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针对20MnCrNi2MoRE低合金耐磨铸钢,采用洛氏硬度计、扫描电镜和透射电镜观察分析其在200~650℃范围内的回火转变过程。结果表明,20MnCrNi2MoRE钢铸态组织为粒状贝氏体,200℃回火时,贝氏体铁素体条首先发生变化,500℃回火时,在贝氏体铁素体条内、晶界及位错处观察到有碳化物析出。300℃回火时观察到(M/A)岛发生分解,650℃回火时(M/A)岛已经完全分解。低于500℃回火时,硬度变化不大,500℃以上回火时,由于位错密度降低和碳化物聚集长大,使硬度显著降低。
For the 20MnCrNi2MoRE low alloy wear-resistant cast steel, the tempering transformation process in 200 ~ 650 ℃ was analyzed by Rockwell hardness tester, scanning electron microscope and transmission electron microscope. The results show that the as-cast microstructure of 20MnCrNi2MoRE steel is granular bainite, and the bainitic ferrite strip first changes when tempered at 200 ℃. When tempered at 500 ℃, Carbide precipitation was observed at the dislocations. At 300 ℃ tempering (M / A) Island was observed decomposition, 650 ℃ tempering (M / A) Island has been completely decomposed. Less than 500 ℃ tempering, the hardness changes little over 500 ℃ tempering, due to the decrease of dislocation density and carbide aggregation growth, the hardness decreased significantly.