High Chromium Cast Research Articles

STUDY OF HIGH CHROME WHITE SHEEP DEPENDENCE ON CARBONE QUANTITY AND ABRAZIVE CONDITIONS

In addition to studying the properties of abrasive corrosion-resistant alloys, the article considers it important to study the abrasive corrosion-based effect of abrasive corrosion resistance of high-chromium white cast iron on the amount of carbon and the dependence of abrasive particles on carbide and particle dependence. At the same time, the spread of white cast iron with 1.5 - 30% Mo is higher, which makes it easier to spread the processed martensite cast iron. Açar sözlər: oil drilling equipment high chromium alloy, abrasive particle, diffusion resistance, hardness, erosion coefficient, abrasive conditions.

Effect of the Morphology, Size, Distribution and Homogeneity of Carbides and Matrix on Wear Resistance in High Cr-Alloys White Cast Iron

The aim of this work was to study the wear behavior of high-chromium white cast iron of families ASTM A-532 II (B, D) and III A, used in mining equipment, in order to establish relationships between the wear resistance, hardness and microstructure of the alloys, with the ultimate purpose of predicting their resistance to abrasion. Samples from these cast irons were subjected to mechanical wear tests by rotating drum, then their micro/macro hardness was measured and microstructure analyzed by optical and scanning electron microscopy .It was found that when the macroscopic hardness differences were significant there was a strong correlation between the hardness and the loss of mass due to abrasion-impact wear. By contrast, when the alloys had similar hardness, the wear resistance was determined by morphology, size, and the distribution and connectivity of carbides and matrix and therefore was not predictable by an only simple hardness test.

Optimization of the composition and structure of wear-resistant white cast irons used in the mining industry

The mining industry of Uzbekistan uses hundreds of tons of white wear-resistant cast iron monthly for the manufacture of parts for machinery and equipment that extract natural raw materials. Only the Production Association Navoi Machine-Building Plant (PO «NMZ») monthly produces cast parts from wear-resistant high-chromium alloyed white cast iron with a volume of more than 120 tons per month. Most of the parts are made for rock crushers; their wear during work in mines shortens the service life of machinery and equipment. Parts of foreign equipment: dredge pumps, lining of grinding mills, hydraulic transport and others are made of white cast iron, highly alloyed with chromium, nickel, copper, titanium and other chemical elements. The annual import into the republic of parts made of cast irons of complex chemical composition requires signifi cant costs. In order to save money by refusing to import parts, a domestic wear-resistant white cast iron of grade 280Kh29NL was developed, from which rubbing parts, operating under wear conditions in mines, for mining equipment are cast in the foundry of the Navoi Machine-Building Plant. Considering that ferroalloys for the production of cast iron are also imported, the cost savings in the production of mining equipment parts instead of worn-out ones is insignificant. The purpose of this work is to optimize the composition of highly alloyed wear-resistant white cast iron for its replacement in industry with an economically alloyed analogue, as well as to improve the structure of the composition-optimized white wear-resistant cast iron to obtain the required level of performance properties of parts operating under friction and wear conditions. For this, phase transformations, the structure and properties of white cast iron, and the conditions for casting parts were studied. Based on the research results, recommendations were developed for economical alloying and casting technology for friction and wear parts.

Effect of temperature and rolling rate on high chromium cast iron/low carbon steel composite plate prepared by hot rolling

Effect of temperature and rolling rate on high chromium cast iron/low carbon steel composite plate prepared by hot rolling

Technological Improvement of Surfacing of Parts of Hammer Crushers Used in Coke-Chemical Industry

A technology of manufacturing surfacing with high-chromium special cast iron without heating is developed; the main directions for improving surfacing quality are outlined. It is proposed to replace manual arc welding with plasma surfacing using high-speed hard surfacing materials.

Morphology and Material Properties of Carbides in High (24%) Chromium Cast Iron

Morphology and Material Properties of Carbides in High (24%) Chromium Cast Iron

The structure and mechanical properties of the high chromium and nickel content cast alloy after long duration work in high temperature

In the petrochemical industries cast steel tube coil sheets with high chromium and nickel content are used. The operation range of these alloys are 533 to 1150°C. A paramount for these alloys are: - corrosion and scaling resistance at high temperatures; - dimensional stability, i.e. resistance to warping, cracking and thermal fatigue; - resis-tance to plastic flow, i.e. creep strength. Tube coil sheet of furnace resulting in aggregate failures have been consid-ered. Life span of the studied specimens obtained from tube coil sheet was 3 years. After a few years of exploita-tion several hollow cracks on the heater tube-sheet were identified. Pre-oxidation of the tubes surface are possible and it has not only favourable effects: during cooling cracks may form in the oxide layer. The aim of the per-formed research was to characterize the microstructure and mechanical properties of the investigated alloy after ageing at the temperature of 900°C. The high temperature determine elements diffusion in the structure, emergence of chromium and niobium carbides and other precipitates and cause the changes in the mechanical properties. DOI: http://dx.doi.org/10.5755/j01.mech.19.6.5986

