Precipitation and hot deformation behavior of austenitic heat-resistant steels: A review

Yinghui Zhou^1,2，Yongchang Liu^1,3，Xiaosheng Zhou¹，Chenxi Liu¹，Jianxin Yu^1,3，Yuan Huang¹，Huijun Li¹，Wenya Li²

1. State Key Lab of Hydraulic Engineering Simulation and Safety, School of Materials Science & Engineering, Tianjin University2. School of Materials Science & Engineering, Northwestern Polytechnical University3. Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration, Shanghai Jiao Tong University

摘 要：The austenitic heat resistant-steels have been considered as important candidate materials for advanced supercritical boilers, nuclear reactors, super heaters and chemical reactors, due to their favorable combination of high strength, corrosion resistance, perfect mechanical properties, workability and low cost.Since the precipitation behavior of the steels during long-term service at elevated temperature would lead to the deterioration of mechanical properties, it is essential to clarify the evolution of secondary phases in the microstructure of the steels. Here, a summary of recent progress in the precipitation behavior and the coarsening mechanism of various precipitates during aging in austenitic steels is made. Various secondary phases are formed under service conditions, like MX carbonitrides, M₂₃C₆ carbides, Z phase, sigma phase and Laves phase. It is found that the coarsening rate of M₂₃C₆ carbides is much higher than that of MX carbonitrides. In order to understand the thermal deformation mechanism, a constitutive equation can be established, and thus obtained processing maps are beneficial to optimizing thermal processing parameters, leading to improved thermal processing properties of steels.

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