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Title: Crystal growth during keyhole mode laser welding

Authors:
; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1397867
Grant/Contract Number:
NE0008280
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 133; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 22:23:36; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English

Citation Formats

Wei, H. L., Elmer, J. W., and DebRoy, T.. Crystal growth during keyhole mode laser welding. United States: N. p., 2017. Web. doi:10.1016/j.actamat.2017.04.074.
Wei, H. L., Elmer, J. W., & DebRoy, T.. Crystal growth during keyhole mode laser welding. United States. doi:10.1016/j.actamat.2017.04.074.
Wei, H. L., Elmer, J. W., and DebRoy, T.. Sat . "Crystal growth during keyhole mode laser welding". United States. doi:10.1016/j.actamat.2017.04.074.
@article{osti_1397867,
title = {Crystal growth during keyhole mode laser welding},
author = {Wei, H. L. and Elmer, J. W. and DebRoy, T.},
abstractNote = {},
doi = {10.1016/j.actamat.2017.04.074},
journal = {Acta Materialia},
number = C,
volume = 133,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on May 22, 2018
Publisher's Accepted Manuscript

Citation Metrics:
Cited by: 2works
Citation information provided by
Web of Science

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  • A novel approach to simulating the dominant dynamic processes present during concentrated energy beam welding of metals is presented. A model for transient behavior of the front keyhole wall is developed. It is assumed that keyhole propagation is dominated by evaporation recoil-driven melt expulsion from the beam interaction zone. Results from the model show keyhole instabilities consistent with experimental observations of metal welding, metal cutting and ice welding.
  • Keyhole plasma arc welding is a unique arc welding process for deep penetration. To ensure the quality of the welds, the presence of the keyhole is critical. Understanding of the keyhole will certainly benefit the improvement of the process and weld quality. Currently, the size of the keyhole is assumed to be correlative with the robustness of the keyhole process in maintaining the keyhole. To verify this assumption, the keyhole and the weld pool were simultaneously monitored from the back side of the workpiece. It was found that once the keyhole is established, the width of the keyhole does notmore » change with an increasing welding current and a decreasing welding speed. This implies the width of the keyhole gives no adequate information about the stable state of the keyhole and should not be used as an indication of the robustness of the keyhole process in plasma arc welding.« less
  • In the laser welding of metals with a continuous CO{sub 2} laser, a hole containing a partially ionized metal vapor is formed throughout the depth of the material. A full description of flow conditions inside this hole is needed for a complete understanding of the process, but much can be learned from a simpler analysis of this aspect of the problem. The balance of forces that keeps the keyhole open can be investigated in this way. Such a model shows that over most of the keyhole`s length, the dominant force keeping the keyhole open against surface tension is the fluidmore » mechanical pressure in the plasma rather than the ablation pressure. This has a bearing on the problem of the formation of pores in the interior of the welded material. It is clearly observable on films made of the surface of the weld piece and of cross-sections through it that the keyhole has some of the characteristics of instability. It is shown that under some circumstances the balance of pressure against the forces of surface tension can be sufficiently great for cavities within the molten material to be formed. Estimates can then be made for the spacing of these cavities.« less
  • We observed, with an x-ray apparatus, the keyhole formed during the interaction of a pulsed Nd{endash}YAG laser beam with a metallic target of a Ti{endash}6Al{endash}4V titanium alloy. We noted that the keyhole formation is not instantaneous and that it grows linearly during the duration of the interaction. We highlighted that its depth, at the end of the laser pulse, is practically equal to the melting-zone depth in the material. Finally, we showed from the results of these tests that a quick estimation of the melting depth can be made simply from the ratio of the power densities used with amore » reference test. {copyright} 2001 American Institute of Physics.« less
  • The model developed allows one to know the temperature field in a cw Nd:YAG laser joining piece. To realize the model, a physical approach has been used for defining the heat sources. First, from a pressures balance the geometry of the keyhole is determined. Then, an analysis of the plume existing at the surface of the target shows that the beam is scattered by the plume and consequently the heated area is enlarged. More a spectrometric characterization indicates that no ionized particles exist in the plume and certainly in the keyhole. So Fresnel absorptions are the predominant effects for energymore » absorption in the keyhole. This assumption is verified owing to Fresnel absorption coefficient measurements.« less