Phase evolution and carbon redistribution during continuous tempering of martensite studied with high resolution techniques

Vieweg, Annika; Povoden-Karadeniz, Erwin; Ressel, Gerald; Prevedel, Petri; Wójcik, Tomasz; Martín, Francisca Méndez; Stark, Andreas; Kečkéš, Jozef; Kozeschnik, Ernst

doi:10.1016/j.matdes.2017.09.065

Cited by 30 publications

(16 citation statements)

References 37 publications

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“…This temperature range was also found in Reference [ 2 , 24 ] for a steel with similar composition as SAE 52100. For the medium carbon steel SAE 4150 (EN 50CrMo4), the authors of Reference [ 22 ] found a higher temperature range between approximately 350 and 400 °C for the decomposition of retained austenite, which could not be supported for the very similar SAE 4140 in this study. The hot-working tool steel SAE H13 contains a similar carbon content as the SAE 4140, which results in the same initial amount of retained austenite of approximately 5%.…”

Section: Discussioncontrasting

confidence: 91%

“…Between approximately 80–200 °C, a dip in the dilatation derivative can be found. Usually, tempering stage 1, the precipitation of

-carbides, is found to occur in this temperature regime [ 2 , 3 , 21 ], whereas a recent paper [ 22 ] claims that this dip is due to a carbon redistribution during tempering. From 240 to 400 °C, a second dip is visible, which is much more pronounced compared to the first one.…”

Section: Results and Interpretationmentioning

confidence: 99%

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Comparative Study of the Tempering Behavior of Different Martensitic Steels by Means of In-Situ Diffractometry and Dilatometry

et al. 2020

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Martensitic steels are tempered to increase the toughness of the metastable martensite, which is brittle in the as-quenched state, and to achieve a more stable microstructure. During the tempering of steels, several particular overlapping effects can arise. Classical dilatometric investigations can only detect effects by monitoring the integral length change of the sample. Additional in-situ diffractometry allowed a differentiation of the individual effects such as transformation of retained austenite and formation of cementite during tempering. Additionally, the lattice parameters of martensite and therefrom the tetragonality was analyzed. Two low-alloy steels with carbon contents of 0.4 and 1.0 wt.% and a high-alloy 5Cr-1Mo-steel with 0.4 wt.% carbon were investigated by dilatometry and in-situ diffractometry. In this paper, microstructural effects during tempering of the investigated steels are discussed by a comparative study of dilatometric and diffractometric experiments. The influence of the chemical composition on the tempering behavior is illustrated by comparing the determined effects of the three steels. The kinetics of tempering is similar for the low-alloy steels and shifted to much higher temperatures for the high-alloy steel. During tempering, the tetragonality of martensite in the steel with 1.0 wt% carbon shifts towards a low carbon behavior, as in the steels with 0.4 wt.% carbon.

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Section: Discussioncontrasting

confidence: 91%

“…Between approximately 80–200 °C, a dip in the dilatation derivative can be found. Usually, tempering stage 1, the precipitation of

Section: Results and Interpretationmentioning

confidence: 99%

Comparative Study of the Tempering Behavior of Different Martensitic Steels by Means of In-Situ Diffractometry and Dilatometry

et al. 2020

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“…A sample material for the heating experiments of the steel grade 50CrMo4 was used with the chemical composition given in Table 1 [9]. In Figure 4, the specific heat, mass density, electrical conductivity, and relative magnetic permeability are shown compared to the temperature.…”

Section: Materials Propertiesmentioning

confidence: 99%

Inverse Model for the Control of Induction Heat Treatments

et al. 2019

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In this work, we present and test an approach based on an inverse model applicable to the control of induction heat treatments. The inverse model is comprised of a simplified analytical forward model trained with experiments to predict and control the temperature of a location in a cylindrical sample starting from any initial temperature. We solve the coupled nonlinear electromagnetic-thermal problem, which contains a temperature dependent parameter α to correct the electromagnetic field on the surface of a cylinder, and as a result effectively the modeled temperature elsewhere in the sample. A calibrated model to the measurement data applied with the process information such as the operating power level, current, frequency, and temperature provides the basic ingredients to construct an inverse model toolbox, which finally enables us to conduct experiments with more specific goals. The input set values of the power supply, i.e., the power levels in the test rig control system, are determined within an iterative framework to reach specific target temperatures in prescribed times. We verify the concept on an induction heating test rig and provide two examples to illustrate the approach. The advantages of the method lie in its simplicity, computationally cost effectiveness and independence of a prior knowledge of the internal structure of power supplies.

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“…Consequently, higher temperatures are needed to enhance the diffusion rate [18,19] and therefore enable an intended quantity of carbon formation. Detailed evaluation of the processes during tempering was done in a different study by the authors [20]. In this work, heat treating parameters were adapted in order to achieve uniform hardness values (∼400 HV10) for different heating rates to get a reasonable comparison of the Charpy impact values.…”

Section: Effect Of Heating Rates On Precipitation Kinetics During Temmentioning

confidence: 99%

Comparing fast inductive tempering and conventional tempering: Effects on microstructure and mechanical properties

Vieweg

Ressel

Raninger

et al. 2018

Metall. Res. Technol.

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Induction heating processes are of rising interest within the heat treating industry. Using inductive tempering, a lot of production time can be saved compared to a conventional tempering treatment. However, it is not completely understood how fast inductive processes influence the quenched and tempered microstructure and the corresponding mechanical properties. The aim of this work is to highlight differences between inductive and conventional tempering processes and to suggest a possible processing route which results in optimized microstructures, as well as desirable mechanical properties. Therefore, the present work evaluates the influencing factors of high heating rates to tempering temperatures on the microstructure as well as hardness and Charpy impact energy. To this end, after quenching a 50CrMo4 steel three different induction tempering processes are carried out and the resulting properties are subsequently compared to a conventional tempering process. The results indicate that notch impact energy raises with increasing heating rates to tempering when realizing the same hardness of the samples. The positive effect of high heating rate on toughness is traced back to smaller carbide sizes, as well as smaller carbide spacing and more uniform carbide distribution over the sample.

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Phase evolution and carbon redistribution during continuous tempering of martensite studied with high resolution techniques

Cited by 30 publications

References 37 publications

Comparative Study of the Tempering Behavior of Different Martensitic Steels by Means of In-Situ Diffractometry and Dilatometry

Comparative Study of the Tempering Behavior of Different Martensitic Steels by Means of In-Situ Diffractometry and Dilatometry

Inverse Model for the Control of Induction Heat Treatments

Comparing fast inductive tempering and conventional tempering: Effects on microstructure and mechanical properties

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