Editorial

4 pages, 189 KiB

Open AccessEditorial

by Annalisa Fortini and Chiara Soffritti

Metals 2023, 13(5), 980; https://0-doi-org.brum.beds.ac.uk/10.3390/met13050980 - 19 May 2023

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Cast irons are widely used in industry due to their excellent castability, allowing for the production of near-net shape components with complex geometries without the need for additional forging or machining processes [...] Full article

(This article belongs to the Special Issue Recent Advances in Cast Irons)

Research

Jump to: Editorial, Review

12 pages, 13558 KiB

Open AccessArticle

Surface Evolution of Vermicular Cast Iron in High Frequent Cyclic Plasma and Different Facial Cooling Airflows

by Lei Liu, Ke Zhao, Haijun Zhang, Chengwei Tang, Qinxin Han, Jiajia Chen, Dong Tao and Zhong Yang

Metals 2023, 13(3), 577; https://0-doi-org.brum.beds.ac.uk/10.3390/met13030577 - 13 Mar 2023

Cited by 2 | Viewed by 1077

Abstract

The surface evolution of vermicular cast iron in a high frequent cyclic plasma and facial cooling airflow was studied to understand the behavior and mechanism in different cooling conditions under a unique thermal shock environment. Results indicated that both the mass and linear [...] Read more.

The surface evolution of vermicular cast iron in a high frequent cyclic plasma and facial cooling airflow was studied to understand the behavior and mechanism in different cooling conditions under a unique thermal shock environment. Results indicated that both the mass and linear loss presented titled inverted V-shaped relationships with the flux of the cooling airflow, while the change in roughness decreased continuously. As the cooling airflow rose, the eroded zone was reduced, the iron oxides lessened, and fluctuation of the surface temperature weakened. In combination with the thermodynamic calculations and thermal analysis, it was confirmed that the oxidation and mechanical erosion had contrary tendencies with the rising flux in the facial cooling airflow. The transformation of the dominant factor from oxidation to peeling off by thermal stress and scouring resulted in the evolution of mass and thickness. The surface oxides dominated the change in the roughness. Full article

(This article belongs to the Special Issue Recent Advances in Cast Irons)

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14 pages, 5460 KiB

Open AccessArticle

Wear Behavior of Nb Alloyed Gray Cast Iron for Automotive Brake Disc Application

by Pietro Tonolini, Lorenzo Montesano, Annalisa Pola, Gianpietro Bontempi and Marcello Gelfi

Metals 2023, 13(2), 365; https://0-doi-org.brum.beds.ac.uk/10.3390/met13020365 - 11 Feb 2023

Cited by 2 | Viewed by 1695

Abstract

Gray cast iron (GCI) with a pearlitic matrix and type-A graphite remains the most widely used material in the manufacturing of brake discs. To reduce the environmental impact of disc wear during braking, alternative materials and/or compositions to the standard ones are being [...] Read more.

Gray cast iron (GCI) with a pearlitic matrix and type-A graphite remains the most widely used material in the manufacturing of brake discs. To reduce the environmental impact of disc wear during braking, alternative materials and/or compositions to the standard ones are being studied. In this study, the effect of variation in niobium content (0–0.7 wt%) on microstructure and wear behavior of samples machined from brake discs made of hypoeutectic gray cast iron was investigated. The wear behavior of GCI was examined through pin-on-disc (PoD) wear tests using low-metallic-friction material discs as the counterparts. Microstructural analyses and hardness measurements were also conducted to evaluate the effect of Nb addition on the morphology of graphite, eutectic cells, and distribution of carbides. In addition, the wear mechanisms of different samples were evaluated using scanning electron microscope analysis. The results revealed that adding 0.3% of Nb promotes the highest wear resistance of the alloys. Full article

(This article belongs to the Special Issue Recent Advances in Cast Irons)

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19 pages, 3695 KiB

Open AccessFeature PaperArticle

Performance Evaluation of Austempered Ductile Iron Camshaft Low Alloyed with Vanadium on an Electric Spin Rig Test

by Alejandro Cruz Ramírez, Eduardo Colin García, Jaime Téllez Ramírez and Antonio Magaña Hernández

Metals 2023, 13(2), 198; https://0-doi-org.brum.beds.ac.uk/10.3390/met13020198 - 18 Jan 2023

Cited by 2 | Viewed by 2136

Abstract

Arbomex S.A. de C. V. is one of the largest worldwide manufacturers of ductile cast iron camshafts, produced by means of the phenolic urethane no-bake sand mold casting method and cold box by stack molding technology. As a result of the development of [...] Read more.

