北京科技大学学报
北京科技大學學報
북경과기대학학보
JOURNAL OF UNIVERSITY OF SCIENCE AND TECHNOLOGY BEIJING
2014年
8期
1025-1031
,共7页
王金永%刘建华%刘建飞%冯美兰%周明伟%廖志%贾友生
王金永%劉建華%劉建飛%馮美蘭%週明偉%廖誌%賈友生
왕금영%류건화%류건비%풍미란%주명위%료지%가우생
IF钢%氮化钛%凝固%偏析%析出
IF鋼%氮化鈦%凝固%偏析%析齣
IF강%담화태%응고%편석%석출
IF steel%titanium nitride%solidification%segregation%precipitation
结合冶金热力学和凝固偏析模型分析了Ti-IF钢凝固过程中TiN的析出特点. Ti-IF钢凝固前期钢液中TiN夹杂无法生成,固相中TiN源自低温固相析出；凝固固相分数达到0.64时,Ti、N组元在凝固前沿富集程度增加,凝固前沿固相中开始有TiN析出；凝固末期,Ti和N的富集程度进一步增大,固液相中均能有TiN析出.采用扫描电镜分析了TiN在铸坯中的分布,从铸坯表层到中心TiN数量和尺寸存在显著变化：从铸坯表层向中心方向TiN尺寸不断增大,平均尺寸从1~2μm增大到5μm,在距离表层70~80 mm处尺寸达到最大；在铸坯厚度中间位置,TiN尺寸较大,平均尺寸为5μm左右；在铸坯中心TiN尺寸又有所变小,平均尺寸为3μm左右；在铸坯表层TiN密集程度较高,在铸坯中间和中心TiN数量密集程度显著降低. IF钢铸坯中TiN析出时机及其尺寸和数量与Ti、N组元偏析和凝固冷却速度关系密切.
結閤冶金熱力學和凝固偏析模型分析瞭Ti-IF鋼凝固過程中TiN的析齣特點. Ti-IF鋼凝固前期鋼液中TiN夾雜無法生成,固相中TiN源自低溫固相析齣；凝固固相分數達到0.64時,Ti、N組元在凝固前沿富集程度增加,凝固前沿固相中開始有TiN析齣；凝固末期,Ti和N的富集程度進一步增大,固液相中均能有TiN析齣.採用掃描電鏡分析瞭TiN在鑄坯中的分佈,從鑄坯錶層到中心TiN數量和呎吋存在顯著變化：從鑄坯錶層嚮中心方嚮TiN呎吋不斷增大,平均呎吋從1~2μm增大到5μm,在距離錶層70~80 mm處呎吋達到最大；在鑄坯厚度中間位置,TiN呎吋較大,平均呎吋為5μm左右；在鑄坯中心TiN呎吋又有所變小,平均呎吋為3μm左右；在鑄坯錶層TiN密集程度較高,在鑄坯中間和中心TiN數量密集程度顯著降低. IF鋼鑄坯中TiN析齣時機及其呎吋和數量與Ti、N組元偏析和凝固冷卻速度關繫密切.
결합야금열역학화응고편석모형분석료Ti-IF강응고과정중TiN적석출특점. Ti-IF강응고전기강액중TiN협잡무법생성,고상중TiN원자저온고상석출；응고고상분수체도0.64시,Ti、N조원재응고전연부집정도증가,응고전연고상중개시유TiN석출；응고말기,Ti화N적부집정도진일보증대,고액상중균능유TiN석출.채용소묘전경분석료TiN재주배중적분포,종주배표층도중심TiN수량화척촌존재현저변화：종주배표층향중심방향TiN척촌불단증대,평균척촌종1~2μm증대도5μm,재거리표층70~80 mm처척촌체도최대；재주배후도중간위치,TiN척촌교대,평균척촌위5μm좌우；재주배중심TiN척촌우유소변소,평균척촌위3μm좌우；재주배표층TiN밀집정도교고,재주배중간화중심TiN수량밀집정도현저강저. IF강주배중TiN석출시궤급기척촌화수량여Ti、N조원편석화응고냉각속도관계밀절.
Characterization of TiN precipitation during Ti-IF steel solidification was analyzed by thermodynamics and the solidifica-tion segregation model. It is found that TiN inclusions cannot precipitate in liquid steel before solidification. In the earlier stage of so-lidification, TiN precipitates at low temperature in solidified steel. When the solid fraction reaches to 0.64, TiN can precipitate in solid steel around the solidification front at higher temperatures, due to the increased enrichment of Ti and N. However, at the end stage of solidification, TiN can not only precipitate in solidified steel, but also in molten steel, for the segregation of Ti and N is getting seri-ous. TiN distribution in the Ti-IF slab was observed by scanning electron microscopy ( SEM) . The results show that the number and size of TiN precipitates vary a lot from the slab surface to the center. The TiN size is increasing from the slab surface to the center, from 1-2μm to 5μm, and it is maximum in the area of 70 to 80 mm from the slab surface. In the middle of the slab in thickness, the TiN size is large, with an average size of 5μm;while in the center of the slab, the TiN size is getting smaller again, with an average size of 3μm. The TiN denseness is high in the surface layer of the slab, but decreases significantly in the center and middle. The pre-cipitation moment, the size and number of TiN precipitates are closely related with the segregation of Ti and N and the solidification rate.
