Determination and analysis of CCT curve of LC3 cryogenic cast steel

doi:10.13251/j.issn.0254-6051.2024.12.023

Abstract

Abstract: DIL 805A type fully automatic phase transformer was used to determine the expansion curve of LC3 cryogenic cast steel under different cooling rates between 0.05-150 ℃/s, and the tangent method was used to determine the phase transformation point Ac₁ of 700 ℃ and Ac₃ of 849 ℃. Combined with microstructure analysis and microhardness to determine the actual transformation products, and the CCT curve was plotted using Origin software. The results show that the microstructure is ferrite + pearlite when the cooling rate is 0.05-2 ℃/s, ferrite + pearlite +bainite when it is 5-20 ℃/s, bainite + martensite when it is 30-50 ℃/s, martensite + retained austenite when it is 80 ℃/s, and martensite when it is 100-150 ℃/s. Hardness of the LC3 cryogenic cast steel gradually increases from 168 HV10 to 453 HV10 with the increasing of cooling rate. Martensite critical cooling rate is about 80 ℃/s.

Key words: LC3 cryogenic cast steel, CCT curve, tangential method, critical cooling rate

CLC Number:

TG141

Chen Kun, Gong Wenguo, Chang Xueting, Yin Yansheng. Determination and analysis of CCT curve of LC3 cryogenic cast steel[J]. Heat Treatment of Metals, 2024, 49(12): 137-141.

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