【摘要】：為了研究鋼錠點(diǎn)狀偏析區(qū)微觀組織特點(diǎn),對(duì)CrMo鋼鍛坯中的斑點(diǎn)偏析區(qū)域進(jìn)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(gè)維度方向尺寸相近的點(diǎn)狀偏析。偏析區(qū)中鉻、鉬元素質(zhì)量分?jǐn)?shù)相對(duì)較高,在冷卻后點(diǎn)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(cuò)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(diǎn)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(diǎn)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(shí)受枝晶表面的物理吸附作用聚集,同時(shí)增加了枝晶區(qū)域液相的黏度,導(dǎo)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(shí)間,將有效緩解鋼錠中斑點(diǎn)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(xué)材料與冶金學(xué)院;貴州省材料結(jié)構(gòu)與強(qiáng)度重點(diǎn)實(shí)驗(yàn)室;首鋼貴陽特殊鋼有限責(zé)任公司;
【基金】：國家自然科學(xué)基金資助項(xiàng)目(51461007) 貴州省重大應(yīng)用基礎(chǔ)研究資助項(xiàng)目(黔科合JZ字[2014]2003)
【分類號(hào)】：TG142.1

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