Effect of solid solution treatment on microstructure and carbides of 53Cr21Mn9Ni4N heat-resistant steel

doi:10.13251/j.issn.0254-6051.2022.04.006

Abstract

Abstract: Phase diagrams of 53Cr21Mn9Ni4N heat-resistant steel were calculated by using the FSstel database of FactSage software, the influence of nitrogen on phase transformation and precipitation during solidification and cooling was analyzed, and the equilibrium solidification and cooling phase transformation path diagram of the 53Cr21Mn9Ni4N heat-resistant steel was obtained. The microstructure and carbide evolution of the 53Cr21Mn9Ni4N heat-resistant steel were studied after solution treatment at 1200 ℃ respectively for 3 min, 10 min, 20 min, 40 min and 60 min by OM, SEM, XRD and EDS. The results indicate that the full-phase transformation path of 53Cr21Mn9Ni4N heat-resistant steel during the cooling process from 1600 ℃ to 300 ℃ is as follows: Liquid+Gas → Liquid → Liquid+δ-Ferrite → Liquid+δ-Ferrite+γ-Austenite → Liquid+γ-Austenite → γ-Austenite → γ-Austenite+M₂₃C₆→ γ-Austenite+M₂(C,N)+M₂₃C₆→ γ-Austenite+M₂(C,N)+M₂₃C₆+α-Ferrite → γ-Austenite+M₂(C,N)+M₂₃C₆+α-Ferrite+σ. The precipitation temperature of M₂₃C₆ decreases with the increase of nitrogen content, the precipitation temperature of M₂(C,N) increases with the increase of nitrogen content, and the precipitation of M₂₃C₆ is inhibited by the precipitation of M₂(C,N). The as-cast microstructure of the 53Cr21Mn9Ni4N heat-resistant steel is very uneven, the austenite grows in the form of dendrites and a large number of lamellar carbides precipitate between the dendrites. With the increase of solution treatment time, the lamellar carbides distributed between the dendrites gradually become massive and rod-shaped, the quantity of carbides gradually decreases, and the thick dendrites gradually become finer. The microstructure and carbides of the 53Cr21Mn9Ni4N heat-resistant steel after solution treatment at 1200 ℃ are all obviously improved.

Key words: 53Cr21Mn9Ni4N heat-resistant steel, solution treatment, carbide, solidification mode, phase diagram calculation

CLC Number:

TG142.1

Wang Yinghu, Zheng Huaibei, Liu Tingyao, Song Lingxi, Bai Qingqing. Effect of solid solution treatment on microstructure and carbides of 53Cr21Mn9Ni4N heat-resistant steel[J]. Heat Treatment of Metals, 2022, 47(4): 39-45.

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