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以12Cr铁素体钢为研究对象,通过高频感应炉熔炼获得3种冷却速率(5、0.5和0.05℃/s)铁素体钢的铸态试样,研究了冷却速率对该材料相组成和显微组织的影响。结果表明:冷却速率在0.5～5℃/s,12Cr铁素体钢基体组织为铁素体。随着冷却速率的减小,晶粒尺寸逐渐增大,晶界析出碳化物逐渐粗大,晶内析出的针状碳化物趋于细小弥散。在冷却速率为5℃/s时,晶界碳化物呈树枝状,宽度约为1μm;冷却速率低于0.5℃/s时,晶界碳化物呈网状,宽度大于4μm;冷却速率减小到0.05℃/s时,晶粒内出现近球形碳化物。
Taking 12Cr ferritic steel as the research object, three kinds of as-cast samples of ferritic steel with cooling rate (5, 0.5 and 0.05 ℃ / s) were obtained by high frequency induction furnace smelting. The effects of cooling rate on the phase composition And the effects of microstructure. The results show that the cooling rate is 0.5 ~ 5 ℃ / s and the microstructure of 12Cr ferritic steel is ferrite. With the decrease of the cooling rate, the grain size gradually increases, and the precipitated carbides in the grain boundaries gradually become coarse and the precipitated acicular carbides in the crystal tend to be finely dispersed. When the cooling rate is 5 ℃ / s, the grain boundary carbides are dendritic with a width of about 1μm. When the cooling rate is lower than 0.5 ℃ / s, the grain boundary carbides are reticular with a width of more than 4μm. The cooling rate decreases to At 0.05 ℃ / s, near-spherical carbides appear in the grains.