Microstructure Features of Ti-6Al-4V Alloy Deposited by Laser Direct Deposition

Laser direct deposition of fully density metallic components is an advanced technology directly manufacturing metallic components to use a combining technology of rapid prototyping and high power laser cladding. Now researches have indicated that the laser direct deposition of titanium components is most definitely applied domain for this technology, and particularly obvious economic effects can be achieved in the field of manufacturing titanium aerial components. The present paper directs toward the laser direct deposition of Ti-6Al-4V alloy analyzed pattern features of molten pool and microstructure features of single-track build, multi-tracks overlap build, packing build. Through analysis, the bonding condition between cladding track and substrate has been disclosed, and the microstructure features in as-deposited zone and heat-affected zone have been indicated, as well as the influence of the overlap rate, track number of the multi-track overlap, and manner of the packing build on as-deposited microstructures has been explained.

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Effects of Processing Conditions on Laser Direct Deposited Alumina Ceramics

Volume 1: Additive Manufacturing; Advanced Materials Manufacturing; Biomanufacturing; Life Cycle Engineering; Manufacturing Equipment and Automation ◽

10.1115/msec2020-8260 ◽

2020 ◽

Author(s):

John M. Pappas ◽

Xiangyang Dong

Keyword(s):

Grain Size ◽

Processing Parameters ◽

Thin Wall ◽

Processing Conditions ◽

Single Track ◽

Alumina Ceramics ◽

Direct Deposition ◽

Average Grain Size ◽

Scan Speed ◽

Laser Direct Deposition

Abstract Additive manufacturing (AM) of high-quality inherently brittle ceramics via laser direct deposition, also known as laser engineered net shaping, is challenging due to high thermal gradients, thermally induced cracks, and porosity, typically accompanied by low powder usage efficiency. It is necessary to have an improved understanding of the effects of processing conditions on the fabricated ceramic parts. In this study, alumina ceramics were fabricated with commercial alumina powders. In particular, this paper studied the effect of laser power and scan speed on single track geometries, thin-wall morphology, grain size, density, and powder efficiency during laser direct deposition of alumina ceramics. A single-track parametric study was first conducted to determine the range of processing parameters that produce quality single-tracks and to aid in matching the z-increment with layer thicknesses. The results showed that increased scan speeds promoted significant grain refinement. Average grain size was reduced by nearly 50% when scan speed was increased from 1000 mm/min to 5000 mm/min. On the other hand, densification reached a maximum of 98% at a scan speed of 1000 mm/min with a slight decrease in density was observed at higher speeds. This indicated a trade-off between porosity and grain size when altering the laser scan speed. Significant advantages of using CO2 lasers for AM of ceramics was also demonstrated with powder usage efficiencies reaching nearly 90% under optimized processing conditions.

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