IF钢晶体取向与纳米力学性能的原位分析

In-situ analysis of crystal orientation and nano-mechanical property of IF steel

为了研究材料微区力学性能与多晶体取向之间的直接定量联系,以IF钢(无间隙原子钢)为例,分析了不同晶体取向与纳米力学性能之间的关系。首先利用高温激光扫描共聚焦显微镜(HLSM)对IF钢样品进行退火处理,以保证原位分析的有效性,然后通过电子背散射衍射(EBSD)对退火前后的标定区域进行晶体取向分析,得出晶体取向的原位变化规律,最后利用纳米压痕仪测试标定区域的微观力学性能。结果表明,不同晶体取向晶粒的杨氏模量不同,在原子间距较小的<111>晶体学方向上,杨氏模量值较高,在原子间距较大的<001>晶体学方向上,杨氏模量值较低,并通过理论计算验证了试验结果。退火后,不同晶体取向的晶粒硬度没有明显的规律性,但晶粒内位错密度显著降低,硬度比冷轧态明显下降,随着退火温度的升高,硬度降低速度变缓。

In order to investigate the direct quantitative relationship between mechanical property and polycrystal orientation of the micro zone of materials,the interstitial free（IF）steel was selected as an example to analyze the relationship between crystal orientation and nano-mechanical property.Firstly,high-temperature laser scanning confocal microscope（HLSM）was employed for the annealing treatment of IF steel samples to guarantee the validity of in-situ analysis.Then electron back scattering diffraction（EBSD）was used for crystal orientation analysis of targeted zone before and after annealing to obtain the in-situ change rule of crystal orientation.Finally the micro-mechanical property of targeted zone was tested by nanoindentor.The results showed that the Young′s modulus of the grains with different crystal orientations was different.The Young′s modulus value was relative high in〈111〉crystallographic direction with small interatomic distance,while the Young′s modulus value was low in 〈001〉 crystallographic direction with large interatomic distance.The testing results were verified by theoretical calculation.The hardness of grains with different crystal orientation had no obvious rules after annealing.However,the dislocation density in grains decreased significantly and the hardness decreased obviously compared to the cold-rolling state.The decreasing rate of hardness slowed down with the increase of annealing temperature.