2205双相不锈钢高温下σ相析出的原位观察

IN SITU OBSERVATIONS OFσPHASE PRECIPITATION AT HIGH TEMPERATURE IN 2205 DUPLEX STAINLESS STEEL

利用共焦激光扫描显微镜(CSLM)原位观察了2205双相不锈钢850、900、950℃保温1 h时效处理过程中σ相的析出行为。结合扫描电镜(SEM)、能谱分析(EDS)和透射电镜(TEM)的分析结果可以认为,经过时效处理后,2205双相不锈钢中主要析出相类型为σ相,通常在铁素体晶内与晶界析出。实验结果还显示,由于α/γ晶界位置的减少以及Cr、Mo等合金元素的匮乏,致使2205双相不锈钢中σ相的析出时间随着时效温度的增加而延长,其析出量则呈现出减小的趋势;但在相同时效温度条件下,σ相析出量随时效时间的延长而增多。

The precipitation behavior of σ phase in a 2205 duplex stainless steel aged at tem- peratures of 850 ℃, 900℃ and 950 ℃ each for 1 h were observed in situ by using a confocal laser scanning microscope （CSLM）. Combined with the analyzing results of SEM, EDS and TEM, it was shown that the main precipitate phase in 2205 duplex stainless steel was σ phase, which existed in ferritic grains and grain boundaries. In addition, with the increasing of aging temperature, the precip- itation time of σ phase in testing steel was prolonged and the precipitation content was reduced be- cause of the decreased nucleation sites of σ phase in σ/γ grain boundary and the weakened effect of Cr, Mo alloy element, the precipitation amounts of σ phase were increased with the prolonged holding time.