Chromium Cast Iron Research Articles

Three-body abrasive wear behaviors and mechanism analysis of Fe–B–C cast alloys with various Mn contents

Fe–B–C cast alloy shows the superior two-body abrasive wear resistance, regarded as the potential candidate for high chromium cast iron. In the present work, the three-body abrasive wear behaviors of Fe–B–C cast alloys with variant Mn addition have been systematically investigated. The results show that, appropriate Mn addition can improve the fracture toughness of M 2 B hard phase by affecting the crystal structure, but hardly sacrifice the hardness. Fe–B–C alloy with 2.0 wt.% Mn has the best three-body wear resistance under different applied loads. Microcutting, microploughing and surface fatigue are the predominantly surface damage forms. Improving the toughness of M 2 B can inhibit the cracking behaviors on the wear surface and the subsurface so as to improve the wear resistance. With the increase of the wear load, the microcutting gradually intensifies to cause more severe material removal; simultaneously, silica abrasive can be seriously cracked into small size so that the wear surface appears smoother under the higher wear load. On the whole, improving the toughness of M 2 B is the effective way to optimize the three-body abrasive wear resistance of Fe–B–C alloy.

Effect of TiB2 addition on microstructure and mechanical properties of a hypereutectic high chromium cast iron

Effect of TiB2 addition on microstructure and mechanical properties of a hypereutectic high chromium cast iron

Optimization of Shrinkage Porosity in Grinding Media Balls by Casting Design Modification and Simulation Technique

Shrinkage porosity or cavity are associated with the solidification of the metal either due to gas/air entrapment or when the shrinkage occurring during solidification is not entirely compensated by the riser. Shrinkage cavities occurring in the casting reduces its strength which leads to unfulfillment of the desired serviceability. In this paper, casting design has been modified using the DISA manual to achieve directional solidification which directly relates to improvement of casting quality. The running of metal from pouring basin into casting along with solidification has been analysed through PROCAST which is a casting simulation software based on Finite Element Method and CAFE (Cellular Automata Finite Element) Model. The feeding system of the casting has been modified in terms of shape and volume to minimize air aspiration effect and promote directional solidification. The model used is of grinding media balls casting of high chromium cast iron. The feeding pattern, feeding velocity and solidification with respect to pouring temperature, pouring rate, ambient temperature and film coefficient has been analysed. The final optimum range of all parameters with corresponding minimum shrinkage porosity in casting was obtained. Main aim was to minimize shrinkage porosity in the main casting, ignoring gating and feeding system. The actual minimization of shrinkage porosity comes out around 56 %.

Hot compression deformation and microstructure evolution of high chromium cast iron based on canning compression

Hot compression deformation and microstructure evolution of high chromium cast iron based on canning compression

EFFECT OF CARBON CONTENT ON MICROSTRUCTURE EVOLUTION AND PROPERTIES OF HYPEREUTECTIC HIGH CHROMIUM CAST IRON

This study is to reveal the influence of the amount of carbon content on the microstructure evolution, mechanical properties, and wear properties of Hypereutectic High Chromium Cast Iron (HHCCI). The results indicated that the carbon content plays a key role in the regulation of carbides in the cast iron microstructure. As the amount of carbon content rises, the primary carbides in the cast iron microstructure become apparently coarser, and the volume fraction of carbides gradually increases. The carbide volume fraction reaches 62% when the carbon content is 5[Formula: see text]wt.%. When the value of the carbon content increases, the accumulation and growth of eutectic carbides in the heat-treated cast iron become more and more obvious. After heat treatment, a large number of secondary carbides will be precipitated from the austenite matrix, in the form of fine particles or short rods, with a dispersed distribution. The macroscopic hardness of HHCCI has increased. When the carbon content is 3.5[Formula: see text]wt.%, the macroscopic hardness is 61.2 HRC, and when the carbon content becomes 5[Formula: see text]wt.%, it reaches 64.3 HRC. The wear resistance of HHCCI increases with the value of the carbon content increases. When the carbon content was increased from 3.5[Formula: see text]wt.% to 5.0[Formula: see text]wt.%, the wear resistance of the material increased by 85.7%. The wear of HHCCI is mainly adhesive wear and fatigue wear, and the wear morphology is mainly spalling pits and wear debris.

