Effect of retained austenite on the fatigue behavior of modified bainitic 100Cr6 steels considering local phase transformation

Ostermayer, Pascal; Allam, Tarek; Shen, Xiao; Song, Wenwen; Burkart, K.; Blinn, Bastian; Clausen, B.; Bleck, Wolfgang; Beck, Tilmann

doi:10.1016/j.msea.2023.145204

Cited by 6 publications

(3 citation statements)

References 19 publications

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“…In addition to the above-mentioned issues regarding the heat-treatment route of bearing steels, a key factor is the amount of retained austenite (RA) within the matrix [20][21][22]. Based on the specific needs of each application, RA may be required to enhance rolling contact fatigue performance, particularly in contaminated lubricating conditions [3,7,23,24]. Conversely, it may be avoided if dimensional stability is crucial, i.e., where bearings operate for extended durations at elevated temperatures [21].…”

Section: Introductionmentioning

confidence: 99%

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An Industrial-Scale Study of the Hardness and Microstructural Effects of Isothermal Heat Treatment Parameters on EN 100CrMo7 Bearing Steel

Fortini,

Bertarelli,

Cassola

et al. 2024

Applied Sciences

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The 100CrMo7, commonly employed for bearings in rotating machinery, relies on precise heat treatment parameters to ensure an optimal microstructure and, in turn, mechanical properties. Typically, an austenitizing treatment, followed by rapid cooling in a salt bath for martempering or austempering, is crucial in achieving the desired microstructure and hardness. The present industrial-scale study involved a comparative analysis between martempering and austempering routes regarding the hardness and microstructure evolution of EN 100CrMo7 large-size rings. The investigation delves into the effects of austempering temperatures, holding times, and austenitizing temperature. Furthermore, the role of tempering in reducing the amount of retained austenite was also considered. The results indicate that martempering yielded the highest hardness values while austempering exhibited a decrease in hardness at the center of the rings, though a lower amount of retained austenite (in the range of 3.0–4.9 vol.%) was detected in comparison with martempering. In addition, a 850 °C austenitizing temperature reduced the hardness by 16% in the center of the rings and promoted a high content of upper bainite, thus suggesting its inefficacy for the involved large-size rings. In contrast, a 880 °C austenitizing temperature maintained consistently high HRC values across the ring’s height. Lastly, the analysis highlighted that the cooling rate played a more crucial role than the austempering holding time. Such industrial-scale investigations performed on real components improve the knowledge and control of heat treatment parameters in comparison with the nominal guidelines provided by steel suppliers. These outcomes offer insights for optimizing industrial heat treatment parameters, with practical implications for enhancing steel bearings’ microstructural and mechanical performance and lifespan.

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Section: Introductionmentioning

confidence: 99%

“…Conversely, it may be avoided if dimensional stability is crucial, i.e., where bearings operate for extended durations at elevated temperatures [21]. Indeed, high RA contents decrease the ultimate strength of the material [23,25,26] and lead to a smaller dimensional stability due to phase transformation [22].…”

Section: Introductionmentioning

confidence: 99%

An Industrial-Scale Study of the Hardness and Microstructural Effects of Isothermal Heat Treatment Parameters on EN 100CrMo7 Bearing Steel

Fortini,

Bertarelli,

Cassola

et al. 2024

Applied Sciences

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“…In aerospace, automotive, agricultural and marine industries, DeepCryoTreat has been widely used as a supplemental and permanent treatment after ConHeatTreat to improve the hardness and wear resistance of steels because DeepCryoTreat eliminates retained austenite and precipitates fine secondary carbides [8][9][10][11]. Since transforming retained austenite in steel into martensite reduces its working lifespan via brittle failure such as micro-cracking, elimination of retained austenite by DeepCryoTreat can lessen its brittle failure [12,13]. Akhbarizadeh et al [14] reported that DeepCryoTreat-D6 tool steel had the better tribological performance than quenched and tempered steel.…”

Section: Introductionmentioning

confidence: 99%

Effects of Deep Cryogenic Treatment on Friction and Wear of EN24 Steel Against Alumina Under Dry and Lubrication Conditions

Win Khun,

Liu,

Senthilkumar

et al. 2024

Tribol. Ind.

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As-received (AsRec) EN24 steel was treated with conventional heat treatment (ConHeatTreat) without tempering followed by deep cryogenic treatment (DeepCryoTreat) as a supplemental treatment to study its tribological behaviour against alumina without or with mineral oil (MO) under different normal loads of 1 N and 5 N. The ConHeatTreat of the AsRec-EN24 obtained an 218.5% improvement in its hardness as the supplemental DeepCryoTreat of the ConHeatTreat-EN24 resulted in a 11.7% further improvement in its hardness. As a result, the ConHeatTreat-EN24 had the 67.5% and 56.3% lower wear volumes for 1 N and 5 N under dry condition and the 53.6% lower wear volume for 5 N under MO lubrication condition compared to those of the AsRec-EN24, respectively. The DeepCryoTreat-EN24 had the 11.5% and 39.7% lower wear volumes for 1 N and 5 N under dry condition and the unmeasurable wear volume for 5 N under MO lubrication condition compared to those of the ConHeatTreat-EN24, respectively. It could be concluded that the supplemental DeepCryoTreat further improved the hardness and thereby the abrasive wear resistance of the ConHeatTreat-EN24 under both dry and lubrication conditions.

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Phase transitions in medium-Mn alloy: thermodynamic simulation and experimental verification

Skowronek,

Kozłowska

2024

J Therm Anal Calorim

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The present work explores a design process of new medium-Mn alloy for forgings and its heat treatment optimization by thermodynamic simulations and experimental approach. The selection of specific chemical composition was performed on the basis of thermodynamic simulation for alloys with different additions of Mn and Al. The aim was to design an alloy allowing for production of at least 25% retained austenite in an intercritical annealing process, without deteriorating technological properties and economic indicators. Next simulations of intercritical annealing in a temperature range between 600 and 1000 °C, and their experimental verification were performed. For the thermodynamical simulations of different chemical compositions of steel and its intercritical annealing in a wide temperature range the JMatPro software was used. To verify the characteristic temperatures of steel such as Ac1, Ac3 and Ms, and for experimental investigation of intercritical annealing in a temperature range from 660 to 740 °C dilatometry was used. Obtained microstructures were characterized by means of X-ray diffraction and scanning electron microscopy. It was observed that with an initial increase in soaking temperature a fraction of retained austenite increases; however, its stability decreases, which leads to formation of large martensite fraction during cooling after soaking at high temperatures. The results of thermodynamic simulations and experimental tests showed the moderate agreement. Large differences were revealed for Ac1, Ms temperatures and the amount of retained austenite obtained at a given annealing temperature. The results clearly indicate that at the moment of software development and available databases for novel medium-Mn steels, simulations of their heat treatment can only be used to estimate results and be a guide for experimental research. However, they cannot be used to optimize heat treatment.

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Effect of retained austenite on the fatigue behavior of modified bainitic 100Cr6 steels considering local phase transformation

Cited by 6 publications

References 19 publications

An Industrial-Scale Study of the Hardness and Microstructural Effects of Isothermal Heat Treatment Parameters on EN 100CrMo7 Bearing Steel

An Industrial-Scale Study of the Hardness and Microstructural Effects of Isothermal Heat Treatment Parameters on EN 100CrMo7 Bearing Steel

Effects of Deep Cryogenic Treatment on Friction and Wear of EN24 Steel Against Alumina Under Dry and Lubrication Conditions

Phase transitions in medium-Mn alloy: thermodynamic simulation and experimental verification

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