材料科学
微观结构
冶金
铁氧体(磁铁)
粒度
碳化物
成形性
晶粒生长
复合材料
作者
Liu Jing,Luo Xin-Hong,HU Xiao-Jiang,Shi Liu
出处
期刊:Acta Metallurgica Sinica
日期:2011-06-11
卷期号:47 (6): 688-696
标识
DOI:10.3724/sp.j.1037.2011.00059
摘要
Ultra-purified ferrite stainless steels (UP-FSS) are widely used in the fields of auto- mobile, household appliances etc. Much better performance than conventional ferrite stainless steels is obtained by minimizing the interstitial elements level in UP-FSS. However, some negative effects, such as degradation of the formability and ridging-resistance, are also brought by purifying the steels, which lead to abnormally growth of the columnar grains. Moreover, the grains in heat affected zone (HAZ) are apt to coarsen during welding process. One of the effective ways to resolve such problems is to increase the equiaxial grain ratio in as-cast microstructure and refine the grain size. Micro-alloying of steels with strong carbide and nitride former, such as Ti and Nb, is a way to do that. In this work, the effects of Ti and Nb micro-alloying on the as-cast, as-rolled, and HAZ microstructures of the ultra- purified 11%Cr ferrite stainless steels with different interstitial element levels were investigated by both experimental research and thermodynamic calculation. The results indicated that the effect of Ti and Nb micro-alloying was better when the content of C and N in the steel was 0.0163%, which showed the minimum grain size in as-cast, as-rolled, and HAZ microstructures, and the equiaxial grain ratio in as-cast microstructure was evidently improved as well. It was found by calculation that, with increas- ing of C and N content and addition of Ti and Nb to the steels, the solid-liquid two-phase region was broadened. This was beneficial to increase the undercooling in front of the liquid-solid interface and the probability of heterogeneous nucleation, and consequently, increase the equiaxial grain ratio and
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