Investigation on the Influence of Tempering on Microstructure and Wear Properties of High Alloy Chromium Cast Iron

AbstractMechanical properties, wear resistance and impact resistance of a high-alloy chromium cast iron used in the fabrication of grinding balls have been studied. A rank of tempering heat treatments under several temperatures 500°C, 525°C, 550°C and 575°C was performed after austenitized at 1050°C. The Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) techniques have been used to characterize the microstructures and identify the phases. The wear balls tests were conducted in a rotating drum with a velocity 0.5 r/s. The tribological tests were carried out by evaluated a weight loss as function time. The measurement of the rebound resilience was determined by Charpy impact tests. The results of XRD showed the presence of the martensite, carbides type M7C3and M2C for all tempering heat treated. The hardness of the sample increased after the tempering and reach nearly 65 HRC at 1050°C. In another hand, it decreased after the tempering treatment it could be explained by precipitation of the carbides type M2C.

Fixed and Variable Temperature Super-Solidus Liquid Phase Sintering of High Chromium Cast Iron With 25 Wt.%CR and Its Microstructure

A variable temperature super-solidus liquid phase sintering (SLPS) technique is employed in fabrication of high chromium cast iron (HCCI) with 25wt.%Cr to extend its sintering temperature window. Its microstructure evolution, mechanical properties, and abrasive wear behavior are investigated systemically. The results indicate that the variable temperature SLPS can obtain samples with full density plus fine and uniformly distributed carbide particles, and its carbide volume fraction is increased by 4~5% in comparison with the fixed temperature SLPSed one. Meanwhile, its bending strength and impact toughness can be raised by 8.0% and 16.7%, respectively. Finally, the sintering temperature window for variable temperature SLPS of HCCI is extended by 12 °C, reaching 27 °C.

Microstructural and Erosive Wear Characteristics of a High Chromium Cast Iron

Surface material loss due to erosive wear is responsible for the increased cost of maintenance and downtime in industries. Hence, hardfacing is one of the most valuable and effective techniques employed to improve the wear resistance of heavy-duty components. The present paper investigates the microstructural and erosive wear characteristics of a hypereutectic high-chromium cast iron, considering the erosion resistance, resulting from the impact of micro-sized particles, of both as-received and heat-treated conditions. Micro-sized particles involve the erosion-resistant characteristics of carbide and matrix, contemporary. Due to this, the enhancement of the matrix strength could improve the mechanical support to withstand cracking deformation and spalling. Accordingly, the effect of a destabilization heat treatment on the microstructure was firstly investigated by hardness tests, X-ray diffraction analyses, optical and scanning electron microscopy. Specifically designed erosive tests were carried out using a raw meal powder at an impingement angle of 90°. The resulting superior wear resistance of the heat-treated samples was relayed on the improved matrix microstructure: consistent with the observed eroded surfaces, the reduced matrix/carbides hardness difference of the heat-treated material is pivotal in enhancing the erosion resistance of the hardfacing. The present results contribute to a better understanding of the microstructure–property relationships concerning the erosive wear resistance.

Corrosion Resistance of Selected Cast Iron Grades Under Deposit Mining Conditions

The paper analyzes two types of alloyed cast iron used for pump impellers operated in mine working conditions. The research on corrosion resistance of two cast iron grades resistant to abrasive wear was presented. Tests were performed for chromium cast iron (HCCI) grade EN-GJN HV600 (XCr18) (acc. to EN 12513) and high-silicon cast iron HSCI Grade 1 (acc. to ASTM A 518/ A 518M - 99). Deposit mining is characterized by variable working conditions. Both types of cast iron are resistant to abrasive wear and are suitable for loaded elements (e.g. pump impellers). The paper presents a metallographic analysis of selected cast iron grades based on light microscopy. The chemical composition of the tested cast irons was determined with the Leco GDS 500 spectrometer; C and S content was determined with the CS125 Leco Carbon–Sulfur Determinator. The Si content for HSCI Grade 1 was determined by gravimetric method. Corrosion tests were performed under laboratory conditions. In-service tests of cast impellers were performed under real conditions (working mines applications). Corrosion resistance tests were measured with VoltaLab® Potentiostat (PGP 201). Performed tests resulted in the determination of the usefulness of materials used for dewatering pump impellers in mine working conditions. The results of laboratory tests were verified under the operating conditions of cast impellers. In the conditions of transporting a liquid-solid mixture at the moment of appearance of impurities (e.g. chlorine impurities) in the liquid, the impellers from cast iron HCCI revealed a tendency to pitting corrosion, which explains the exploitation results collected in the mining. After laboratory tests for sample from HCCI, the low value of breakdown potential Eb and repassivation Ecp was concluded which says about the absence of pitting corrosion resistance.

