화학공학소재연구정보센터
Thin Solid Films, Vol.453-54, 84-88, 2004
EPMA microanalysis of recast layers produced during laser drilling of type 305 stainless steel
It is fundamentally important to understand the microstructure of the recast layer and its effect on the properties of the drilled holes. In this work, laser drilling for machining small orifices in type 305 stainless steel was carried out using a pulsed Nd:YAG laser with oxygen, argon and nitrogen as assist gases, respectively. In addition to scanning electron microscopy, electron probe microanalysis was specially used to examine the elemental distributions of the recast layers in the laser-drilled holes. It was found that the microstructural morphologies of the recast layers were independent of the assist gases; characterised by a columnar structure of dendrites composed of austenite probably with minor phase of delta-ferrite in the interdendritic regions. However, the nitrogen contents increased in the recast layers in order of oxygen, argon and nitrogen as the assist gases. This was in good agreement with the corrosion performance of the recast layers assessed by electrochemical polarisation testing. (C) 2003 Elsevier B.V. All rights reserved.