针对核电海水循环泵叶轮用双相不锈钢材料, 研究了不同时效温度、时间及固溶后不同冷却速率对双相不锈钢组织和力学性能的影响,结果表明, 在800-850 ℃保温5 min或冷却速率低于7.5 ℃/min时, 材料的冲击韧性和延伸率急剧下降. OM, SEM和冲击断口观察及XRD分析证实, σ相的析出对力学性能有破坏性影响, 且随着时效时间的延长, σ相变得粗大, 析出位置从 γ/δ相界扩展到整个δ相.
Effects of heat treatment on microstructure and mechanical property of a cast duplex stainless steel used as making impeller of seawater circular pump in nuclear power plant were investigated. The results demonstrate that the impact energy and elongation
decrease sharply when heat-treated time was longer than 5 min at 800-850 ℃ or when the cooling rate was less than 7.5 ℃/min. The σ phases have been identified through SEM and XRD. The weakness of the mechanical properties is attributed to the precipitation of σ phase. With increasing aging time, the σ phase coarsened and the nucleation position moved from the γ/δ interfaces into the whole ferrite phase.
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