Influence of process parameters and initial microstructure on the oxidation resistance of Ti48Al2Cr2Nb coating obtained by laser metal deposition

Ti6Al4V has been recognized as an attractive material, due to its combination of low density and favorable mechanical properties. However, its insufficient oxidation resistance has limited the high-temperature application. In this work, an AlCoCrFeNiTi0.5 high-entropy alloy (HEA) coating was fabricated on a Ti6Al4V substrate using laser metal deposition (LMD). The microstructure and isothermal oxidation behaviors were investigated. The microstructure of as-deposited HEA exhibited a Fe, Cr-rich A2 phase and an Al, Ni, Ti-enriched B2 phase. Its hardness was approximately 2.1 times higher than that of the substrate. The oxidation testing at 700 °C and 800 °C suggested that the HEA coating has better oxidation resistance than the Ti6Al4V substrate. The oxide scales of the Ti6Al4V substrate were mainly composed of TiO2, while continuous Al2O3 and Cr2O3 were formed in the HEA coatings and could be attributed to oxidation resistance improvement. This work provides an approach to mitigate the oxidation resistance of Ti6Al4V and explore the applicability of the HEA in a high-temperature environment.

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Experimental Investigation of Temperature Distribution during Wire-Based Laser Metal Deposition of the Al-Mg Alloy 5087

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.988 ◽

2018 ◽

Vol 941 ◽

pp. 988-994 ◽

Cited By ~ 3

Author(s):

Martin Froend ◽

Frederic E. Bock ◽

Stefan Riekehr ◽

Nikolai Kashaev ◽

Benjamin Klusemann ◽

...

Keyword(s):

Process Parameters ◽

Large Scale ◽

Substrate Material ◽

Metal Deposition ◽

Temperature Evolution ◽

Laser Metal Deposition ◽

Deposition Rates ◽

Excessive Heat ◽

Manufacturing Techniques ◽

The Individual

Wire-based laser metal deposition enables to manufacture large-scale components with deposition rates significant higher compared to powder-based laser additive manufacturing techniques, which are currently working with deposition rates of only a few hundred gram per hour. However, the wire-based approach requires a significant amount of laser power in the range of several kilowatts instead of only a few hundred watts for powder-based processes. This excessive heat input during laser metal deposition can lead to process instabilities such as a non-uniform material deposition and to a limited processability, respectively. Although, numerous possibilities to monitor temperature evolution during processing exist, there is still a lack of knowledge regarding the relationship between temperature and geometric shape of the deposited structure. Due to changing cooling conditions with increasing distance to the substrate material, producing a wall-like structure results in varying heights of the individual tracks. This presents challenges for the deposition of high wall-like structures and limits the use of constant process parameters. In the present study, the temperature evolution during laser metal deposition of AA5087 using constant process parameters is investigated and a scheme for process parameter adaptions in order to reduce residual stress induced componential distortions is suggested.

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Melt Pool Temperature Control for Laser Metal Deposition Processes—Part I: Online Temperature Control

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4000882 ◽

2010 ◽

Vol 132 (1) ◽

Cited By ~ 37

Author(s):

Lie Tang ◽

Robert G. Landers

Keyword(s):

Temperature Control ◽

Process Parameters ◽

Process Model ◽

Dynamic Balance ◽

Metal Deposition ◽

Time Varying ◽

Laser Metal Deposition ◽

Melt Pool ◽

Melt Pool Temperature ◽

Deposition Processes

Melt pool temperature is of great importance to deposition quality in laser metal deposition processes. To control the melt pool temperature, an empirical process model describing the relationship between the temperature and process parameters (i.e., laser power, powder flow rate, and traverse speed) is established and verified experimentally. A general tracking controller using the internal model principle is then designed. To examine the controller performance, three sets of experiments tracking both constant and time-varying temperature references are conducted. The results show the melt pool temperature controller performs well in tracking both constant and time-varying temperature references even when process parameters vary significantly. However a multilayer deposition experiment illustrates that maintaining a constant melt pool temperature does not necessarily lead to uniform track morphology, which is an important criteria for deposition quality. The reason is believed to be that different melt pool morphologies may have the same temperature depending on the dynamic balance of heat input and heat loss.

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