Electroslag Casting Research Articles

Microstructure and Mechanical Properties of Modified M2 High‐Speed Steel by Adding La2O3 in the Electroslag Casting Process

An electroslag casting method is used to add rare‐earth La to M2 high‐speed steels by adding La2O3 into the molten slag. The effects of the La content on the microstructure and mechanical properties of M2 high‐speed steel are studied. The results show that rare‐earth La is effectively added to steel by taking advantage of the decomposition of La2O3. The rare‐earth La partially modifies the pre‐existing oxide and sulfide inclusions into small and spherical rare‐earth oxysulfide inclusions. By adding an appropriate amount of La, the as‐cast iron dendrite matrix and coarse eutectic carbides can be refined, the carbide content is reduced, the carbide network is broken, and the decomposition of M2C into M6C and MC is promoted. After heat treatment, the network breaking and spheroidalization of the carbides are further facilitated, and the carbide content is reduced. The impact toughness and bending strength of the studied samples are improved by modifying the inclusions and optimizing the microstructure.

Electroslag heating and additional melt feed of steel ingots of semi-continuous casting

The issues related to the continuous compensation of metal shrinkage during its crystallization are studied. Based on the evaluation of ways to reduce the size of the shrinkage shell, aimed at maintaining the liquid phase for a long time, the most effective ways to reduce the size of the shrinkage shell and reduce the head trim are selected. The influence of electroslag heating and recharge technology on the length of the shrinkage shell and the quality of the metal of the sub-shrinkage area of semi-continuously cast ingots has been studied. The study was carried out on ingots with a diameter of 500 mm weighing 3.5 tons of carbon and alloy steels. The installation consisted of 3 electrodes with a diameter of 75–100 mm, connected to the transformer TSH-3000-3. The transformer power was 570 kVA, the current per phase was 1000–3000 A, the voltage on the electrodes was 40–60 V. Temperature measurements were carried out in the copper sleeve of the mold. For comparison, the temperatures in the walls of the mold were recorded during the cooling of the ingot in the mold without heating. The cooling curves showed that the process of electroslag heating does not cause overheating of the mold walls. This is explained by the appearance of a side metal crust in the upper part of the ingot, which does not melt with liquid slag and protects the walls of the mold. The surface of the ingots had no visible defects (crust inversions, film and slag inclusions). Additional surface treatment (stripping, stripping) was not required. The macrostructure of the ingots is dense, without visible defects, including in the axial zone. Sulfur liquation on sulfur prints according to Bauman was not detected. Electroslag heating had a significant impact on the length and shape of the shrinkage shell. The results obtained show that electroslag heating with graphite electrodes, feeding with consumable steel electrodes of the same composition with the resulting ingot and electroslag casting of steel can improve the structure, density and chemical homogeneity of cast metal, reduce the content of non-metallic and gas inclusions and significantly increase the yield of usable compared to conventional casting.

The formation of alloy based on Al-Ti-B system by electroslag process involving dispersed engineering waste

In this article presents technological process of manufacturing Al-Ti-B rod master alloy by electroslag casting is proposed and investigated. Aluminum alloy chip waste of a grade AK7, commercial titanium of a grade VT1-00 and amorphous boron of a grade A were used as starting materials. The consumable electrode is a product in the form of a rod obtained by mouthpiece pressing of a mixture of crushed starting materials in a mass ratio of AK7 : VT1-00 : amorphous boron = 97:2:1. According to the proposed technology and the ratio of starting materials in the charge composition, an experimental bar material of the Al-Ti-B ligature was obtained, electron microscopic, micro-X-ray spectral studies, the stereometric analysis of the structure which showed the priority interaction of titanium with boron.

Optimization of modification of silumin alloy with Al-Ti-B ligature obtained from dispersed wastes of mechanical engineering by electroslag casting

In this research the process of modifying the AK7 alloy with an experimental master alloy based on the Al-Ti-B system, made from machine-building chip waste, using a combination of powder metallurgy and electroslag casting processes, was studied and optimized. The adequate linear model was obtained on the basis of the study, carried out according to the plan of a full factorial experiment, in which the controlled factors were: the mass ratio of titanium- and boron-containing materials in the charge composition. The role of the solvent in the charge composition was played by the chip waste of the AK7 cast alloy.The response of the cybernetic system was the size of the cast grain of the modified AK7 alloy. The grain-grinding effect of controlled factors has been established. The minimum possible size of the cast grain of the modified AK7 alloy is established with a 95% probability at the level of 250 microns.

