High resolution microstructural studies of the evolution of nano-scale, yttrium-rich oxides in ODS steels subjected to ball milling, selective laser melting or friction stir welding

As compared to normal Friction Stir Welding (FSW) joints, the Underwater Friction Stir Welding (UFSW) has been reported to be obtainable in consideration of enhancement in mechanical properties. A 5052-Aluminum Alloy welded joints using UFSW method with plate thickness of 6 mm were investigated, in turn to interpret the fundamental justification for enhancement in mechanical properties of material through UFSW. Differences in microstructural features and mechanical properties of the joints were examined and discussed in detail. The results indicate that underwater FSW has reported lower hardness value in the HAZ and higher hardness value in the intermediate of stir zone (SZ). The average hardness value of underwater FSW increases about 53% greater than its base material (BM), while 21% greater than the normal FSW. The maximum micro-hardness value was three times greater than its base material (BM), and the mechanical properties of underwater FSW joint is increased compared to the normal FSW joint. Besides, the evaluated void-area fraction division in the SZ of underwater FSW joint was reduced and about one-third of the base material (BM). The approximately estimated average size of the voids in SZ of underwater FSW also was reduced to as low as 0.00073 mm2, when compared to normal FSW and BM with approximately estimated average voids size of 0.0024 mm2 and 0.0039 mm2, simultaneously.

Download Full-text

Dispersion of CNTs in Selective Laser Melting Printed AlSi10Mg Composites via Friction Stir Processing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.879.1915 ◽

2016 ◽

Vol 879 ◽

pp. 1915-1920 ◽

Cited By ~ 6

Author(s):

Zheng Lin Du ◽

Ming Jen Tan ◽

Jun Feng Guo ◽

Jun Wei ◽

Chee Kai Chua

Keyword(s):

Selective Laser Melting ◽

Friction Stir Processing ◽

Laser Melting ◽

Metal Composites ◽

Friction Stir ◽

Zener Pinning ◽

Pinning Effect ◽

Dendritic Network ◽

Vicker’S Microhardness ◽

Particulate Reinforced

The superior elastic modulus, stiffness and wear resistance of particulate-reinforced metal composites (MMCs) have drawn much attention in various industries ranging from defence, aerospace and automobile industries. Here, friction stir processing (FSP) has successfully dispersed carbon nanotubes (CNTs) and significantly reduced cavities in selective laser melting (SLM) fabricated AlSi10Mg-CNTs composites. Further grain refinement, was achieved via FSP with the addition of CNTs. This is mainly attributed to the dynamic recrystallization and Zener pinning effect. The addition of CNTs to AlSi10Mg resulted in significant improvement in hardness of SLM fabricated aluminium composites. However, FSP of these samples resulted in reductions in the Vicker’s microhardness. This could be due to the dissolution of hardening precipitates and the absences of fine dendritic network present in SLM fabricated parts.

Download Full-text