Effect of Process Parameters on Both Molten Pool Temperature and Layer Size During Metal Laser Deposition Shaping

Online observation is expected to provide a better understanding of the cathodic cleaning of oxides from the molten pool during variable-polarity gas tungsten arc welding (VP GTAW) of aluminium alloys. In this paper, a machine-vision system with appropriate illumination and filtering is used to monitor in real time the effect of different process parameters on the cleaning of oxides from the molten pool during VP GTAW of Al 6061. Based on the observations, the process conditions under which a clean molten pool can be achieved are determined. In addition, the control of the welding process to maintain the consistency of cathodic cleaning is discussed. The results showed that in order to have an oxide-free molten pool, the solid surface in front of the molten pool should be cleaned from oxides by the electric arc. The choice of process parameters to satisfy this condition has been discussed. It was found that the percentage of direct current electrode positive (DCEP) polarity in the cycle of current has the highest impact on the cathodic cleaning, with the arc current having less influence, and the welding speed showing the least effect. Furthermore, in order to keep the consistency of oxide cleaning, process parameters should be set or controlled to maintain the cleaned zone larger than the molten pool.

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Self-Sufficient Modeling of Single Track Deposition of Ti–6Al–4V With the Prediction of Capture Efficiency

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4041423 ◽

2018 ◽

Vol 141 (1) ◽

Cited By ~ 14

Author(s):

Christopher Katinas ◽

Shunyu Liu ◽

Yung C. Shin

Keyword(s):

Molten Pool ◽

Deposition Process ◽

Capture Efficiency ◽

Laser Deposition ◽

Single Track ◽

Profile Error ◽

Track Geometry ◽

Direct Laser Deposition ◽

Direct Laser ◽

Traditional Manufacturing

Understanding the capture efficiency of powder during direct laser deposition (DLD) is critical when determining the overall manufacturing costs of additive manufacturing (AM) for comparison to traditional manufacturing methods. By developing a tool to predict the capture efficiency of a particular deposition process, parameter optimization can be achieved without the need to perform a costly and extensive experimental study. The focus of this work is to model the deposition process and acquire the final track geometry and temperature field of a single track deposition of Ti–6Al–4V powder on a Ti–6Al–4V substrate for a four-nozzle powder delivery system during direct laser deposition with a LENS™ system without the need for capture efficiency assumptions by using physical powder flow and laser irradiation profiles to predict capture efficiency. The model was able to predict the track height and width within 2 μm and 31 μm, respectively, or 3.3% error from experimentation. A maximum of 36 μm profile error was observed in the molten pool, and corresponds to errors of 11% and 4% in molten pool depth and width, respectively. Based on experimentation, the capture efficiency of a single track deposition of Ti–6Al–4V was found to be 12.0%, while that from simulation was calculated to be 11.7%, a 2.5% deviation.

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Propagation Characteristic of Ultrasonic in BT20 Titanium Alloy and Research on Distribution of Ultrasonic Field in Molten Pool of Laser Deposition Repair

Chinese Journal of Lasers ◽

10.3788/cjl201340.1203009 ◽

2013 ◽

Vol 40 (12) ◽

pp. 1203009 ◽

Cited By ~ 1

Author(s):

杨光 Yang Guang ◽

郭鹏飞 Guo Pengfei ◽

王维 Wang Wei ◽

钦兰云 Qin Lanyun ◽

卞宏友 Bian Hongyou ◽

...

Keyword(s):

Titanium Alloy ◽

Molten Pool ◽

Ultrasonic Field ◽

Propagation Characteristic ◽

Laser Deposition

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Effect of process parameters on defects in large scale components manufactured by direct laser deposition

Materials Today Proceedings ◽

10.1016/j.matpr.2020.01.519 ◽

2020 ◽

Vol 30 ◽

pp. 665-671

Author(s):

D. Masaylo ◽

S. Igoshin ◽

A. Popovich ◽

V. Popovich

Keyword(s):

Process Parameters ◽

Large Scale ◽

Laser Deposition ◽

Direct Laser Deposition ◽

Direct Laser

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The Influence of Process Parameters and Scanning Strategy on Lower Surface Quality of TA15 Parts Fabricated by Selective Laser Melting

Metals ◽

10.3390/met10091228 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1228

Author(s):

Junjie Jiang ◽

Jianming Chen ◽

Zhihao Ren ◽

Zhongfa Mao ◽

Xiangyu Ma ◽

...

Keyword(s):

Surface Quality ◽

Selective Laser Melting ◽

Process Parameters ◽

Flexible Manufacturing ◽

Molten Pool ◽

Lower Surface ◽

Laser Melting ◽

Scanning Strategy ◽

Influence Of Process Parameters

With superior flexible manufacturing capability, selective laser melting (SLM) has attracted more and more attention in the aerospace, medical, and automotive industries. However, the poor quality of the lower surface in overhanging structures is still one of the factors that limits the wide application of SLM. In this work, the influence of process parameters and scanning strategy on the lower surface quality of SLMed TA15 (Ti-6Al-2Zr-1Mo-1V) titanium alloy parts were studied. The results showed that the laser surface energy density (EF) had a significant influence on the quality of the lower surface. Excessive EF led to obvious sinking of the molten pool and a serious slag hanging phenomenon. However, the too low EF easily contributed to the insufficient powder fusion in the lower surface area, which led to the agglomeration of a molten pool during core processing, resulting in slag hanging, pores, and powder spalling that reduced the quality of the lower surface. Moreover, the cross-remelting strategy and non-remelting strategy gained better surface quality at the low EF and high EF, respectively. In addition, it was found that the quality of the lower surface could be quickly and accurately evaluated by the cooling time of the molten pool during the processing of the lower surface. This research can increase the understanding of the forming mechanism of the lower surface and has certain guiding significance for the process optimization of the lower surface.

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Numerical Simulation of Moving Heat Flux during Selective Laser Melting of AlSi25 Alloy Powder

Metals ◽

10.3390/met10070877 ◽

2020 ◽

Vol 10 (7) ◽

pp. 877

Author(s):

Cong Ma ◽

Xianshun Wei ◽

Biao Yan ◽

Pengfei Yan

Keyword(s):

Numerical Simulation ◽

Selective Laser Melting ◽

Process Parameters ◽

Molten Pool ◽

Laser Power ◽

Scanning Speed ◽

Powder Layer ◽

Maximum Temperature ◽

Three Dimensional Model ◽

Laser Melting

A single-layer three-dimensional model was created to simulate multi-channel scanning of AlSi25 powder in selective laser melting (SLM) by the finite element method. Thermal behaviors of laser power and scanning speed in the procedure of SLM AlSi25 powder were studied. With the increase of laser power, the maximum temperature, size and cooling rate of the molten pool increase, while the scanning speed decreases. For an expected SLM process, a perfect molten pool can be generated using process parameters of laser power of 180 W and a scanning speed of 200 mm/s. The pool is greater than the width of the scanning interval, the depth of the molten pool is close to scan powder layer thickness, the temperature of the molten pool is higher than the melting point temperature of the powder and the parameters of the width and depth are the highest. To confirm the accuracy of the simulation results of forecasting excellent process parameters, the SLM experiment of forming AlSi25 powder was carried out. The surface morphology of the printed sample is intact without holes and defects, and a satisfactory metallurgical bond between adjacent scanning channels and adjacent scanning layers was achieved. Therefore, the development of numerical simulation in this paper provides an effective method to obtain the best process parameters, which can be used as a choice to further improve SLM process parameters. In the future, metallographic technology can also be implemented to obtain the width-to-depth ratio of the SLM sample molten pool, enhancing the connection between experiment and theory.

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