Влияние состава шихтовой композиции электрошлакового процесса получения лигатуры Al-Ti-B на её структуру

Modifying ligature formulation based on the Al-Ti-B system, involving the use of a complex of powder metallurgy and electroslag casting processes has been viewed. This complex makes it possible to obtain a rod ligature from the chip machine-building scrap, where elements Al and Ti are in a reduced state.

Mechanical properties of intermetallic alloys of the Fe – Al system obtained by a combined process from dispersed wastes of mechanical engineering

The article describes the combined process of obtaining intermetallic alloys of the Fe-Al system from dispersed wastes of mechanical engineering. This process is based on a combination of electroslag casting with simultaneous self-propagating high-temperature synthesis. The formation of an intermetallic alloy occurs due to the use as a consumable electrode of a thin-walled steel tube filled with a charge consisting of a mixture of dispersed mechanical engineering waste (chip waste of steel, silumin, forge cinder, fluorspar), ground to a powdery state. Intermetallic compounds of the Fe-Al system have a unique high complex of physical-mechanical and service properties, they can effectively resist the corrosive effects of aggressive media and abrasive wear. These properties of the materials are of practical interest for a wide range of engineering industries. The materials based on iron aluminide Fe3Al should be especially noted. These materials have a low density (~6.7 g/cm3) in comparison with many high-temperature complex alloyed steels and alloys and at the same time their cost is significantly lower. The latter circumstance is due to the fact that in order to ensure a given level of service properties at high temperatures there is no need to use scarce alloying elements. However, there is a rather significant drawback of these materials. It is the brittleness of intermetallic phases, which hinders their widespread use. However, this drawback is leveled by technological methods of synthesizing the materials, leading to a decrease in grain size, elimination of water vapor in charge materials and the gas phase and alloying with chromium. The purpose of this study is to develop the technological foundations for obtaining intermetallic compounds of the Fe-Al system, which differ in the savings of energy and material resources with the recycling of dispersed wastes from mechanical engineering.

Correlation between current and cross-sectional area of parallel fixed-movable dual electrodes in ESC

Electroslag casting with parallel fixed-movable dual electrodes is a new method for achieving better quality of castings in complex mold cavities. In this work, a mathematical model, y=kx2+(k+1)x, was established to describe the ideal correlation between the current ratio (y) and the cross-sectional area ratio (x) of the dual electrodes, where k is the filling ratio. Investigation was conducted on the electroslag casting process with dual electrodes of various cross-sectional areas, but at a constant k value. The experimental results indicated that the ideal correlation was obtained at the stable casting stage, and the fitting results were consistent with the experimental results at certain k values. The experimental findings show that better castings can be obtained when the current ratio is greater than 1.536 and the cross-sectional area ratio is greater than 0.5.

Up-pulling force analysis for ESC hollow cylindrical casting

Electroslag casting (ESC) is an important method to produce high quality castings. In this study, the ESC up-pulling inner mold method (EUPIM) was used to produce hollow cylindrical castings with the multiple consumable electrodes. The radial deformation, the axial and radial internal stress of the inner mold, and the axial internal stress of the slag shell were analyzed using the finite element method (FEM) with the aid of ANSYS software. The ProCAST software was used to calculate the specific heat, heat conductivity and density curve of Cu. Simulation results show that the radial deformation, the axial and radial internal stress of the inner mold, and the axial internal stress of the slag shell near the slag-metal interface of hollow cylndrical casting gradually increase from 0 s to 360 s after the ESC starting (slagging) process but before applying the up-pulling force. The suitable initial up-pulling moment of the inner mold is at around 180–198 s after the starting process.

Research on Filling Channel of ESC by Fixed Consumable Electrode Filling Method

This study takes the consumable electrode, slag bath, and ingot as investigated objects. Mathematical models is established based on the convection thermal transfer equation of the slag bath, the thermal conduction equation of the ingot, and the melt flowing equation,meanwhile the appropriate electromagnetic field, thermal boundary conditions are applied, The numerical simulation study on influence of process parameters on filling channels between metal pools in electroslag casting process with fixed consumable electrode filling method are performed by using large finite element analysis software ANSYS. Size of casting ingot is 400 x 70 x 400, the research show that when the current density of mobile consumable electrode is greater than or equal to 0.5 A/mm², the electrode spacing is less than or equal to 0.15m, and the electrode thickness is greater than or equal to 0.035m, the two metal pools are connected，molten metal of moved consumable electrode casting successfully supply the metal pool of fixed consumable electrode through filling channel, make sure that casting is forming under stable electroslag conditions. the minimum sectional area of filling channel is increased with the increase of current density of the mobile consumable electrode and the cross-sectional area of the consumable electrode.

