Micro-properties of the oxide scale and near-surface zone of a type 316 steel annealed in air and vacuum have been systematically investigated. Microstructures of the specimens have been examined using optical microsc...Micro-properties of the oxide scale and near-surface zone of a type 316 steel annealed in air and vacuum have been systematically investigated. Microstructures of the specimens have been examined using optical microscopy and scanning and transmission electron microscopy (TEM). Chemical compositions for the oxide scale and near surface zone were also analysed. The results obtained show that the oxide scale developed in vacuum exhibits a distinct structure from that developed in air. Comparing to the vacuum-developed scale, the air-developed scale possesses a more complicated structure and relatively poor adhesion to the matrix. TEM observations reveal a difference in the dislocation density in the vicinity of the free surface, near-surface zone and the core of the specimens examined.展开更多
The effect of arc sprayed times, which are quantitatively described by the volume fraction of coatings, on the mechanical properties of type 316 steel, have been undertaken in the present work. Al wires were utilized ...The effect of arc sprayed times, which are quantitatively described by the volume fraction of coatings, on the mechanical properties of type 316 steel, have been undertaken in the present work. Al wires were utilized as coatings materials. Tensile tests were carried out in the temperature range of Portevin-Le Chatelier (PLC) effect It has been found that grains at edges and corners of the 316 steel specimens have been dramatically constricted by grit blasting and spraying. Grit blasting has been found to exert a shot-peening effect on the mechanical properties of 316 steel specimens. Coatings with lower values of coating volume fraction strengthen the coated specimens in the very similar way as blasting. While if the volume fraction of coating, (Vv)c, exceeds a critical value, (VV)K, softens the specimens. Specimens with low values of (Vv)c, have high values of flow stress, as well as higher values of work-hardening coefficient, Calculations based on the experimental results show that the high thickness coatings have relatively lower contribution to the mechanical properties of specimens.展开更多
文摘Micro-properties of the oxide scale and near-surface zone of a type 316 steel annealed in air and vacuum have been systematically investigated. Microstructures of the specimens have been examined using optical microscopy and scanning and transmission electron microscopy (TEM). Chemical compositions for the oxide scale and near surface zone were also analysed. The results obtained show that the oxide scale developed in vacuum exhibits a distinct structure from that developed in air. Comparing to the vacuum-developed scale, the air-developed scale possesses a more complicated structure and relatively poor adhesion to the matrix. TEM observations reveal a difference in the dislocation density in the vicinity of the free surface, near-surface zone and the core of the specimens examined.
文摘The effect of arc sprayed times, which are quantitatively described by the volume fraction of coatings, on the mechanical properties of type 316 steel, have been undertaken in the present work. Al wires were utilized as coatings materials. Tensile tests were carried out in the temperature range of Portevin-Le Chatelier (PLC) effect It has been found that grains at edges and corners of the 316 steel specimens have been dramatically constricted by grit blasting and spraying. Grit blasting has been found to exert a shot-peening effect on the mechanical properties of 316 steel specimens. Coatings with lower values of coating volume fraction strengthen the coated specimens in the very similar way as blasting. While if the volume fraction of coating, (Vv)c, exceeds a critical value, (VV)K, softens the specimens. Specimens with low values of (Vv)c, have high values of flow stress, as well as higher values of work-hardening coefficient, Calculations based on the experimental results show that the high thickness coatings have relatively lower contribution to the mechanical properties of specimens.