Improvement in microstructure and wear-resistance of high chromium cast iron/medium carbon steel bimetal with high vanadium

In the present study, a high chromium cast iron (HCCI) with high content of vanadium (15 wt.%) as the wear resistance layer was fabricated on the medium carbon steel (MCS) substrate by laser cladding process. The effect of high vanadium addition on microstructure, phase, hardness and wear properties of bimetal were investigated. The results show that the microstructure of HCCI layer was significantly improved and refined with addition of high vanadium. No defect such as microcracks and unbonded regions was observed on the interface of the bimetal. The x-ray diffraction revealed that the HCCI (15 wt.% V) layer consists of α-Fe matrix, (Cr, Fe)7C3 and VC carbides. The SEM images shown that round-like VC particles uniformly distributed on the α-Fe matrix and (Cr, Fe)7C3 are of rod-like with distributed on grain boundary, such micromorphology makes it have higher hardness (883HV) and excellent wear resistance than HCCI layer without vanadium addition.

Analysis of the microstructure of wear resistant chrome cast irons after heat treatment

At the Navoi Mining and Metallurgical Combine, which uses a large number of machine parts for mining operations, the issue of optimizing the compositions of wear-resistant chromium cast irons while maintaining their operational characteristics has arisen. The paper presents the results of studying the phase composition of the cast alloy, as well as the effect of heat treatment of cast iron with a high chromium content on its structure and properties. As heat treatment operations, quenching in various modes and low tempering were used. The study made it possible to systematize the known literature data on the heat treatment parameters of a group of wear-resistant chromium cast irons, as well as to optimize their heat treatment modes for parts operating in mining and processing industry.

Influence of metallic matrix on erosion-corrosion behaviour of high chromium cast irons under slurry impingement conditions

Chromium cast irons (CCI) comprise versatile materials that encompass a range of compositions and microstructures often chosen to promote good wear resistance. There are, however, issues that arise when the cast iron is required to operate in conditions where corrosion, as well as, wear is a factor. This scenario usually results in adapting the composition of the CCI in order to achieve higher chromium content in the metallic matrix and, thereby, to attain the corrosion resistance exhibited by high-Cr stainless steels. This paper comprises a comparison of the corrosive wear behaviour of an austenitic-based hypoeutectic cast iron and a martensitic-based, near-eutectic cast iron with the associated stainless steels, in a saline water under solid-liquid submerged jet conditions. A comprehensive experimental methodology has been adopted including evaluation of the behaviour of the materials in free erosion-corrosion conditions and with the application of cathodic protection. This approach has extended the understanding of the fundamental deterioration mechanisms in different hydrodynamic conditions and has highlighted the complexities of the mechanical/electrochemical interactions occurring during erosion-corrosion. An important feature is the influence of micro-galvanic interactions at phase boundaries. The impact of the findings has been discussed in terms of CCI alloy selection and corrosion control strategies.

Study on cast-weld process and composite interface of bimetal composite roll sleeve

A new method, named bimetal cast-weld composite process, was used to produce the roll sleeves in this works. The roll sleeves comprised the flexible low alloy steel (LAS), the low melting point cast iron surfacing layer (Surfacing layer) and the hard high chromium cast iron (HCCI). The microstructure and mechanical properties of bimetals were characterized. Results showed that the melting point of surfacing layer varied gradiently in range of 1249–1463 °C. When the casting process was finished, surfacing layer disappeared. A straight metallurgical composite layer between LAS and HCCI was formed by controlling the temperature field, which was composed of pearlite. Besides, the microhardness value from LAS to HCCI had a smooth transition, and the impact fracture location was about 6.4 mm away from the composite layer at HCCI. Notably, the diffusion of C atoms and Cr atoms occurred on composite layer, whose diffusion direction was from HCCI to LAS. The width of composite layer was about 20 μm, and no defects such as micro-holes and inclusions were observed.

