高强韧低合金冷作模具钢SDC55的组织和性能

Microstructure and mechanical properties of a low alloy cold-working die steel SDC55

研究了高强韧低合金冷作模具钢的组织和性能。利用JMatpro相图计算辅助进行合金成分设计。运用SEM和TEM等研究了SDC55的微观组织特征和强韧化机制。结果表明,经过淬火回火后,SDC55的组织为回火马氏体基体上均匀分布着弥散细小的碳化物颗粒,残留奥氏体呈薄膜状包裹在马氏体边缘。经930℃淬火180℃两次两小时回火后,SDC55的冲击韧性达到158 J,硬度达到62 HRC。与D2钢比较,硬度基本相当,韧性显著提高。

The microstructure and mechanical properties of a newly developed cold-working die steel SDC55 was investigated.The design of alloy composition was assisted with Jmatpro.The microstructure characterization and toughening mechanism were examined by means of scanning X-ray diffraction（XRD）,electron microscopy（SEM） and transmission electron microscopy（TEM）.The results show that after quenching and tempering,the microstructure of SDC55 steel consists of fine carbides uniformly and dispersively distributed in tempered martensitic matrix,and edges of the tempered martensite are wrapped by thin-film-like retained austenite.After quenching at 930 ℃ and tempering twice at 180 ℃ for two hours each time,the impact toughness and hardness of SDC55 steel are 158 J and 62 HRC,respectively.Comparing with D2 steel,the hardness of SDC55 steel is not changed obviously.However,its impact toughness is improved remarkably.