Arbomex S.A. de C. V. is one of the largest worldwide manufacturers of ductile cast iron camshafts, produced by means of the phenolic urethane no-bake sand mold casting method and cold box by stack molding technology. As a result of the development of high-strength ADIs, low alloyed with vanadium, for camshaft manufacturing, previous results were published on the as-cast process and the austempering heat treatments applied to the camshafts. In the present work, camshafts of ADIs, low alloyed with 0.2 and 0.3 wt.% V, were produced at austempering temperatures of 265 and 305 °C. The performance of the new camshafts was evaluated by wear testing to ensure the function and durability of the camshafts by means of the block-on-ring wear test and a valve train system to evaluate the volume loss of material removed and the geometrical changes of the camshaft, respectively. The ADIs heat treated to 265 °C showed a microstructure constituted of fine ausferrite that aided in obtaining the highest wear resistance in the block-on ring wear test. No wear or pitting evidence was detected on the camshaft lobes and roller surfaces after the OEM test protocol during the electric spin ring test at low and high conditions for the ADI alloyed with 0.2 wt.% V heat treated at 265 °C. Full article

(This article belongs to the Special Issue Recent Advances in Cast Irons)

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24 pages, 10400 KiB

Open AccessArticle

On Ausferrite Produced in Thin Sections: Stability Assessment through Round and Flat Tensile Specimen Testing

by Giuliano Angella, Riccardo Donnini, Dario Ripamonti, Franco Bonollo, Bogdan Cygan and Marcin Gorny

Metals 2023, 13(1), 105; https://0-doi-org.brum.beds.ac.uk/10.3390/met13010105 - 04 Jan 2023

Cited by 2 | Viewed by 1179

Abstract

Ductile irons were produced into different casting wall sections, that is, 25 mm, 5 mm and 3 mm. The alloys were then austenitized with the same conditions at 875 °C for 2 h and austempered for three different combinations of temperatures and times: [...] Read more.

Ductile irons were produced into different casting wall sections, that is, 25 mm, 5 mm and 3 mm. The alloys were then austenitized with the same conditions at 875 °C for 2 h and austempered for three different combinations of temperatures and times: 250 °C for 6 h, 310 °C for 3 h and 380 °C for 1 h. The aim of the investigation was to study the ausferrite stability of austempered ductile irons with three different nominal contents of nickel produced in thin sections through tensile testing. So, strain hardening analysis of tensile flow curves was carried out since it has been found to be a reliable support to ductility analysis in assessing the optimal austempering conditions. Because of different wall sections, round and flat tensile specimens with geometries complying with ASTM E8/E8M-11 were tested. Austempered ductile irons from 5 and 3 mm wall sections were tested through flat geometry specimens only, while 25 mm wall sections were tested through both round and flat geometries. Though the ausferrite was affected by Ni content and the graphite morphology was improved with reduced thin sections, the ausferrite stability and the tensile mechanical behavior were insensitive to Ni content and section thickness below 25 mm. Furthermore, it resulted that the tensile plastic behavior was sensitive to the specimen geometry in a consistent way, increasing the instability of ausferrite and indicating that a proper analysis and comparison of tensile properties of austempered ductile irons must take into account the tensile specimen geometry. Full article

(This article belongs to the Special Issue Recent Advances in Cast Irons)

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26 pages, 111396 KiB

Open AccessArticle

Strain-Controlled Fatigue Behavior of a Nodular Cast Iron in Real Off-Highway Axles: Effects of Casting Skin and Strain Ratio

by Federico Scacco, Alberto Campagnolo, Mattia Franceschi and Giovanni Meneghetti

Metals 2022, 12(3), 426; https://0-doi-org.brum.beds.ac.uk/10.3390/met12030426 - 28 Feb 2022

Cited by 5 | Viewed by 2589

Abstract

Nodular cast irons are widely adopted in off-highway vehicles, since they allow to obtain components with complex shapes as well as good mechanical properties. However, the fatigue strength of such components is a major issue, which is typically addressed by adopting the strain-life [...] Read more.

