A NEW PREPARATION TECHNIQUE OF SURFACE TO MICROSTRUCTURAL EXAMINATIONOF HEAT RESISTING STEELS AND ALLOYS BY USING PENNING DISCHARGE MICRO-SPUTTERING

The microstructure oi heat resisting steels and alloys for high-temper ature plants changes depending on operating conditions and time. The m icrostructural changes affect the mechanical properties of the materia ls at high temperatures. Microstructural examination of the materials is generally carried out using etching techniques by chemical method. For chemical etching, however. high skill is required to produce clear microstructure. In this research, penning discharge micro-sputtering techniques were applied for etching a variety of heat resisting steels and a super alloy. The etching of 1Cr-1Mo-0.25V ferritic and 316H aus tenitic steels and Ni-base Inconel 713C superalloy was carried out in the vacuum chamber of a micro-sputtering apparatus. All oi the materia ls exhibited clear microstructure using micro-sputtering, irrespective of different chemical compositions and different history of the mater ials. The grain boundaries, creep voids and precipitates such as carbi des and a phase were characterized. It was concluded that the present method required lesss skill and the resultant microstructure was insen sitive to sputtering conditions.