Scanning strategies and spacing effect on laser fusion of H13 tool steel powder using high power Nd:YAG pulsed laser

Solidification cracking represents a significant scientific and technical challenge in the rapid fabrication of bimetallic parts involving Cu and H13 tool steel. The main cause of the cracking formation is attributed to the residual stress accumulation, which depends on the thermal history and phase transformation during the deposition. In this research, a thermomechanical three-dimensional finite element model is developed to determine the temperature history and residual stress in Cu-H13 samples deposited by the Laser Engineered Net Shaping (LENS) process. The development of the model was carried out using the SYSWELD software package. The metallurgical transformations are taken into account using the temperature dependent material properties and the continuous cooling transformation diagram. Two different scanning strategies — alternative and unidirectional — are studied. The same model is also applied to a H13-H13 sample to compare the results. The input laser power is optimized for each layer and three different scanning speeds to maintain a steady molten pool size. It is observed that for a constant scanning speed the required laser power decreases with addition of more layers, and with the increase of scanning speed the laser power needs to be increased. The residual stress is found to be compressive near the center of the deposited wall and tensile at the free edges, which is consistent with the published experimental results in the literature. Similar stress distributions are obtained for both scanning strategies with higher stress concentration at the free edges of the interface between the substrate and the first layer. In these regions, the use of H13 substrate results in a higher stress accumulation than the Cu substrate.

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Improvement of Build Speed and Quality of H13 Tool Steel Processed by Laser-Beam Powder Bed Fusion with a High-Power Laser

Journal of the Japan Society of Powder and Powder Metallurgy ◽

10.2497/jjspm.68.415 ◽

2021 ◽

Vol 68 (10) ◽

pp. 415-421

Author(s):

Takashi MIZOGUCHI ◽

Takaya NAGAHAMA ◽

Makoto TANO ◽

Shigeru MATSUNAGA ◽

Takayuki YOSHIMI ◽

...

Keyword(s):

Laser Beam ◽

Tool Steel ◽

High Power ◽

Powder Bed Fusion ◽

High Power Laser ◽

Power Laser ◽

Powder Bed ◽

H13 Tool Steel

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Effect of titanium carbide concentration on the morphology of MC carbides in pulsed laser surface alloyed AISI H13 tool steel

Optics & Laser Technology ◽

10.1016/j.optlastec.2018.11.001 ◽

2019 ◽

Vol 112 ◽

pp. 236-244 ◽

Cited By ~ 13

Author(s):

Ali Dadoo ◽

Seyyed Mohammad Ali Boutorabi ◽

Shahram Kheirandish

Keyword(s):

Titanium Carbide ◽

Tool Steel ◽

Pulsed Laser ◽

Laser Surface ◽

H13 Tool Steel ◽

Aisi H13 ◽

Aisi H13 Tool Steel

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Correlation between pulsed laser parameters and MC carbide morphology in H13 tool steel/TiC composite coating

Optics & Laser Technology ◽

10.1016/j.optlastec.2020.106120 ◽

2020 ◽

Vol 127 ◽

pp. 106120 ◽

Cited By ~ 2

Author(s):

Ali Dadoo ◽

Seyyed Mohammad Ali Boutorabi

Keyword(s):

Composite Coating ◽

Tool Steel ◽

Pulsed Laser ◽

Laser Parameters ◽

H13 Tool Steel ◽

Carbide Morphology

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Raster scan selective laser melting of the surface layer of a tool steel powder bed

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/095440505x32201 ◽

2005 ◽

Vol 219 (4) ◽

pp. 379-384 ◽

Cited By ~ 23

Author(s):

T H C Childs ◽

C Hauser

Keyword(s):

Selective Laser Melting ◽

Tool Steel ◽

Laser Energy ◽

Steel Powder ◽

Beam Diameter ◽

Laser Melting ◽

Powder Bed ◽

H13 Tool Steel ◽

Scan Speed ◽

The Masses

Square areas, 15 mm × 15 mm in size, have been melted in the surface of powder beds made from H13 tool steel, using a raster-scanning CO2 laser focused to a beam diameter of 0.6 mm. Laser powers from approximately 50 to 150 W and scan speeds from 0.5 to 300 mm/s have been used, at two scan spacings, 0.15 mm and 0.45 mm. The appearances of the layers in the different conditions, dense or porous, have been observed by low-magnification scanning electron microscopy. The masses of the layers have been measured and simulations have been carried out to predict the masses. The variation of mass with scan speed, at a constant laser power, has been found to be much less than might be expected from a constant absorptivity of laser energy into the bed. The simulations suggest that absorptivities range from 0.25 to approximately 1.0 and that, during any one scan, heating of the bed by previous scans must be considered in order even partially to explain the observations. The work is relevant to attempts to build metal parts without supports, by selective laser melting.

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