Use of Centrifugal Electroslag Casting for Producing Cold-Resistant Steel Grade Ring Blanks of Flange Objects

A method is considered for preparing objects of the flange type made of steel of grades 09G2S and 10G2 by centrifugal electroslag casting (CESC). Results are given for chemical analysis and mechanical properties of objects prepared by different methods. The advantage of CESC technology is demonstrated making it possible to prepare cast blanks that with respect to production parameters and physicomechanical properties correspond to the GOST and TU for the given forms of steel having configuration and dimensions close to a finished object.

Application of Mathematical Models for Different Electroslag Remelting Processes

AbstractThe electroslag remelting (ESR) process has been effectively applied to produce high grade special steels and super alloys based on the controllable solidification and chemical refining process. Due to the difficulties of precise measurements in a high temperature environment and the excessive expenses, mathematical models have been more and more attractive in terms of investigating the transport phenomena in ESR process. In this paper, the numerical models for different ESR processes made by our lab in last decade have been introduced. The first topic deals with traditional ESR process predicting the relationship between operating parameters and metallurgical parameters of interest. The second topic is concerning the new ESR technology process including ESR with current-conductive mould (CCM), ESR hollow ingot technology, electroslag casting with liquid metal(ESC LM), and so on. Finally, the numerical simulation of solidification microstructure with multi-scale model is presented, which reveals the formation mechanism of microstructure.

Use of a Developed Production Process of Centrifugal Electroslag Casting For Manufacturing a Reducer

A production process is considered for preparing reducer-type objects from steel grades 17G1S and 09G2S by centrifugal electroslag casting. Analyses of chemical composition and mechanical properties are provided for objects prepared by different technology. The advantage of centrifugal electroslag casting is demonstrated, making it possible to prepare cast objects with physical and mechanical properties corresponding to the State Standard (GOST) and technical specifications for these steel grades having configuration and geometric dimensions close to those of finished objects.

High strength bimetallic composite material fabricated by electroslag casting and characteristics of its composite interface

Bimetallic composite material of bainitic steel and PD3 steel was produced with electroslag casting process, and element distribution of its composite interface was investigated by theoretical calculation and energy dispersive spectrometer (EDS). Results show that the tensile strength (1,450 MPa), hardness (HRC 41-47) and impact toughness (94.7J·cm-2) of bainitic steel were comparatively high, while its elongation was slightly low (4.0%). Tensile strength (1,100 MPa), hardness (>HRC 31) and elongation (7.72%) of the interface were also relatively high, but its impact toughness was low at 20.4 J·cm-2. Results of theoretical calculation of the element distribution in the interface region were basically consistent with that of EDS. Therefore, electroslag casting is a practical process to produce bimetallic composite material of bainitic steel and PD3 steel, and theoretical calculation also is a feasible method to study element distribution of their interface.

Microstructure and property of WC/steel matrix composites

Steel matrix composites (SMCs) with 5CrNiMo steel as matrix and tugnsten carbide (WC) particles as hard phase were prepared by inductive electroslag casting technology. The influence of annealing, forging state and quenching tempering state on the microstructures of the particle-reinforced SMCs were investigated by metallographic analysis method. The particle composition and the composition change of the boundary were tested by energy dispersive X-ray spectroscopy with the scanning electron microscope, and the macro and microhardness were determined by Rockwell hardness tester and microhardness tester. The results show that in most parts of the SMCs, the distribution of WC particles was relatively uniform. White WC particles wrapped around a circle of black stripe Fe3W3C compound carbides. A certain thickness of the transition layer existed on the interface of the WC particle and steel matrix, and two kinds of WC grains for ‘iron rich’ and ‘iron poor’ appeared. The macro and microhardness of the composite material improved significantly than that of the 5CrNiMo steel after inductive electroslag casting.

Numerical Simulation of the Electroslag Casting With Liquid Metal for Producing Composite Roll

The electroslag casting with liquid metal (ESC LM) is a new technology for producing composite roll of high quality based on electroslag metallurgy. In the present work, a two‐dimensional quasi‐steady state mathematical model of just one half of the ESC LM facility is developed due to the axial symmetry. Influences of operating voltage and pouring temperature on the heat transfer of the composite roll system have been studied. The Lorentz forces and Joule heat are combined with the turbulent flow and energy equations via additional source terms in these equations by the user‐defined functions (UDF) based on Fluent software. Simulation results indicate that the distributions of electric potential, current density, Lorentz forces, and Joule heat are concentrated on the upper area of slag bath and a much shallower molten steel pool is obtained. By using the current carrying mold, the heat transfer from slag bath and superheat of the molten steel pool are lower than the conventional ESR process, which is beneficial to a vertical crystallization and an excellent bonding interface between the roll core and working layer of the composite roll. The study of this paper gives us a better understanding of the ESC LM process.