Effect of Tempering on the Oxidation Resistance of a Work Roll Grade High-Chromium White Cast Iron

The high-temperature oxidation resistance of as-cast and heat-treated specimens of a high-chromium white cast iron for hot mill work rolls was investigated by gravimetric means under isothermal oxidation conditions in dry air at 650 °C. Results from the experiments revealed that the chromium content of the matrix and the carbide area fraction of the samples significantly affect the extent of oxidation. Even so, the oxidation phenomenon could always be described by the parabolic rate law. The surface morphology and cross-section of the samples were studied by means of X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analyses, confirming that the oxidation behaviour of the alloys is sensitive to tempering heat treatment schedule. The impact of heat-treatment on the oxidation resistance of the work roll alloys is discussed in terms of their microstructural modification.

Research of Composite Coating Composed of Mo Wire and High-Cr Cast Iron Made by Laser Cladding Technology

The experiments of laser cladding on the surface of H13 steel were made. Molybdenum (Mo) wire and high-chromium (Cr) cast iron powder were used as cladding material. The microstructure and hardness of laser cladding layer were studied. The experiments showed that Mo wire and high-Cr cast iron cladding layer had better properties such as minute crystals, high density, no crack, no gas cavity and good metallurgical bonding with base metal. There was a slight melting on the surface of Mo wire which would greatly increase the binding force between Mo wire and high-Cr cast iron. Mo wire could make grain refine and limit the growing of carbide. The average hardness of junction zone of Mo wire and high-Cr cast iron was 750HV0.2 which was higher than that of cladding zone composed of high-Cr cast iron (650HV0.2).

The Effect of Microstructure on Unidirectional Chilled Solidification of High Chromium White Cast Iron

This study mainly investigates the characteristics of carbide and the matrix structure of ASTM A532–87 CLASS Ⅲ high-chromium white cast iron under directional solidification. The two components of high-chromium white cast iron were put in a 3-level Furan sand model, which is placed in a cold-water circulation copper model, producing unidirectional chilled solidification. A K-type thermocouple is employed to measure data for solidification temperature with time. The move velocities of the liquidus phase and solidus phase is calculated. The matrix and the growth characteristics of M7C3 carbide are explored. As determined from the experiment, the liquidus temperature gradient GL is 0.45~ 0.9oC/mm, and the solidus temperature gradient Gs is 4.3~6.2oC/mm. Around 300 nm of the primary carbide is formed from the added elemental nickel being less than 0.3 mm from the chilled end and from the nickel-free alloy being less than 5 mm from the chilled end. As the distance from the chilled end increases, the primary carbide gradually becomes coarser, and the distance between eutectic carbide groups is increased. This study employs EPMA to analyze the changes of primary carbide, eutectic carbide and matrix components with distance from the chilled end, as well as changes in the distributions of chemical elements.

High temperature oxidation mechanism of a 3%Ni cast stainless steel

In this work, the high temperature oxidation mechanism of a high chromium (28 wt-%) cast stainless steel containing 3%Ni, and with an austenitic–ferritic microstructure, has been studied and compared to that of a ferritic stainless steel with similar chromium and carbon contents but without any nickel additions. Two different oxidation temperatures (800 and 970°C) were selected for both the as cast and annealed (600°C for 2200 h) conditions. The oxidation mechanism of the Ni-containing duplex alloy has been found to involve the formation of four successive layers:(i) the external scale exhibiting the crystalline structure of Cr2O3(ii) a single phase metal layer in contact with the oxide and consisting of austenite(iii) a decarburised zone exhibiting a two phase structure of ferrite and austenite(iv) the initial alloy microstructure consisting of ferrite, austenite and alloy carbides.The oxidation resistance of the austenitic–ferritic alloy is in all cases 50–100% higher than that of the ferritic alloy, while that of the annealed samples (all other experimental conditions remaining constant) is ten times higher than that of the as cast samples.

Microstructure of vanadium-, niobium- and titanium-alloyed high-chromium white cast irons

In the present work, additions of 2% vanadium, 2% niobium and 2% titanium were respectively made to a high-chromium white iron (17% Cr) to analyse the effect of these elements on the as-cast structure of the alloy, and their influence on the material's hardness. This study was carried out for different solidification rates, so the alloys were cast into wedge-shaped copper moulds. The recorded solidification rates for the ingots ranged from 1.5 K sec−1 for a 2 mm thickness section, to 35 K sec−1 for a 40 mm section. It was found that the addition of these carbide forming elements considerably increased the alloy's hardness by different mechanisms. Vanadium was shown to partition completely to the eutectic carbide phase which increased hardness and the volume fraction of this phase. Niobium and titanium formed extremely hard NbC and TiC respectively, which in turn produced a refinement in the structure and contributed to the increase in hardness of the iron. There was no evidence that these elements influenced the size and morphology of the eutectic carbide M7C3 for the experienced solidification rates.