Effect of alloy powder on the properties of ZTA particles reinforced high chromium cast iron composites

Micrometer scale zirconia toughened alumina particles (ZTAp) reinforced high chromium cast iron (HCCI) matrix composites were prepared by the non-pressure infiltration casting process, which solved the poor compounding of micrometer scale ceramic particle preforms under seepage. The effects of the microstructure and the mechanical properties of ZTAp reinforced HCCI matrix composites by micro-powder contents in the preforms were systematically investigated. Alloy powder content of 65 wt.%, 55 wt.%, 45 wt.%, 35 wt.% and 25 wt.% was added to the composite material respectively. Phases of the composites was identified by optical microscope (OM), energy dispersive spectrometer (EDS) and x-ray diffraction (XRD). The best compressive properties of the composites were obtained when the content of alloy powder at 45 wt.%, which the strain reached 6.32% with a stress of 1229.63 ± 39.05 MPa. The fracture mechanism of the ZTAp reinforced HCCI composites mainly was brittle fracture and the ductile fracture was minor. This study shows that the addition of micrometer powder was contributed to improve the organization and properties of the ZTAp reinforced HCCI matrix composites. The reinforcement mechanism of composites not only depends on the load sharing of the reinforcing particles, the strength of the matrix was also critical.

Microstructure and erosion wear properties of high chromium cast iron added nitrogen by high pressure in alkaline sand slurry

Erosion wear is a common and serious problem in slurry transportation field. In order to improve the erosion wear performance of high chromium cast iron (HCCI), a new type of high chromium cast iron with 0.38% nitrogen (HCCI–N) was fabricated by vacuum induction positive pressure melting furnace under 0.4 MPa nitrogen partial pressure on the basis of the established pseudo-binary phase diagram of (Fe–27Cr-2.2C)–N alloy system. The microstructure and erosion wear behavior of HCCI–N were researched in alkaline sand slurry. Results show that the microstructure of HCCI–N has the characteristics of multi-scale and multi-type carbides, including eutectic M7C3 (~20 μm), secondary M23C6 (~2 μm) and Cr2C (~1 μm), distributed in matrix composed of martensite and austenite. A sandwich structure of M7C3-ferrite-martensite was formed at the interface of eutectic M7C3. The nitrogen element is mainly distributed in matrix. The Cr2C (−1011) is coherent with Martensite (110). The erosion wear is caused by the synergy of corrosion and wear. The pure wear rate (Ve) of HCCI–N accounts for 71%–93% of total erosion wear rate (Vt) under different test conditions, indicating that wear loss mainly results from the mechanical action under alkaline sand slurry. Nevertheless, the synergism rate of corrosion and wear (Vs) is also significant to Vt, which accounts for 7%–29% of Vt for HCCI–N relative to 13%–31% of HCCI. The HCCI–N has more excellent erosion wear resistance compared with that of HCCI under all the test conditions, and the optimal wear resistance of HCCI–N is 1.34 times that of HCCI. The nitrogen and chromium dissolved in matrix improves corrosion resistance, and reduces the synergistic rate of corrosion and wear. Multi-scale carbide strengthens the matrix and resists mechanical wear. The combined action of the two factors makes the HCCI–N have excellent erosion wear resistance.

Microstructure and abrasive wear properties of high-vanadium-chromium wear resistant alloy

To enhance the wear resistance of high chromium cast iron (HCCI, Cr26), a new wear resistant alloy with high vanadium and chromium contents (HCCI-V, 15Cr5V4MoSiMn) was designed and prepared by sand mold casting. The microstructure and the phase composition were analyzed by SEM, EDS and XRD, and the abrasive wear property was tested compared with HCCI. Results show that the new wear resistant alloy is characterized by multi-scale and multi-type carbides distributed in a metal matrix composed of martensite and retained austensite. The carbides include VC, M7C3, M2C and M23C6 (M stands for (Cr, Fe)), with dimensions ranging from tens of nanometers to tens of micrometers. The hardness and impact toughness of HCCI-V are 65 ± 0.2 HRC and 10 ± 0.12 J cm−2, respectively, far higher than that of HCCI (57 ± 0.2 HRC, 8 ± 0.12 J cm−2). When the abrasive particle size and load are 6.5 μm and 1.41 MPa respectively, the wear weight loss of HCCI and HCCI-V are 5.6 ± 0.1 mg and 0.8 ± 0.1 mg respectively, and the relative wear resistance of HCCI-V is 7. The excellent wear resistance of HCCI-V is attributed to the multi-scale carbides. The micro-scale carbides resist scratch, and the nano-scale carbides strengthens matrix. The multi-scale carbides can work collaboratively to resist abrasive wear efficiently.