Weld Repairs of the Electroslag Casting Red Copper Crucible

The paper analyses the manufacturability and difficulties in weld repairs of the electroslag casting red copper crucible with bent axle, work out the relevant measure. It is proved by experiment that large red copper product can be perfectly repairs by use suitable welding procedure.

Effect of double quenching and tempering heat treatment on the microstructure and mechanical properties of a novel 5Cr steel processed by electro-slag casting

The effect of double quenching and tempering (DQT) treatment as well as conventional high temperature quenching and tempering (CQT) treatment on the microstructures and mechanical properties of low carbon 5Cr martensitic as cast steel produced by electroslag casting was investigated. The microstructure changes were characterized by optical microscope (OM), scanning electron microscope (SEM), electron back scatter diffraction (EBSD) and transmission electron microscopy (TEM). The characteristics of carbides precipitated during tempering were analyzed on both carbon extraction replica and thin foil samples by TEM. The mechanical performance was evaluated by Vickers hardness test, tensile test, and Charpy V-notch impact test at ambient temperature. The results of microstructure study indicated that DQT treatment led to a finer microstructure than that of CQT. The carbides of the tempered samples were identified as M7C3. The carbides along the prior austenite grain boundaries nucleated directly while those within the laths should be transformed from cementite which formed at the early tempering stage. Compared with CQT condition, yield strength slightly increased after DQT treatment, and impact toughness improved a lot. The strengthening mechanisms were analyzed and it was found that grain refining and precipitation strengthening were mainly responsible for the increase of strength. The superior toughness of DQT condition was attributed to the finer microstructure resulting in more frequent deflections of the cleavage crack and the smaller size of carbides along the prior austenite boundaries. EBSD analysis showed that both martensitic block and packet of low carbon 5Cr tempered martensitic steel could hinder crack propagation, while the latter was more effective.

Abrasive Resistance Study on WC Particles Reinforced Steel Matrix Composite of Engineering Machinery Equipment

The steel matrix composites with 5CrNiMo mold steel as substrate and WC particles as hard phase, were prepared by electroslag melting and casting. The composite material’s properties such as friction factor, wear volume and wear mechanism were investigated by scanning electron microscope (SEM) and friction wear test equipment. The results demonstrate that the sample’s abrasive resistance improved greatly after heat treatment. In the condition of dry sliding wear, surface peeling caused by adhesive wear and adrasive wear caused by wear debris as the third body are the main wear mechanism.

Influence of Heat Treatment Process to Advanced Steel Matrix Composites of Engineering Machinery Equipment

The steel matrix composites with 5CrNiMo steel as matrix and WC particles as hard phase, were prepared by electroslag casting technology.The microstructures of the particle reinforced steel matrix composites on the original casting state, forging and annealing state, and quenching tempering state were researched by metallographic analysis method. The results show that the most parts of the steel matrix composites, the distribution of WC particles was relatively uniform, small pore, no holes, and the material density was very high. The white WC particles wrapped around a circle of black stripe Fe3W3C and WMoC2 compound carbides. A certain thickness of transition layer organization existed on the interface of the WC particle and steel matrix, so as to improves the bonding strength of the phase interface and the strong toughness of materials.

Effects of cooling method after intercritical heat treatment on microstructural characteristics and mechanical properties of as-cast high-strength low-alloy steel

The effect of cooling method after intercritical heat treatment on the microstructures and mechanical properties of as-cast steel produced by electroslag casting was investigated. The microstructure characteristics were analyzed by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscopy (TEM) and electron back scatter diffraction (EBSD). The mechanical performance was evaluated by tensile testing at ambient temperature and Charp V-notch impact tests at various temperatures (−40°C, −20°C, 20°C). The tensile and impact fracture micromechanisms were discussed in details. The results of microstructure investigation indicated that water cooling after intercritical heat treatment led to a mixed microstructure of ferrite and tempered martensite, while a composite microstructure of ferrite and tempered bainite was obtained after air cooling. The carbides of Cr, Mo and Nb in matrix after water quenching were finer than the ones after air cooling. Compared with water cooling, a good balance of strength and toughness was obtained after air cooling. The crack propagation path in the steel after water cooling can propagate along the long axis direction of ferrite bands, directly across the intersecting banded ferrite and martensite as well as along the interfaces between ferrite and martensite. However, the crack propagation path in the steel after air cooling depends on the shape, size and distribution of M/A islands.