It is of great theoretical significance to study the solidification kinetics of metal materials for improving the microstructure and properties. In this paper, the Differential Scanning Calorimetry (DSC) was used to measure the enthalpy change of solidification process of 1035 steel at different cooling rates. The activation energy of the solidification process was determined by the equal conversion method based on the data of enthalpy. The mechanism function of the solidification process was also determined. It is shown that the value of the activation energy of solidification process varied with the solidification fraction, and the mechanism functions of solidification process are different in different temperature ranges, which are –ln(1– α) for 1 504-1 502 °C –ln(1–α)1/2 for 1 500-1 942 °C and –ln(1– α)2/5 for_1 490 °C respectively

Guo, L. L.

Tan, G. L.

Tang, D.

Wang, F. D.

Zhang, Q. Q.

English

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343METALURGIJA 62 (2023) 3-4, 343-345G. L. TAN, D. TANG, L. L. GUO, Q. Q. ZHANG, F. D. WANGKINETICS ANALYSIS OF SOLIDIFICATION PROCESS  OF 1035 STEEL AT DIFFERENT COOLING RATESReceived – Primljeno: 2023-03-04Accepted – Prihvaćeno: 2023-04-20Original Scientific Paper – Izvorni znanstveni radIt is of great theoretical significance to study the solidification kinetics of metal materials for improving the micro-structure and properties. In this paper, the Differential Scanning Calorimetry (DSC) was used to measure the en-thalpy change of solidification process of 1035 steel at different cooling rates. The activation energy of the solidifica-tion process was determined by the equal conversion method based on the data of enthalpy. The mechanism func-tion of the solidification process was also determined. It is shown that the value of the activation energy of solidifica-tion process varied with the solidification fraction, and the mechanism functions of solidification process are differ-ent in different temperature ranges, which are –ln(1–α) for 1 504-1 502 °C –ln(1–α)1/2 for 1 500-1 942 °C and –ln(1–α)2/5 for≤1 490 °C respectively.Keywords: 1035 steel, solidification kinetics, enthalpy, the activation energy, mechanismISSN 0543-5846METABK 62(3-4) 343-345 (2023)UDC – UDK 669.15: 66. 065:536. 722: 536. 777:539. 26 = 111INTRODUCTIONThe solidification process is usually process for the most metal materials in the during preparation. The melt flow, solute and phase distribution, morphology evolution of solid/liquid interface and crystal orienta-tion for the solidification process, which is significantly affect the microstructure of materials. As well, the per-formance of metal materials ultimately depends on its microstructure, which directly depends on the distribu-tion of microstructure and composition.[1] The solidifi-cation process for the metal materials can greatly deter-mine the distribution of microstructure and composi-tion. Therefore, solidification process has a significant impact on the performance of metal materials. The so-lidification process not only determines the final perfor-mance of the product directly, but also indirectly[2]. In recent decades, researchers have been trying to control the solidification process by various means to develop solidification. Such as directional solidification [3], rapid solidification [4-5], centrifugal casting [6-7], deep supercooling [8] and external physical field control [9]. Which not only meet the needs of scientific and techno-logical development and industrial production, but also enriched the theory of metal solidification. As a result, it is of great significance to study the solidification ki-netics of metal.G. L. Tan. L. L. Guo. Q. Q. Zhang. F. D. Wang. School of Materials Science and Engineering, Yingkou Institute of Technology, Liaoning, China, (corresponding author E-mail: zqq@yku.edu.cn, guolili@yku.edu.cn, wfd@yku.edu.cn)D. Tang. School of Mechanical and Power Engineering, Yingkou In-stitute of Technology Liaoning, China. (corresponding author E-mail: tangdan@yku.edu.cn)In this paper, thermal analysis technology is used to obtain the enthalpy of the solidification process of 1035 steel. The activation energy and mechanism of the so-lidification process of 1035 steel were determined by the equal conversion fraction method based on the data of enthalpy.EXPERIMENT AND RESULTThe sample size: thickness of about 2 mm and width of about 2,5 mm. The experiment were carried out by the Labsys synchronous DSC. The heating temperature is from 30 °C to 1 550 °C at a heating rate of 10 °C/min, and then drops to room temperature at a cooling rate of 5 °C/min, 10 °C/min, 15 °C/min, 20 °C/min. The blank without sample experiment was carried out at different temperature program in order to reduce the experimen-tal error. According to the literature[10], we can con-Figure 1  Relationship between heat flow and temperature at different cooling rates344  METALURGIJA 62 (2023) 3-4, 343-345G. L. TAN et al.: KINETICS ANALYSIS OF SOLIDIFICATION PROCESS OF 1035 STEEL…cluded the relationship between the solidification frac-tion and temperature in the solidification process at dif-ferent cooling rates are shown in Figure 1.KINETICS ANALYSISThe activation energy of solidification can be ob-tained by the Flynn-Wall-Ozawa method. The formula is shown in the following[10].  (1)Where, A is the pre-exponential factors , T is tem-perature, g(α) is the kinetics mechanism function of  solidification process, αDSC is solidification fraction, E is activation energy, R is gas constant, and β is cooling rate.According to Eq.(1), when α is a constant value, g(α) is also a constant value. Therefore, by making lg β – 1/T curve, E under different conversion ratio could be calculated through the curve’s slope. The relationship the E calculated by the Eq.