Effect of Grain Boundary Segregation of Interstitial Elements on Hall–Petch Coefficient in Steels
Effect of Grain Boundary Segregation of Interstitial Elements on Hall–Petch Coefficient in Steels
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DOI：
10.2320/matertrans.ma201314
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发表时间：
2014
影响因子：
1.2
通讯作者：
S. Takaki;Daichi Akama;Nobuo Nakada;T. Tsuchiyama
中科院分区：
文献类型：
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作者：
S. Takaki;Daichi Akama;Nobuo Nakada;T. Tsuchiyama
利用Hall-Petch关系研究了无间隙钢和低碳钢在不同C、N含量下的屈服行为。无间隙钢的Hall-Petch系数只有150MPa·µm 1/2，但加入60ppm的溶质碳后，Hall-Petch系数增大到600MPa·µm 1/2。氮对霍尔-佩奇系数的影响不显著。三维（3D）原子探针分析结果表明，碳的偏析电位是氮的3-4倍。氮对钢中Hall-Petch系数的影响较小可能是由于氮的偏析电位较小。当晶粒细化强化使屈服应力与摩擦应力之差增大时，就会发生不连续屈服；当初次位错堆积在晶界时，就会发生位错发射。在晶界处偏析的碳原子似乎起到了稳定晶界位错发射位的作用，从而提高了铁的Hall-Petch系数。这些结果支持了解释多晶金属屈服的位错堆积模型。(doi: 10.2320 / matertrans.MA201314)
The yielding behavior of interstitial-free steels and low-carbon steels with varying amounts of C and N were investigated in connection with the HallPetch relation. The HallPetch coefficient is as small as 150MPa·µm 1/2 in interstitial-free steels but it increases to 600MPa·µm 1/2 by adding solute carbon up to 60ppm. Nitrogen does not have a significant effect on the HallPetch coefficient. The results of three-dimensional (3D) atom probe analysis indicated that carbon has 34 times greater segregation potential in comparison with nitrogen. The small effect of nitrogen on the HallPetch coefficient in steel is probably due to the small segregation potential of nitrogen. It was also confirmed that discontinuous yielding occurs when the difference between the yield stress and friction stress is increased by grain-refinement strengthening and that yielding occurs by dislocation emission from grain boundaries where primary dislocations have piled up. Carbon atoms segregated at grain boundaries seem to play a role in stabilizing dislocation emission sites at the grain boundaries, which enhances the HallPetch coefficient of iron. These results support the dislocation pile-up model of explaining yielding in polycrystalline metals. [doi:10.2320/matertrans.MA201314]