloyed cementite was 1030÷1270 HV0.02; the microhardness of carbides reached even 2650÷4000 HV0.02.

The Effect of the Cast High-Manganese Steel Primary Structure on its Properties

The article deals with the effect of the wear coefficient of high-manganese steel on service durability indicators of castings, which are produced from this steel and operate under conditions of intensive wear. The article introduces the results of computer simulation of crystallization and cooling processes in high-manganese steel castings in the mould. The effect of the casting cooling rate in the mould on the cast steel primary structure, as well as on the value of its wear coefficient has been studied. The effect of primary crystallization on austenite grain size and its microhardness has been examined and the crystallization rate resulting in the formation of a uniform structure of the alloy has been determined. The effect of cooling rate of high-manganese steel in the temperature range of the precipitation of proeutectoid constituents on their quantitative characteristics and morphology, as well as the hardness of the alloy as a whole has been examined.

Characteristics of excess phase in cast high-manganese steel

The formation of the excess phase in high-manganese steel is considered over a wide range of cooling rates. This phase, which consists of a phosphide eutectic and secondary carbides, may be deposited both along the grain boundaries and within the grains. At low cooling rates, the phosphide eutectic is mainly formed, with a small quantity of secondary carbides. In addition, excess phase with mixed morphology is encountered. It consists of the eutectic and secondary carbide, with a coherent boundary between them. With increase in the cooling rate, the excess phase consists primarily of secondary carbides; its size is reduced. The influence of the cooling rate on the chemical composition of the excess phase is also of interest. Increase in cooling rate is found to reduce the manganese content in the secondary carbides deposited. The ratio between iron and manganese in the phosphide eutectic does not depend on the cooling rate and is practically constant.

RESEARCH OF THE REGULARITIES OF FORMATION, MORPHOLOGY AND CHEMICAL COMPOSITION OF THE EXCESS PHASE IN CAST HIGH-MANGANESE STEEL

The article reviews the regularities of formation of the excess phase in the cast high-manganese steel in a wide range of cooling rates. It was found that this phase can stand out both along grain boundaries and within them and it can be represented by phosphide eutectic and by secondary carbides. At low cooling rates of the casting the phosphide eutectic and a small amount of secondary carbides are mainly formed, moreover, the excess phase with mixed morphology is also formed. It consists of eutectic carbides and secondary carbides with coherent boundaries between them. With increasing of cooling speed the excess phase is allocated predominantly in the form of secondary carbides, wherein there is a decrease in its size. Influence of cooling speed of a casting on the chemical composition of the excess phase also was studied. It was determined that due to increasing the cooling rate the amount of manganese in the formed secondary carbides decreases. The ratio of iron to manganese in the standing out phosphide eutectic does not depend from the cooling rate and is virtually unchanged.

Resistance to Abrasive Wear and Volume Fraction of Carbides in Cast High-manganese Austenitic Steel with Composite Structure

Abstract Cast Hadfield steel is characterised by high abrasion resistance, provided, however, that it is exposed to the effect of dynamic loads. During abrasion without loading, e.g. under the impact of loose sand jet, its wear resistance drops very drastically. To increase the abrasion resistance of this alloy under the conditions where no pressure is acting, primary vanadium carbides are formed in the metallurgical process, to obtain a composite structure after the melt solidification. The primary, very hard, carbides uniformly distributed in the austenitic matrix are reported to double the wear resistance of samples subjected to the effect of a silicon carbide-water mixture.