Properties Of High Chromium Cast Iron Research Articles

The Melting Process and its Impact on the Properties of High-Chromium Cast Iron and the Economic Calculation

The Melting Process and its Impact on the Properties of High-Chromium Cast Iron and the Economic Calculation

Preparation and Mechanical Properties of High Silicon Molybdenum Cast Iron Materials: Based on Deep Learning Model

In the production and life of machines, wear is the main form of material failure. Many workpieces and equipment will produce friction and wear during use, causing energy and material consumption, resulting in huge economic losses. In the process of using engineering equipment, in order to improve the service life of the workpiece and improve the wear-resistant material, the research of the material itself must be closely linked with the wear mechanism. Among the antiwear materials, the application of high-chromium cast iron is the most common. The reason is that high-chromium cast iron has a series of advantages in performance, manufacturing technology, and price. However, high-chromium cast iron itself has high C content and high brittleness, resulting in defects in toughness and poor corrosion resistance. When working in harsh environments such as mechanical extrusion, high-strength wear, and chemical corrosion, cracking and deformation are prone to occur, corrosion and peeling, and another damage failure. High chromium cast iron must have a relatively stable structure, good strength and toughness, excellent wear resistance, and corrosion resistance. In this study, the static corrosion performance of high-chromium cast iron was tested to study the effects of Mo and V elements addition and content changes on corrosion resistance and vanadium, molybdenum, and subcritical treatment processes on the microstructure and properties of high-chromium cast iron, in order to obtain better performance. Lower cost high chromium cast iron castings. As a wear-resistant part, high-chromium cast iron castings are widely used in wear and can cope with harsh working environments, but their excellent hardness conditions bring certain defects in toughness and at the same time lack good corrosion resistance, in mechanical extrusion., high-strength wear, chemical corrosion, and other harsh environments are prone to damage and failure. Therefore, high-chromium cast iron should have dual properties, not only high hardness but also suitable for mud, sand, chemicals, and other media corrosion and wear resistance.

Effect of quench-tempering and laser quenching on the microstructure and properties of high-chromium cast iron

In this paper, quench-tempering (QT) and laser quenching (LQ) treatments were performed on the high-chromium cast iron to obtain better microstructure and mechanical properties. The changes in microhardness, microstructure, retained austenite (RA) content, grain size, phase and elemental content of the QT and LQ samples were compared and analyzed. The results showed that the RA content of the untreated samples was 77.02% and the was 26.8 nm. The QT samples showed an increase in carbide dissolution, gradual rounding from sharp angles, transformation of austenite into martensite, reduction of RA content to 28.48%, average grain size (AGS) of 35.8 nm, increase in surface microhardness by 16.6%, and the friction coefficient was reduced by 6.9%. The LQ samples showed a large amount of fine martensite, daisy-like eutectic carbides and diffusely distributed secondary carbides, and the RA content was reduced to 17.72%, with an AGS of 29.9 nm. Compared with the QT samples, the LQ samples showed a 25.1% reduction in AGS, a 16.5% increase in surface microhardness, and a 9.7% decrease in friction coefficient, which was more wear resistant. However, the hard and brittle surface layer of the LQ samples tended to be a source of cracks during impact, resulting in a final reduction of 8.4% in impact toughness compared to the QT samples.

Effects of Si on the Microstructures and Mechanical Properties of High-Chromium Cast Iron

Effect of Si on the microstructures and mechanical properties of high-chromium cast iron was investigated. The eutectic carbides are refined greatly and a transformation of matrix from austenitic matrix to pearlite is observed with increase in Si content from 0.5 to 1.5 wt.%. The refinement of eutectic microstructure is attributed to the decrease in the eutectic temperature, while the transformation from austenite matrix to pearlite is associated with the increase in solubility of carbon in the matrix. In the pearlite matrix, two types of pearlite are observed: one with lamellar pearlite, distributing at the periphery, and the second one with granular pearlite at the center. The density of secondary carbides precipitated from the matrix increases greatly with addition of Si from 0.5 to 1.5 wt.%, which is associated with more carbon and chromium elements confined in the matrix in the alloy containing 1.5 wt.%. More rod-like particles are observed in the alloy containing 0.5 wt.% Si, while the morphology of secondary carbides of alloy containing 1.5 wt.% is granular. The mechanical properties are improved with a 7% increase in tensile strength from 586 to 626 MPa and impact toughness from 5.8 to 7.3 J cm−2.

Improving Wear Properties of High-Chromium Cast Iron by Manganese Alloying

High-chromium cast irons are widely needed by several industrial areas where wear is the dominant environment. They are used in mining, cement- and steel-making plants, and many others. Their microstructure consists of netted eutectic carbides embedded in an austenitic or martensitic matrix. The wear behaviour is mainly controlled by the carbides shape and also matrix type. Several scientific works try to improve the wear behaviour and to optimize the life service of this cast iron by using various techniques. In this work, we intend to study the effect of manganese content on the microstructure properties and wear behaviour of a 15 % chromium white cast iron used for ball mill production. The present work treats the wear behaviour, after heat treatment, of a manganese-alloyed high-chromium cast iron. A set of specimens were melted in an induction oven by varying the manganese content in the range 0–3 %. Heat-treated samples were analysed by optical microscopy, MEB (SEM) scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction and were wear tested by abrasion and friction. Increasing the manganese addition gave a structural evolution and a wear resistance improvement. The best wear behaviour is obtained with samples containing 3 % Mn.

