Pompeo G, Girasole M, Longo G, Cricenti A, Bailo D, Ronci F, Maras A, Serracino M, Moretti P F
Istituto di Struttura della Materia, CNR, via del Fosso del Cavaliere 100, 00133, Rome, Italy.
J Microsc. 2008 May;230(Pt 2):218-23. doi: 10.1111/j.1365-2818.2008.01978.x.
The aim of this study is to investigate the nanocrystallization of steels caused by the transformation from the austenitic to the martensitic phase induced by a severe plastic deformation (SPD) treatment. In this framework, we applied an air blast shot peening treatment, which is a simple protocol widely used for industrial purposes.
AISI 286 and AISI 316 specimens were peened for different times and polished using diamond pastes in order to remove corrugations higher than 1 mum. The characterization of the steel surfaces was performed by atomic force microscopy (AFM) operating in contact mode. Additional EDXD measurements were performed to confirm the phase transition.
An AFM-based characterization at nanometric level of the steel surfaces is provided. When the peening exceeds a threshold time that, as expected, depends on the steel composition, a uniform nanostructuration is detected. It is well known that such rearrangement is associated to the growth of a martensitic phase. To date, AFM has been employed in this field only for few applications and to solve specific problems. On the other hand, our results demonstrate that this is a useful technique for the characterization of hardened surfaces, especially when non-destructive sample preparation treatments are required. Moreover, we show that AFM can be a useful tool also for in situ industrial diagnostics of metallic parts.
本研究的目的是调查由严重塑性变形（SPD）处理诱导的从奥氏体相向马氏体相转变所引起的钢的纳米晶化。在此框架下，我们应用了鼓风喷丸处理，这是一种广泛用于工业目的的简单工艺。
对AISI 286和AISI 316试样进行不同时间的喷丸处理，并用金刚石研磨膏进行抛光，以去除高于1微米的波纹。通过以接触模式操作的原子力显微镜（AFM）对钢表面进行表征。进行了额外的能量色散X射线衍射（EDXD）测量以确认相变。
提供了基于AFM对钢表面进行纳米级表征的结果。当喷丸时间超过一个阈值时间时（正如预期的那样，该阈值时间取决于钢的成分），会检测到均匀的纳米结构化。众所周知，这种重新排列与马氏体相的生长有关。迄今为止，AFM在该领域仅用于少数应用并解决特定问题。另一方面，我们的结果表明，这是一种用于表征硬化表面的有用技术，特别是在需要进行无损样品制备处理时。此外，我们表明AFM也可以成为金属部件原位工业诊断的有用工具。
