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采用扫描电镜、透射电镜和洛氏硬度计研究了20MnCrNi2Mo钢贝氏体的回火转变过程。结果表明,20MnCrNi2Mo钢粒状贝氏体在200℃回火时,M/A岛基本没有发生分解;随回火温度的升高,M/A岛逐渐发生分解,在500℃回火时M/A岛大量分解,位错密度降低,且有碳化物析出。200~500℃回火时硬度变化不大,当回火温度高于500℃时,M/A岛完全分解,析出碳化物聚集长大,硬度值急剧降低。
The tempering transformation of 20MnCrNi2Mo steel bainite was investigated by scanning electron microscopy, transmission electron microscopy and Rockwell hardness tester. The results show that the M / A island basically does not decompose when the granular bainite of 20MnCrNi2Mo steel is tempered at 200 ℃. The M / A island gradually decomposes with the increase of tempering temperature. When the tempering at 500 ℃, the M / A A large number of island decomposition, dislocation density decreased, and carbide precipitation. When the tempering temperature is higher than 500 ℃, the M / A island is completely decomposed and the precipitated carbide grows up and the hardness decreases sharply.