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采用高温XRD技术研究了超级双相不锈钢00Cr25Ni7Mo3.5N表面原位氧化行为。对该钢种在空气条件下进行连续加热,选取一些温度点进行测试,研究了其表面氧化物的生长规律,并分析了第二相的析出行为。结果表明,600℃以下表面组织均为α、γ两相结构。800℃时α相开始被氧化成-αFe2O3,900℃时α相被氧化成-αFe2O3和Fe3O4,继续加热至1 000℃时α相全部氧化消失。即使温度升高到1 100℃,γ相也没有被氧化。而在空气条件下,不同温度水淬样品内部的室温组织始终保持α、γ两相结构,并且随温度增加,α相比例逐渐增加。此外,加热过程中还发现表面与内部的σ相几乎同步产生和消失。
The in-situ oxidation behavior of 00Cr25Ni7Mo3.5N super duplex stainless steel was investigated by high temperature XRD. The steel was continuously heated under air, some temperature points were selected for testing, the growth of the surface oxide was studied, and the precipitation behavior of the second phase was analyzed. The results show that the surface microstructure below 600 ℃ are α, γ two-phase structure. The α phase begins to be oxidized to -αFe2O3 at 800 ℃, the α phase is oxidized to -αFe2O3 and Fe3O4 at 900 ℃, and all the α phase disappears when heated to 1000 ℃. The γ phase is not oxidized even when the temperature is increased to 1,100 ° C. Under air condition, the room-temperature microstructure of water quenched samples kept the α, γ phase structure at all temperatures, and the proportion of α phase increased with the increase of temperature. In addition, the heating process also found that the surface and the internal sigma phase almost simultaneously produce and disappear.