INFLUENCE OF PHYSICAL AND HEAT PROCESSES ON THE STRUCTURE AND PROPERTIES OF HIGH-CHROMIUM CAST IRON DURING MACHINING

Purpose. Analysis of changes of high-chromium cast irons' structure and properties under the influence of physical and heat factors during mechanical machining. Methodology. The methodology of evaluation of the cutting tool's force and heat influence on the machined material has been developed and applied. Cast specimens underwent preliminary turning to obtain the diameter of 25 mm. The microsection was made on the end surface of the specimen with the length of 50 mm. Standard plates with sizes 10×10 mm made of VK8 according to the State Standard 19051-80 were used in the turning process. Findings. Force influence on the specimens made of highchromium cast iron caused strain hardening during machining. Temperature influence on the structure and properties of high-chromium cast iron during machining caused increase of the plasticity characteristics of the metallic base in the cutting area, fragmentation of the carbide phase and elimination of the strain hardening. During turning with cutting depth 0.8 mm only force influence of the cutting tool on the specimen took place. Carbide inclusions in the surface layer didn't undergo sufficient changes; at the same time the metallic base was strain-hardened to 1 100 HV50. As it was drawn away from the turning surface, the microhardness of the metallic base was decreasing and equaled to 500…520 HV50 at the distance of 1.2 mm from the turning surface. Strain hardening was not observed at the depth of more than 3mm. Cutting depth increase up to 1.5 mm caused simultaneous influence of force and heat factors. The temperature influence revealed in increasing of metallic base plasticity in the specimen's surface layers. Strain hardening of heated surface layers didn't occur. While drawing away from the cutting surface, the influence of the temperature factor decreased, when the influence of force factor remained the same. Due to the base plasticity decrease the strain hardening occurred. The metallic base strain was hardened to 490…520 HV50. The overall heating of the specimen caused the decrease of strain hardening depth to 0.4 mm. Originality. The methodology of change evaluation of high-chromium cast iron structure and properties under the influence of physical and heat factors during mechanical machining has been elaborated. Practical value. This methodology allows developing the recommendations for choices of highchromium cast iron machining modes and conditions.

Relation Between the Microstructure and Properties of High-Chromium Cast Iron

The effects of carbon and chromium and of the kind of heat treatment on the structure and properties of high-chromium cast iron (HCCI) is investigated. The methods of x-ray spectral and metallographic analysis are used to determine the mechanical properties and wear resistance of HCCI. It is shown that it is necessary to provide an austenitic structure of the metallic matrix by hardening from 1150°C in still air in order to obtain maximum strength, impact toughness, and wear resistance of the metal. A high-temperature hold (1150°C) provides rounding of the sharp edges of the segregating carbides, which promotes additional enhancement of the combination of the properties.

Change of surface properties of high-chromium cast iron under conditions of laser treatment and wear in a pellet stream

We investigate the influence of laser treatment on the formation of residual stresses relative to the changing structure-phase composition in the surface layers of high-chromium cast iron with 16% chromium. We show that appreciable tensile stresses are produced in the region of the laser action and that their distribution depends on whether the laser treatment was or was not accompanied by surface melting. The produced residual stresses are responsible for the formation of a large number of cracks. Preheating to 400°C lowers the level of the tensile residual stresses and prevents crack formation. A pellet stream acting on the surface produces cold-work hardening layers in which the tensile stresses change into compressive ones. The depth, hardness, and magnitude of the compressive residual stresses depend on the method used to work harden the cast iron and on the angle of attack of the pellet as it acts on the surface.

Effect of laser and heat treatment on the structure and properties of high-chromium cast iron

The authors investigate the effect of continuous radiation of a CO/sub 2/ laser in combination with standard heat treatment on the structure, phase composition, and properties of the wear-resistant high chromium cast iron IChKh16NMFTL. To compare the results of the effect of laser and heat treatment, the authors subjected specimens after quenching at 900/sup 0/C in oil together with laser treatment also to additional heta treatment: normalization, normalization with subsequent tempering at 250/sup 0/C 3 h, tempering along at 250 and 550/sup 0/C 3 h. Metallographic analysis was carried out with microscopes ''EPITYP-2'' and NUM-1, x-ray diffraction analysis on an installation URS-50IM in chromium K /SUB alpha/ radiation. It was established that in laser treatment with preliminary heating, the temperature at which cracks begin to appear depends on the direction in which the beam moves over the surface of the specimens. Thus, as a result of the investigations, it was established that hardening of wear-resistant cast iron IChKh16NMFTL is attained by the precipitation of disperse carbides (Cr, Fe)/sub 7/C/sub 3/ from the martensitic matrix.

Effect of heat treatment on the properties of high-chromium cast iron

1. Austenite in high-chromium cast irons is stable up to 500°. At higher temperatures the austenite begins to decompose, causing changes in the hardness, wear resistance, and mechanical properties. 2. The resistance of high-chromium cast iron to hydroabrasive wear is minimal in the cast condition and in the annealed condition. 3. To improve the machinability the alloys should be annealed at 800–900°, which lowers the hardness to HRC 32-35. 4. The resistance to hydroabrasive wear is highest after normalization at 1100°.