Quenching and partitioning heat treatment in ductile cast irons

Silva, Anderson José Saretta Tomaz da; Goldenstein, Hélio; Guesser, Wilson Luiz; Campos, Marcos Flávio de

doi:10.1590/1516-1439.220713

Cited by 15 publications

(11 citation statements)

References 10 publications

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“…The chemical composition was 3.47C-2.47Si-0.20Mn-0.38Cu (in wt.%) and the nodule count was above 400 nodules/mm 2 . The relatively low manganese content (0.20 wt.%) and high nodule count were intentionally employed, in order to minimize microsegregation, as described in previous work [4].…”

Section: Materials Characterisationmentioning

confidence: 99%

“…Recent research [4,5,6,7,8] has shown that the Q&P process when applied to ductile iron produces material with significantly higher tensile strength whilst retaining satisfactory ductility. The unique mechanical properties, when compared with several classes of ductile iron found in the literature Figure 1: Schematic diagrams of the Q&P process, which obtains ferrite/austenite/martensite microstructures from the decomposition of homogenous austenite.…”

Section: Introductionmentioning

confidence: 99%

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Effect of microstructure on fatigue behaviour of advanced high strength ductile cast iron produced by quenching and partitioning process

Melado

Nishikawa

Goldenstein

et al. 2017

International Journal of Fatigue

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The fatigue behaviour of high strength ductile cast iron produced by a quenching and partitioning process (Q&P) is evaluated. The Q&P process is receiving increased attention as a new way to produce ultra-high strength steels with multiphase microstructures composed of a martensite matrix and substantial amounts of carbon-stabilized retained austenite. Currently, the mechanical properties arising from applying the Q&P process in ductile cast irons have not been investigated. Thermal treatments consisted of heating the material to 880°C for a 2 hour soaking time followed by quenching in oil at 140°C and 170°C, intermediate temperatures between Ms and Mf allowing the formation of a controlled amount of athermal martensite. The material was reheated to 300°C and 375°C (the partition treatment) for different times between 15 and 120 minutes and subsequently air-cooled to room temperature. Microstructural evolution and carbon partitioning was investigated by in situ synchrotron X-ray diffraction. With a microstructure composed of tempered martensite, bainitic ferrite and carbon-enriched stabilized austenite, a new class of properties was obtained, with an enhanced strength when compared to ADI (austempered ductile iron) while still maintaining reasonable elongation. Fatigue testing was undertaken using polished plain bend bars (no stress concentration features) assessed under four-point bending. Uninterrupted tests at varying loads show that the higher partitioning temperature is beneficial for fatigue life. Fracture initiation sites are primarily from pores and a number of decohered graphite nodules. A strong influence of the microstructure on subsequent fatigue crack growth is observed from interrupted testing with replica records and SEM examination of tested samples, with cracks exhibiting significant tortuosity, at times even appearing to grow approximately parallel to the tensile axis. Using these results, the effects of the Q&P treatment, particularly the role of the partitioning time and temperature, on the fatigue properties of ductile cast iron are assessed.

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Section: Materials Characterisationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of microstructure on fatigue behaviour of advanced high strength ductile cast iron produced by quenching and partitioning process

Melado

Nishikawa

Goldenstein

et al. 2017

International Journal of Fatigue

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“…All the samples were cut at the bottom of Y block. The samples were austenitized at 900 for 2 hours [14] and then quenched into cylinder oil at 160 for 2 minutes. After that, the specimens were quickly poured into nitrate furnace with 300 to carry out partitioning process.…”

Section: Methodsmentioning

confidence: 99%

“…Since the matrix of DCIs has similar chemical composition and microstructure to the steels, some methods of heat treatment methods used in the steels can also be used in DCIs to change its matrix microstructure and then its properties. So far, the properties of DCIs have already improved by several heat treatment methods used in the steel, such as electropulsing annealing [9], quenching and tempering [10], thermomechanically treatment [11], austempering [12][13], and quenching and partitioning [14]. Among them, quenching and partitioning process is an important heat treatment method for steel and has already been discussed in details [15].…”

Section: Introductionmentioning

confidence: 99%

Effect of Quenching and Partitioning Heat Treatment on Ductile Cast Irons

Zhao

Wang²,

Hang

et al. 2016

MATEC Web Conf.

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Abstract. In this study, the ductile cast irons were prepared by the melting process and then carried out the quenching and partitioning heat treatment. The microstructures were observed by both an optical microscopy and a field emission scanning electron microscope and the tensile strengths were measured by a uniaxial tensile tester. The effect of partitioning time on the microstructures and the tensile strength were investigated. The results showed that the matrix of as-cast samples contain about 26% ferrite and 74% pearlite and the microstructure quenched without partitioning consisted of a mixture of graphite nodules plus lath martensite plus retained austenite. With the increase of the partitioning time, the retained austenite became stable and could transform into lower bainite or carbide gradually, which gave rise to the fact that the tensile strength changed nonlinearly and reached a maximum at the partitioning time about 120 minutes.

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“…However, employment of large fractions of alloying elements increases the production costs and may imply processing difficulties due to, for example, development of segregation bands. This is even more critical when considering the Q&P applied to cast products, such as cast iron, where the microsegregation formed during solidification is not mitigated by further thermomechanical processing [12].…”

Section: Introductionmentioning

confidence: 99%

Influence of bainite reaction on the kinetics of carbon redistribution during the Quenching and Partitioning process

et al. 2018

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In the present study the microstructural evolution and kinetics of carbon redistribution during the partitioning step of the Quenching and Partitioning process are investigated by means of a modeling approach that simultaneously considers the martensite-austenite carbon partitioning and the decomposition of austenite into bainitic ferrite. The development of the phase fractions, interface position, and carbon compositions are analyzed for two different binary Fe-C alloys with distinct initial carbon compositions and simulation geometries. The composition dependence of carbon diffusivity in austenite is taken into account for solving the diffusion field equations. Simulations indicate that kinetics of carbon partitioning from martensite to austenite is controlled by carbon diffusion in martensite and it is little affected by simultaneous occurrence of bainite reaction. On the other hand martensiteaustenite carbon partitioning strongly influences the bainite reaction by inhibiting the growth of bainitic ferrite.

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Quenching and partitioning heat treatment in ductile cast irons

Cited by 15 publications

References 10 publications

Effect of microstructure on fatigue behaviour of advanced high strength ductile cast iron produced by quenching and partitioning process

Effect of microstructure on fatigue behaviour of advanced high strength ductile cast iron produced by quenching and partitioning process

Effect of Quenching and Partitioning Heat Treatment on Ductile Cast Irons

Influence of bainite reaction on the kinetics of carbon redistribution during the Quenching and Partitioning process

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