摘要
通过电子背散射衍射(EBSD)、透射电子显微镜(TEM)及其能谱(EDS)分析和力学性能测试,系统对比Cu、Ni及Cu/Ni复合添加中锰钢在500℃时效后的显微组织演变与屈服强度变化,并深入揭示其析出强化机理。结果表明:含Cu钢、含Ni钢和含Cu/Ni钢经500℃时效处理因析出强化使屈服强度分别增加了125、540 MPa和575 MPa左右,含Ni和含Cu/Ni钢的析出强化显著高于含Cu钢,主要是因为前两者中析出的纳米颗粒数量远大于Cu钢。虽然加入Cu可促进NiAl相析出,使得Cu/Ni钢中的Cu-NiAl复合析出相尺寸和数量均大于Ni钢中的单一NiAl相,但Cu-NiAl复合析出相析出强化效果并没有显著高于单一NiAl相。这是因为后者单一析出的尺寸小于临界尺寸,通过位错剪切机制实现强化,而前者复合析出相尺寸超过临界尺寸,从而通过位错绕过机制强化,导致析出强化效果减弱,因此Cu/Ni钢的时效析出强化效果并未高于Ni钢。
The microstructural evolution and yield strength changes of medium-Mn steels with Cu,Ni,and Cu/Ni composite additions after aging at 500℃are systematically compared using electron backscatter diffraction(EBSD),transmission electron microscopy(TEM)with energy-dispersive spectroscopy(EDS),and mechanical property tests.The precipitation strengthening mechanism is further revealed.The results show that aging at 500℃increases the yield strength by approximately 125,540 MPa,and 575 MPa for the Cu,Ni,and Cu/Ni alloyed steels,respectively,due to precipitation strengthening.The strengthening effect in the Ni and Cu/Ni alloyed steels is much greater than that in the Cu alloyed one,mainly because the number of precipitated nanoparticles in the former two steels is much greater than that in the Cu alloyed steel.Although Cu addition promotes the precipitation of NiAl phases,leading to larger size and higher number of Cu-NiAl composite precipitates in the Cu/Ni alloyed steel compared with the single NiAl precipitates in the Ni alloyed steel,the precipitation strengthening effect of the Cu-NiAl composite precipitates is not significantly higher than that of the single NiAl precipitates.This is because the latter,with its single precipitate sizes below the critical size,strengthen through the dislocation shearing mechanism,whereas the former,with its composite precipitates exceeding the critical size,strengthen via the dislocation Orowan mechanism,resulting in weakened precipitation strengthening.Consequently,the aging precipitation strengthening effect of Cu/Ni steel is not higher than that of the Ni steel.
作者
赖伟强
丁方林
胡斌
罗海文
LAI Weiqiang;DING Fanglin;HU Bin;LUO Haiwen(School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China)
出处
《材料工程》
北大核心
2026年第2期268-276,共9页
Journal of Materials Engineering
基金
国家自然科学基金项目(52233018,51831002)。
关键词
中锰钢
时效
析出相
复合析出
剪切机制
Orowan机制
medium Mn steel
aging
precipitate
composite precipitate
shearing mechanism
Orowan mechanism
