冷变形和固溶温度对HR3C钢中σ相析出行为的影响

Effect of Cold Deformation and Solid Solution Temperature onσ-phase Precipitation Behavior in HR3C Heat Resistant Steel

结合HR3C钢制备工艺,综合研究冷变形和固溶处理工艺对其在时效过程中σ相的析出动力学和相关力学性能的影响。结果表明:冷变形和固溶温度均对该钢中σ相的析出有着较大的影响,变形量的增加会促进σ相的时效析出,升高固溶处理温度有助于抑制HR3C钢中σ相的析出行为,但却在一定程度上增大晶粒尺寸。σ相析出量随时间延长先缓慢增加,后快速析出,最后达到稳态值约5.7%(体积分数)。变形量的增加使HR3C钢时效过程中冲击韧性显著降低,而固溶温度的升高虽然增加了固溶态试样的冲击韧性但降低了时效过程中的冲击韧性。

HR3C steel,widely applied in ultra-supercritical power plant,suffers an intergranular embrittlement problem during long-term high-temperature ageing or service,which will be enhanced by the precipitation ofσphase.Research has showed that the precipitation behaviors ofσphase are different significantly as the difference of manufacturers,which relates to the preparation process of colddeformation&solid-solution treatment.In this work,the effects of cold deformation and solution treatment on the precipitation kinetics ofσphase and related mechanical properties for HR3C steel during the ageing process were studied.The results show that cold-deformation and solid solution temperature both have a significant influence on the precipitation ofσphase in the steel.The increase of cold-deformation will promote the precipitation ofσphase,and rising solution temperature helps to inhibit the growth ofσphase but increase the grain size.The precipitation kinetics study ofσphase in HR3C steel with different pre-treatment shows thatσphase growths slowly at first,and then gets into a rapid precipitation period,and finally reaches a steady-state with a value of about 5.7%(volume fraction).The impact toughness analysis shows that the increase of cold-deformation would lower down the impact toughness of HR3C steel during the ageing procedure,while the rise of the solid-solution temperature increases the impact toughness before ageing and reduces it during ageing.