Precipitation behavior of second phase in super duplex stainless steel 2507

doi:10.13251/j.issn.0254-6051.2022.05.015

Abstract

Abstract: Second phase precipitation behavior of solid solution treated (1100 ℃×30 min) super duplex stainless steel 2507 hot raled plate after aging at different temperatures (750-1000 ℃) and time (1-240 min) was investigated by using OM, SEM and EBSD. The results show that the microstructure of the tested steel is composed of austenite and ferrite after solution treatment, while after aging at 750-1000 ℃, σ phase and χ phase are detected and identified. When the aging temperature is lower, χ phase precipitates from ferrite phase and exists stably. With aging temperature increasing, the σ phase is formed mainly by the reaction α→σ+γ₂. In addition, with the longer holding time, the metastable χ phase dissolves and promotes σ phase precipitation. Additionally, the aging temperature influences the morphology of the precipitates. At higher aging temperatures (＞950 ℃), the morphology of precipitated phase is mainly sheet σ and γ₂, while at lower aging temperatures, the granular σ phase and χ phase are mainly observed. According to the precipitation behavior and the calculation of TTT diagram of the precipitates, it can be seen that hot rolling deformation shortens the nucleation incubation period of the second phases in the SDSS 2507, increases the precipitation rate, and the precipitation sensitive temperature is about 950 ℃.

Key words: super duplex stainless steel 2507, σ phase, aging treatment, precipitation behavior

CLC Number:

TG142.1

Gu Guochao, Li Ruifen, Xin Zhenmin, Yuan Zhaofu, Cui Shugang, Xu Wenhua, Lü Yupeng. Precipitation behavior of second phase in super duplex stainless steel 2507[J]. Heat Treatment of Metals, 2022, 47(5): 92-97.

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