Abstract
The microstructures of deposited TC21 titanium alloy with high strength, high toughness and high damage-tolerance by laser rapid forming (LRF) were studied with Optical Microscopy (OM), Scanning Electronic Microscopy (SEM), X-Ray Diffraction (XRD) and micro-hardness test. The results show that the prior β grains in the deposited TC21 are coarse and columnar for the epitaxial growth with some smaller equiaxed β grains in the top of last layer. Macro-image reveals that two different microstructure areas existed in the deposited TC21: the bright area of acicular martensite located in the last more than 10 layers; and the dark area of basket-weave. By the theory of heat flux in the processing and microstructure transformation, it can be concluded that the basket-weave microstructure is transformed from the initial rapid-solidification martensite of bright area through solid solution and aging treatment by reheat cycles during the LRF process. With the increase of the laser power, the prior columnar β grains become coarser and the α lamellaes in the dark area with basket-weave microstructure grow up. Meanwhile, the micro-hardness keeps constant for the bright area, but descends slightly for the dark area.
Original language | English |
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Pages (from-to) | 612-616 |
Number of pages | 5 |
Journal | Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering |
Volume | 36 |
Issue number | 4 |
State | Published - Apr 2007 |
Keywords
- Laser rapid forming
- Micro-hardness
- Microstructures
- TC21 titanium alloy