Effect of centrifugal casting temperature on the microstructure and properties of ZTAP/HCCI matrix composites

In the centrifugal casting process, the casting temperature parameters affected the microstructure characteristics, and the performance of the materials was greatly significant. ZTA (ZrO2 reinforced Al2O3) particles reinforced HCCI (High chromium cast iron) matrix composites with honeycomb structure were obtained by centrifugal casting. With the increased casting temperature (1450 °C, 1500 °C, 1550 °C, and 1600 °C), the austenite equivalent diameter size was 43.5 μm, 34.8 μm, 33.1 μm, 22.3 μm respective in the compound area and 58.3 μm, 63.1 μm, 65.2 μm, 71.5 μm respective in substrate area. The average size of eutectic carbides in the compound area decreased from 5.7 μm to 2.5 μm with the casting temperature increased. Meanwhile, the lattice constants of austenite and carbide increased with the increased temperature. The hardness of the composites increased by 4 ∼ 6HRC with a change in casting temperature. The results of three-body abrasive wear under high-stress static load conditions showed that the wear volume loss of the composites reduced with the temperature increased and the wear resistance was 1.4 times at 1600 °C than that at 1450 °C.

Electron microscopy study of carbides precipitated during destabilization and tempering heat treatments of 25 wt.%Cr-0.7 wt.%Mo high chromium cast irons

The effect of a 0.7 wt.%Mo addition on the microstructure and hardness of a heat treated 25 wt.%Cr–2.4 wt.%C cast iron has been studied via comparison with a Mo free reference 25 wt.%Cr–2.4 wt.%C iron. Destabilization led to precipitation of M7C3 and M23C6 secondary carbides in the reference iron, whereas M23C6 secondary carbide was found in the iron with 0.7 wt.%Mo. Tempering resulted in additional secondary carbide precipitation and formation of ferrite. Secondary hardening was found in the iron with 0.7 wt.%Mo. For the destabilized + tempered condition the macro-hardness of the iron with 0.7 wt.%Mo addition was higher than the reference iron due to a finer and denser distribution of secondary-carbides.

Microstructural Characterization, Tribological and Corrosion Behaviour of Forged and Cast Grinding Balls a Comparative Study

Various facilities are used in mineral processing to prepare raw material. Practically, two types of balls are used, cast balls and forged balls. They are respectively made from high chromium cast iron and forged steel and are supplied in different sizes and chemical compositions. The cast and forged balls have different microstructures and consequently display dissimilar wear behavior. The target aimed in this work is to achieve a comparative study taking into account the type of microstructure, mechanical properties, and wear behavior of these two kinds of materials. Specimens have undergone chemical, metallographic and XRD characterizations. Subsequently, these samples were subjected to hardness measurements, abrasion and friction tests in order to evaluate their wear behaviour. Tribological tests, under unlubricated environment, are carried out on both types of grinding balls in order to study the wear system. Corrosion tests are also performed on forged steel and high chromium cast iron ball samples. The obtained results reveal a large difference in terms of chemical composition and microstructural components. Chromium cast iron balls are more resistant to friction, whereas forged balls are more resistant to abrasion. Additionally, the corrosion tests reveal a narrow discrepancy in corrosion behaviour between the studied materials.

Analysis of Carbides in Multi-component Cast Iron Design Based on High Entropy Alloys Concepts

Nowadays, the concept of high entropy alloys (HEAs) has expanded the limits of metallurgy and high-quality metallurgical HEAs ingots have already been successfully obtained on an industrial scale. High Chromium Cast Irons (HCCI) and Multi-Component Cast Irons (MCCI) are known to be a useful material for applications when abrasion resistance is required. Inspired by the concepts of high-entropy alloys, a base HCCI was modified, by adding other carbide-forming elements, at concentrations higher than what is currently used, in order to develop a new class of white cast iron, High Entropy White Cast Iron (HEWCI). The characterization of carbides precipitated during the HEWCI solidification was performed by scanning electron microscopy, energy dispersive spectroscopy, electron backscattered diffraction (SEM/EDS/EBSD) and X-ray diffraction (XRD). With the characterization techniques employed, the as-cast microstructure obtained of HEWCI is composed of approximately 50% of austenite matrix and 50% of different types of carbides, MC, M7C3 and M2C carbides.