Application and performances of graphitic chromium cast iron rolls

The main requirements for the development of a new grade for the later finishing section of the mill are : good oxidation and thermal behaviour, high wear resistance, good resistance to rolling incidents. The approach of Marichal Ketin to improve the rolling performances in the last finishing stands is presented. The Hi-Cr cast iron possesses excellent wear resistance due to the presence of hard chromium carbides, but its thermal conductivity and sticking properties are fairly low. A graphite precipitation could contribute to an improvement in thermal conductivity and serve as lubricant preventing sticking. The new material, called graphitic chromium iron, shows good oxidation, wear and thermal behaviour allowing its use as work roll in the last stands of the finishing section of a HSM. In the as-cast condition, graphite precipitation in high Ni and Si chromium cast iron occurs at a temperature of 950 °C. Moreover, the amount and volume of free graphite may be increased by secondary graphite precipitation during suitable heat treatment.

Structure, nucleation, growth and morphology of secondary carbides in high chromium and Cr-Ni white cast irons

Heat-treated high chromium and Cr-Ni white cast irons are widely used by the mining and mineral industries for impact and abrasion resistance. With certain heat treatments, Fe-Cr carbides are precipitated within the chromium- and carbon-rich austenitic matrix, thereby destabilizing the austenite which transforms substantially to martensite on subsequent cooling. The crystal structures of these carbides were determined indirectly by referring electron microprobe analyses of the austenitic matrix to the appropriate isothermal solid-state sections of the Fe-Cr-C phase diagram and directly by microprobe analyses of exposed secondary carbides. The nucleation, growth and morphology of these carbides were studied by a combination of selective removal of the austenitic matrix and subsequent scanning electron microscopy of the exposed carbides.

Metallographic etching for carbide volume fraction of high-chromium white cast irons

Metallographic etching for carbide volume fraction of high-chromium white cast irons

A Portable Slurry Wear Test for the Field

A new portable slurry wear test apparatus developed by the Bureau of Mines, U.S. Department of the Interior, makes it possible to gather materials wear and corrosion data at a mineral processing site. The portable wear cell is identical in design to a laboratory cell reported previously. It allows simultaneous evaluation of 16 specimens in a continuous flow of fresh slurry. Data obtained from selected metals and polymers showed high-chromium white cast irons to perform particularly well in tests with an aqueous lead-zinc sulfide ore slurry. However, ultra-high-molecular-weight polyethylene that exhibited superior wear resistance in comparable laboratory tests with an aqueous slurry of silica sand did not perform as well in field tests. Such results show how misleading it can be to use laboratory data to predict relative rates of wear in industrial slurries, even under nominally identical flow conditions. Field testing is therefore needed. In situ electrochemical corrosion measurements on a low-alloy steel showed that the field and laboratory slurries were similarly corrosive.

Effect of boron on the phase composition of high-chromium white cast irons

Effect of boron on the phase composition of high-chromium white cast irons

Phase composition of high-chromium white cast iron

The change in hardness after annealing of cast iron and after normalization at temperatures up to 1100° is due to the structural condition of α phase, while the reduction of the hardness when the normalization temperature is raised from 1100 to 1200° is due to the appearance of austenite. The presence of a substantial amount of austenite also explains the low hardness of the cast iron in the cast condition as compared with the hardness after normalization at 1000–1100°. The high hardness of the cast iron normalized at 1000–1100° may be due partially to the precipitation of secondary carbides.

Structure and properties of high-chromium white cast irons

1. The highly alloyed austenite produced in the alloys investigated, especially alloys 2 and 3, is very stable. The amount of austenite can be reduced only by combined heat treatment. 2. The optimal quenching temperature for all the alloys investigated is in the range of 900–975°. 3. After quenching, all the alloys should be tempered at 450–550°, which produces a hardness above HRC 60 and increases the resistance to abrasive wear.

CANNON-MUSKEGON D-2

Abstract CANNON-MUSKEGON D-2 is a high-carbon high-chromium air-hardening cast tool steel with excellent resistance to abrasion. It is moderately machinable with excellent non-deforming characteristics. A higher silicon content is permissible in this cast steel than in AISI D2 (wrought) tool steel. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance as well as casting, heat treating, machining, and joining. Filing Code: TS-259. Producer or source: Cannon-Muskegon Corporation.