(1) with the solidification fraction is shown in Figure 2.As seen from the Figure 2, the solidification activa-tion energy of 1035 steel is increases with the solidifica-tion fraction. The value of solidification activation en-ergy increased from 595 kJ/mol to 675 kJ/mol at the range 0-0.4. The activation energy value is increased about 13.4%. Subsequently, the solidification activation energy decreases with the solidification activation. At the end of the solidification process, the value of the activation energy is about 615 kJ/mol. The possible rea-son is that nucleation is difficult in the initial solidifica-tion. The energy during its growth is small when the new phase nucleus reaches a certain size. Therefore, the activation energy of solidification process is increase with the solidification fraction at the begging solidifica-tion process , and then decreases with the solidification fraction.The kinetic mechanism function of the solidification process can be obtained from the Eq.(2)  (2)In the Eq.(3), at the same temperature T, the last three terms on the right side of Eq. 2 were constant val-ues. Therefore, by making ln[–ln(1–α)]–lnβ curve, the n value could be calculated through the slope, and the ki-netic mechanism function could be obtained. The re-sults are shown in the Table 1.Figure 2  Relationship between activation energy  and solidification fractionTable 1 The mechanism function calculated from Eq.(2)T/ °C R n g(αDSC)1 504 0,964 -1,0 –ln(1–α)1 502 0,901 -1,0 –ln(1–α)1 500 0,991 -2,0 –ln(1–α)1/21 498 0,929 -2,0 –ln(1–α)1/21 496 0.971 -2,0 –ln(1–α)1/21 494 0.985 -2,0 –ln(1–α)1/21 492 0.910 -2,0 –ln(1–α)1/21 490 0,953 -2,5 –ln(1–α)2/5As seen from the Table 1, The values of n are varied with the temperatures. We can con clued that kinetic mechanism function are different with the temperature. Therefor, the solidification process of 1035 steel is a multi-step complex reaction. According to the tempe-rature range, the solidification process of 1035 steel can be divided into three stages. Based on the kinetic mechanism functions commonly used in solid-state re-action[10], the kinetic mechanism functions of the above three stages are respectively –ln(1–α), –ln(1–α)1/2, –ln(1–α)2/5. It concluded that the solidification process of 1035 steel conforms to an accommodated nuclei  production and nuclei growth model according to the kinetic mechanism function.CONCLUSIONThe activation energy of solidification process of 1035 steel is varied with the solidification fraction at different cooling rates. The kinetics mechanism func-tions is different with the temperature range. We can concluded that the solidification process of 1035 steel is not a simple one-step reaction.The kinetics mechanism functions for the solidification process of 1035 steel  obtained by Criado-Ortega method are –ln(1–α), –ln(1–α)1/2, –ln(1–α)2/5 respectively. The solidification process of 1035 steel conforms to an accommodated nuclei production and nuclei growth model.AcknowledgementsWe gratefully acknowledge the Liaoning Province Regional Joint Fund Project (2021-YKLH-02); the Li-aoning Province Regional Joint Fund Project (2022-345G. L. TAN et al.: KINETICS ANALYSIS OF SOLIDIFICATION PROCESS OF 1035 STEEL…METALURGIJA 62 (2023) 3-4, 343-345YKLH-15) and the Liaoning Province Natural Science Foundation of china(20180550632); General project of Liaoning Provincial Department of Education (LJKZ1198); Excellent Talents of Science and Technol-ogy in Yingkou Institute of Technology (RC201903).REFERENCE[1] I S Jung , H S Jang , M H Oh , et al. Microstructure control of TiAl alloys containing β stabilizers by directional solidification[J], Materials Science and Engineering: A, 329-331( 2002), 13-18.[2] D R Johnson, H Inui , M Yamguchi. Directional solidifica-tion and microstructural control of the TiAlTi3Al lamellar microstructure in TiAl-Si alloys [J], Acta Materialia, 44 (1996), 2523-2535.[3] X F Ding , J P Lin , L Q Zhang, et al. Lamellar orientation con-trot in a Ti-46Al-5Nb alloy by directional solidifica-tion [J], Scripta Materialia, 65(2011), 61-64.[4] Y J Liang , X Cheng , H M Wang . A new microsegregation model for rapid solidification multicomponent alloys and its application to single-crystal nickel-base superalloys of laser rapid directional solidification[J], Acta Materialia, 118(2016), 17-27.[5] J D Roehlevg , D R Coughlin , J W Gibbs , et al. Rapid solid-ification growth mode transitions in Al-Si alloys by dynamic trans-mission electron microscopy[J], Acta Mate-rialia, 131 (2017), 22-30.[6] A L Ramirez-Ledesma, E Lopez-molina , H F Lopez, etal. Athermal ε-martensite transformation in a Co-20Cr alloy: Effect of rapid solidification on plate nucleation[J], Acta Materialia, 111 (2016), 138-147.[7] Y Watanabe, H Eryu, K Matsuura. Evaluation of three-di-mensional orientation of Al3Ti platelet in Al-based functio-nally graded materials fabricated by a centrifugal casting technique[J], Acta Materialia, 49(2001), 775-783.[8] Y F Mo, Z A Tian, R S Liu, et al. Molecular dynamics study on microstructural evolution during crystallization of rapidly super-cooled zirconium melts [J], Journal of Al-loys and Compounds, 688 ( 2016), 654-665.[9] T Konishi, H Nagai, Y Nakata, et al. Microstructure and magnetic properties of Sm2Fe17 alloy prepared by unidirec-tional solidification in microgravity [J]. Journal of Magne-tism and Magnetic Materials, 269 (2004), 48-53.[10] D. Tang, Q. Q. Zhang, F. D. Wang, et al.Analysis of tran-sformation kinetics of 1035 steel at different cooling rates. Metalurgija, 62 (2023) 2,204-206.Note:  The responsible translator for language English is associate  professor W. H. Ma - Yingkou Institute of Technology,  Liaoning, China. The translator has translated the manuscript (Kinetics analysis of solidification process of 1035 steel  at different cooling rates).

Kinetics analysis of solidification process of 1035 steel at different cooling rates

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