Nodular cast irons are widely adopted in off-highway vehicles, since they allow to obtain components with complex shapes as well as good mechanical properties. However, the fatigue strength of such components is a major issue, which is typically addressed by adopting the strain-life approach, since it considers the local strains at stress concentrators where fatigue cracks are prone to initiate. In the fatigue design of off-highway components, the detrimental effect of casting skin, due to both surface and subsurface features, must be accounted for in all cases where machining is not needed. Moreover, the local strain ratio at stress raisers can be different from the nominal one due to forward plasticity. In this paper, static tensile as well as strain-controlled fatigue tests have been executed on specimens taken from real EN-GJS-450-10 off-highway axles. Static tensile tests have been performed on specimens with machined surfaces, while fatigue tests at a strain ratio equal to −1 have been carried out on specimens with surfaces in both machined and as-cast conditions. In addition, machined specimens have been tested at strain ratios equal to 0.1 and 0.5 to investigate the material sensitivity to the mean strain. Finally, the high-cycle downgrading effect of the casting skin has been evaluated, and experimental data of machined specimens tested at different strain ratios have been summarized by using the Smith–Watson–Topper expression. Full article

(This article belongs to the Special Issue Recent Advances in Cast Irons)

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11 pages, 45007 KiB

Open AccessArticle

Microstructural Evolution as a Function of Increasing Aluminum Content in Novel Lightweight Cast Irons

by Alejandro Obregon, Jon Mikel Sanchez, David Eguizabal, Jose Carlos Garcia, Gurutze Arruebarrena, Iñaki Hurtado, Ion Quintana and Patxi Rodriguez

Metals 2021, 11(10), 1646; https://0-doi-org.brum.beds.ac.uk/10.3390/met11101646 - 18 Oct 2021

Cited by 1 | Viewed by 1697

Abstract

In the context of the development of new lightweight materials, Al-alloyed cast irons have a great potential for reducing the weight of the different part of the vehicles in the transport industry. The correlation of the amount of Al and its effect in [...] Read more.

In the context of the development of new lightweight materials, Al-alloyed cast irons have a great potential for reducing the weight of the different part of the vehicles in the transport industry. The correlation of the amount of Al and its effect in the microstructure of cast irons is not completely well established as it is affected by many factors such as chemical composition, cooling rate, etc. In this work, four novel lightweight cast irons were developed with different amounts of Al (from 0 wt. % to 15 wt. %). The alloys were manufactured by an easily scalable and affordable gravity casting process in an induction furnace, and casted in a resin-bonded sand mold. The microstructural evolution as a function of increasing Al content by different microstructural characterization techniques was studied. The hardness of the cast irons was measured by the Vickers indentation test and correlated with the previously characterized microstructures. In general, the microstructural evolution shows that the perlite content decrease with the increment of wt. % of Al. The opposite occurs with the ferrite content. In the case of graphite, a slight increment occurs with 2 wt. % of Al, but a great decrease occurs until 15 wt. % of Al. The addition of Al promotes the stabilization of ferrite in the studied alloys. The hardness obtained varied from 235 HV and 363 HV in function of the Al content. The addition of Al increases the hardness of the studied cast irons, but not gradually. The alloy with the highest hardness is the alloy containing 7 wt. % Al, which is correlated with the formation of kappa-carbides and finer perlite. Full article

(This article belongs to the Special Issue Recent Advances in Cast Irons)

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16 pages, 4741 KiB

Open AccessArticle

Solidification Pattern of Si-Alloyed, Inoculated Ductile Cast Irons, Evaluated by Thermal Analysis

by Iuliana Stan, Denisa Anca, Stelian Stan and Iulian Riposan

Metals 2021, 11(5), 846; https://0-doi-org.brum.beds.ac.uk/10.3390/met11050846 - 20 May 2021

Cited by 6 | Viewed by 2237

Abstract

The solidification cooling curve itself as well as its first derivative, and related temperatures, reported to the calculated equilibrium temperatures in stable and metastable solidification systems, are used to predict the solidification characteristics of the cast iron. Silicon, as the most representative cast [...] Read more.

