XRD Investigation on Heat Treatment of High Chrome White Cast Irons

Ngqase, Mbulelo; Pan, Xiaowei

doi:10.1088/1742-6596/1495/1/012022

Cited by 3 publications

(2 citation statements)

References 12 publications

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“…Heat treatment has been applied to HCCI to manipulate the microstructure and properties particularly hardness and wear [17,18]. The morphology and crystallographic properties of constituent phases, proportion of martensite, retained austenite and carbides are all the important factors influenced by heat treatment [17][18][19][20]. In this study, the microstructure of the HCCI alloys got refined after quenching.…”

Section: Discussionmentioning

confidence: 99%

On the influence of compositional variations in high chrome cast iron: an assessment of microstructure and mechanical behaviour

Nelwalani,

van der Merwe,

Munyangane

et al. 2024

Manufacturing Rev.

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In this study, the influence of compositional variation on the microstructure and properties of high chrome cast iron produced in jobbing foundries was evaluated. The aim was to determine whether compositional analysis alone is sufficient for qualifying acceptable high chrome cast iron components made in jobbing foundries. The compositions of the melts were analysed using optical emission spectroscopy. They were then compared with targeted compositions for commercially acceptable high chrome cast iron components. Equilibrium phases and phase transition temperatures of the different high chrome cast iron were calculated using the measured compositions as input on Thermo-Calc. Thermal analyses were also carried out to obtain the cooling profiles of each melt using ATAS MetStar software. The predictions from Thermo-Calc and ATAS Metster thermal analyses were then compared with experimentally determined optical and scanning electron images of the alloys. Hardness, fracture toughness, and wear resistance were determined both in the as-cast and heat-treated conditions. The results showed that even slight compositional variations significantly influence the microstructure and mechanical properties of high chrome cast iron, even when the compositions fall within the targeted compositional range typically accepted for industrial applications. Therefore, the study suggests that using compositional analysis alone is not sufficient for accepting high-quality high chrome cast iron components for industrial applications.

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Section: Discussionmentioning

confidence: 99%

On the influence of compositional variations in high chrome cast iron: an assessment of microstructure and mechanical behaviour

Nelwalani,

van der Merwe,

Munyangane

et al. 2024

Manufacturing Rev.

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show abstract

“…High chromium cast iron represents the third generation of wear-resistant materials, succeeding conventional white cast iron and nickel hard cast iron. Its remarkable attributes include exceptional wear resistance, elevated temperature endurance, and corrosion resilience, widely used in wear-resistant rollers, wear-resistant lining plates, slurry pumps and aerospace [1][2][3]. The heightened carbon and chromium content within hypereutectic high chromium cast iron results in a substantial augmentation of carbide quantities in comparison to conventional hypoeutectic high chromium cast iron.…”

Section: Introductionmentioning

confidence: 99%

Effect of tempering temperature on microstructure and properties of low silicon hypereutectic high chromium cast iron

Gu,

Liu,

et al. 2024

Materialwissenschaft Werkst

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High‐chromium cast iron is a good wear‐resistant material. Its heat treatment regime has an important influence on the evolution of its microstructure and properties. This study investigates the microstructural attributes and properties of Fe–4.0 C–35.0Cr–0.5Si (wt.%) low‐silicon hypereutectic high‐chromium cast iron subsequent to quenching at 1050 °C, followed by tempering at diverse temperatures. The microstructure was examined using optical microscopy, scanning electron microscopy, and X‐ray diffractometry across varied tempering conditions. Furthermore, microhardness and wear resistance were conducted via a microhardness tester and a wear testing machine. The results show that the quenching heat treatment promotes the transformation of the matrix from austenite to martensite, while also promoting the precipitation of secondary carbides of M23C6‐type. The subsequent tempering heat treatment engenders transformations involving retained austenite to martensite, amplifies the precipitation and enlargement of secondary carbides, and induces martensite decomposition. As the tempering temperature increases, primary and eutectic carbides exhibit minimal changes, while the secondary carbide morphology evolves from granular to reticular. The matrix composition predominantly comprises martensite, interspersed with a minor fraction of austenite. It is worth noting that the alloy has the highest hardness and wear resistance after quenching at 1050 °C and then tempering at 400 °C.

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Exploring residual stress analysis in the machining of hypoeutectic high chromium white cast iron alloys through the hole-drilling method

Ngqase,

Nheta,

Madzivhandila

et al. 2024

Eng. Res. Express

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High chromium white cast irons (HCWCIs), ASTM A352, Type A and Class III, i.e., 25%Cr iron in as-cast condition consists of proeutectic austenite (γ-Fe), transformed martensite (α-Fe) and discontinuous Cr-rich, i.e., M7C3/(Cr,Fe)7C3 type of carbides, which are hard and brittle in nature. Fully annealed thermal treatment was performed to improve iron’s machinability leading to fully pearlitic matrix with minor retained γ-Fe content. Eutectic (Cr,Fe)7C3 type of carbides are not affected by heat treatment processes. Resulting from corresponding manufacturing process, the magnitude and distribution of residual stresses (RSs) in as-cast and after machining were measured using hole-drilling method (HDM), as they are known to be harmful to corrosion and fatigue resistance. Furthermore, general metallurgical material characterisation was performed in as-cast and heat-treated conditions. As a result, this study revealed hardness variation, 547 and 555BHN in as-cast as compared to 327BHN in heat-treated condition. Furnace and actual cast component chemical analysis revealed a slight variation, especially between carbon (C) and chromium (Cr). Furthermore, eutectic type of carbides and precipitated secondary, i.e., (Cr,Fe)23C6 type of carbides within fully pearlitic matrix with minor amounts of retained γ-Fe were detected within the dominant matrix, i.e., pearlitic matrix in as-annealed condition. Detected magnitude and distributions of RSs on heat-treated sample resulted in higher tensile stresses in the surface and compressive in the interior as compared to sample in as-cast condition. Thus, this study was successfully in measuring RSs in as-cast and upon machining of hypoeutectic irons of HCWCI alloys using HDM.

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XRD Investigation on Heat Treatment of High Chrome White Cast Irons

Cited by 3 publications

References 12 publications

On the influence of compositional variations in high chrome cast iron: an assessment of microstructure and mechanical behaviour

On the influence of compositional variations in high chrome cast iron: an assessment of microstructure and mechanical behaviour

Effect of tempering temperature on microstructure and properties of low silicon hypereutectic high chromium cast iron

Exploring residual stress analysis in the machining of hypoeutectic high chromium white cast iron alloys through the hole-drilling method

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