高氮无镍双相不锈钢等温时效析出行为

Isothermal aging precipitation behavior of high nitrogen nickel-free duplex stainless steel

制备了一种高氮无镍双相不锈钢(Cr19-DSS),利用电子探针(EPMA)和透射电镜(TEM)等研究了其在不同时效条件下的显微组织,分析其时效析出行为。结果表明:Cr19-DSS中的Cr_(2)N析出相易在铁素体/奥氏体界面处形成,并向铁素体内部生长,导致邻近铁素体中Cr元素含量降低。随着Cr_(2)N析出,在铁素体/奥氏体界面处形成了大量贫Cr富Mn的二次奥氏体。随着时效时间延长,析出相数量增多且在铁素体基体内也有少量Cr_(2)N相析出。Cr19-DSS的析出鼻尖温度为750℃,经冷轧变形后,析出鼻尖温度不变,但由于界面共格关系被破坏且晶界增多,导致析出时间大幅度缩短。

A high nitrogen nickel-free duplex stainless steel(Cr19-DSS)was prepared.Microstructure of the Cr19-DSS under different aging conditions was studied by electron probe microanalysis(EPMA)and transmission electron microscopy(TEM),and its aging precipitation behavior was analyzed.The results show that the Cr_(2)N precipitates in the Cr19-DSS are easy to form at the ferrite/austenite interface and grow into the ferrite interior,resulting in the decrease of Cr content in adjacent ferrite.Due to the precipitation of Cr_(2)N,a large number of Cr poor and Mn rich secondary austenite formed at the ferrite/austenite interface.With the increase of aging time,the amount of precipitated phase increases and a small amount of Cr_(2)N phase precipitates in ferrite matrix.The nose tip temperature of the Cr19-DSS is 750℃.After cold rolling deformation,the precipitation nose tip temperature remains unchanged,but the precipitation time is greatly shortened due to the destruction of the interface coherent relationship and the increase of grain boundaries.