【摘要】：為了研究鋼錠點狀偏析區(qū)微觀組織特點,對CrMo鋼鍛坯中的斑點偏析區(qū)域進行了分析研究。研究表明,鋼坯中的元素偏析區(qū)沿鍛造方向拉伸且尺寸較小,可判斷原鑄錠中的偏析為3個維度方向尺寸相近的點狀偏析。偏析區(qū)中鉻、鉬元素質(zhì)量分數(shù)相對較高,在冷卻后點狀偏聚區(qū)形成貝氏體組織,與基體的鐵素體、珠光體組織呈交錯分布的特征,且夾雜物在偏析區(qū)富集比較明顯,局部偏析區(qū)還存在氣孔。鋼中的點狀偏析的出現(xiàn)主要原因是鋼液凝固前沿過冷度降低,在成分過冷條件下,高熔點鉻、鉬組元在枝晶表面局部富集,隨溫度的下降,鋼液中Mn S夾雜物同時受枝晶表面的物理吸附作用聚集,同時增加了枝晶區(qū)域液相的黏度,導致氣體溢出困難,在凝固后局部形成氣孔。通過提高鋼液凝固速度,降低鋼液在固液兩相區(qū)的停留時間,將有效緩解鋼錠中斑點偏析的形成。
[Abstract]:In order to study the microstructure of spot segregation zone of ingot, the spot segregation region in CrMo steel forging billet was analyzed and studied. The results show that the element segregation zone in the billet is stretched along the forging direction and the size is small, so it can be judged that the segregation in the original ingot is a point segregation with similar dimensions in three dimensions. The mass fraction of chromium and Mo in the segregation region is relatively high. The bainitic structure is formed in the punctate segregation zone after cooling, which is crisscrossed with the Ferrite and pearlite structure of the matrix, and the inclusions are enriched obviously in the segregation zone, and there are still pores in the local segregation zone. The main reason for the occurrence of point segregation in steel is the decrease of undercooling at the solidification front of molten steel. under the condition of composition undercooling, the high melting point chromium and Mo components are locally enriched on the dendritic surface. With the decrease of temperature, the Mn S inclusions in molten steel are aggregated by the physical adsorption of dendritic surface at the same time, the viscosity of liquid phase in dendritic region is increased, which leads to the difficulty of gas overflow and the local formation of pores after solidification. By increasing the solidification rate of molten steel and reducing the residence time of molten steel in the solid-liquid two-phase region, the formation of spot segregation in ingots will be effectively alleviated.
【作者單位】： 貴州大學材料與冶金學院;貴州省材料結(jié)構(gòu)與強度重點實驗室;首鋼貴陽特殊鋼有限責任公司;
【基金】：國家自然科學基金資助項目(51461007) 貴州省重大應(yīng)用基礎(chǔ)研究資助項目(黔科合JZ字[2014]2003)
【分類號】：TG142.1

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