The solidification cooling curve itself as well as its first derivative, and related temperatures, reported to the calculated equilibrium temperatures in stable and metastable solidification systems, are used to predict the solidification characteristics of the cast iron. Silicon, as the most representative cast iron element, and inoculation, as graphitizing metallurgical treatment, have a major influence on the transition from the liquid to the solid state. Six experimental programs are performed, with Si content typically for non-alloyed (<3.0% Si), low (3.0–3.5% Si) and medium alloyed (4.5–5.5% Si) ductile cast irons, as Si-content increasing, and inoculation simultaneous effects. Silicon is an important influencing factor, but the base and minor elements also affect the equilibrium eutectic temperatures, much more in the Fe-C-Si-Xi stable system (15–20 °C) than in the metastable system (5–10 °C), comparing with their calculation based only on a Si effect (Fe-C-Si system). The highest positive effect of inoculation is visible in non-Si alloyed cast irons (2.5% Si): 9–15 °C for the eutectic reaction and 3 to 4 times increased at the end of solidification (37–47 °C). Increased Si content decreases inoculation power to 7–9 °C for low alloying grade (up to 3.5% Si), with the lowest contribution at more than 4.5% Si (0.3–2.0 °C). 2.5–3.5% Si ductile cast irons are more sensitive to high solidification undercooling, especially at the end of solidification (but with a higher efficiency of inoculation), compared to 4.5–5.5% Si ductile cast irons, at a lower undercooling level, and at lower inoculation contribution, as well. Full article

(This article belongs to the Special Issue Recent Advances in Cast Irons)

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12 pages, 85160 KiB

Open AccessFeature PaperArticle

Hardness Prediction in Quenched and Tempered Nodular Cast Iron Using the Hollomon-Jaffe Parameter

by Fidel Salas Vicente, Javier Carcel Carrasco, Raquel Fernández Antoni, Juan Carlos Ferrero Taberner and Manuel Pascual Guillamón

Metals 2021, 11(2), 297; https://0-doi-org.brum.beds.ac.uk/10.3390/met11020297 - 09 Feb 2021

Cited by 3 | Viewed by 2797

Abstract

The Hollomon-Jaffe parameter is usually used to stablish a equivalence between time and temperature in a tempering treatment, but not to predict the harness of the alloy after the treatment. In this paper this last possibility has been studied. A group of cast [...] Read more.

The Hollomon-Jaffe parameter is usually used to stablish a equivalence between time and temperature in a tempering treatment, but not to predict the harness of the alloy after the treatment. In this paper this last possibility has been studied. A group of cast iron samples was annealed and cooled at different rates in order to obtain samples with three different hardness values. These samples were tempered using different times and temperatures. The Hollomon-Jaffe parameter was calculated for each case and a relationship based on a logistic function between that parameter and the final hardness was stablished. This relationship was found to depend on the initial hardness and the lowest hardness achievable. Full article

(This article belongs to the Special Issue Recent Advances in Cast Irons)

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Review

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21 pages, 4452 KiB

Open AccessReview

Corrosion Wear of Hypereutectic High Chromium Cast Iron: A Review

by Liqiang Gong, Hanguang Fu and Xiaohui Zhi

Metals 2023, 13(2), 308; https://0-doi-org.brum.beds.ac.uk/10.3390/met13020308 - 02 Feb 2023

Cited by 8 | Viewed by 1789

Abstract

Hypereutectic High Chromium Cast Iron (HHCCI) is a new type of corrosion-wear-resistant material developed from ordinary high chromium cast iron by increasing the chromium and carbon content and is often used in abrasive environments where wear and corrosion interact. The corrosion wear resistance [...] Read more.

Hypereutectic High Chromium Cast Iron (HHCCI) is a new type of corrosion-wear-resistant material developed from ordinary high chromium cast iron by increasing the chromium and carbon content and is often used in abrasive environments where wear and corrosion interact. The corrosion wear resistance of the HHCCI is related to the number, size, shape and distribution of carbides and the microstructure of the matrix. This paper reviews the research progress in improving the corrosion wear resistance of HHCCI from various aspects such as primary carbide refinement, heat treatment, deep cooling treatment and alloying, etc. Among the methods of refining primary carbides are modification, semi-solid treatment and current pulse treatment. In addition, we also analyze the potential of Cr, V, Nb, Mo, Mn, W, Ni, Cu, Si, N and other alloying elements to improve the corrosion wear resistance of HHCCI. The mechanism for improving the corrosion wear resistance of HHCCI is also explored in depth and research contents worthy of attention are proposed to further improve the corrosion wear resistance of HHCCI. In the future, the author believes that modification + alloying + heat treatment is the most potential application method to improve the corrosion wear resistance of HHCCI. The corrosion wear resistance of HHCCI can be further improved by refining the primary carbide (such as adding rare earth, Ti and other modified elements) + heat treatment (with cryogenic treatment) to improve the strength + alloying (such as adding low-cost, high-potential alloy elements such as N and Si) to improve the corrosion wear resistance of the matrix. Full article

(This article belongs to the Special Issue Recent Advances in Cast Irons)

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