Measurement of melt pool dynamics in stationary laser welding using inline coherent imaging (Conference Presentation)

2019 ◽  
Author(s):  
Troy R. Allen ◽  
Faleh AlTal ◽  
Brian J. Simonds ◽  
James M. Fraser
Keyword(s):  
Laser Welding ◽  
Coherent Imaging ◽  
Melt Pool ◽  
Inline Coherent Imaging

scholarly journals Automatic laser welding and milling with in situ inline coherent imaging

2014 ◽  
Vol 39 (21) ◽  
pp. 6217 ◽  
Author(s):  
P. J. L. Webster ◽  
L. G. Wright ◽  
Y. Ji ◽  
C. M. Galbraith ◽  
A. W. Kinross ◽  
...  
Keyword(s):  
Laser Welding ◽  
Coherent Imaging ◽  
Inline Coherent Imaging

A Study on Laser Welding of Titanium and Stainless Steel

2018 ◽  
Author(s):  
Angshuman Chattopadhyay ◽  
Gopinath Muvvala ◽  
Vikranth Racherla ◽  
Ashish Kumar Nath
Keyword(s):  
Stainless Steel ◽  
Laser Welding ◽  
Weld Joint ◽  
Welding Speed ◽  
Fusion Process ◽  
Longitudinal Stress ◽  
Transverse Cracks ◽  
Cooling Rates ◽  
Melt Pool ◽  
Longitudinal Cracks

Joining of dissimilar metals and alloys has been envisioned since a long time with specific high end applications in various fields. One such combination is austenitic stainless steel grade SS304 and commercial grade titanium, which is very difficult to join under conventional fusion process due to extensive cracking and failure caused by mismatch in structural and thermal properties as well as formation of the extremely brittle and hard intermetallic compounds. One of the methods proposed in literature to control the formation of intermetallics is by fast cooling fusion process like laser beam welding. The present study has been done on laser welding of titanium and stainless steel AISI 304 to understand the interaction of these materials during laser welding at different laser power and welding speed which could yield different cooling rates. Two types of cracks were observed in the weld joint, namely longitudinal cracks and transverse cracks with respect to the weld direction. Longitudinal cracks could be completely eliminated at faster welding speeds, but transverse cracks were found little influenced by the welding speed. The thermal history, i.e. melt pool lifetime and cooling rate of the molten pool during laser welding was monitored and a relation between thermo-cycle with occurrence of cracks was established. It is inferred that the longitudinal cracks are mainly due to the formation of various brittle intermetallic phases of Fe and Ti, which could be minimized by providing relatively less melt pool lifetime at high welding speeds. The reason of the transverse cracks could be the generation of longitudinal stress in weld joint due to the large difference in the thermal expansion coefficient of steel and titanium. In order to mitigate the longitudinal stress laser welding was carried out with a novel experimental arrangement which ensured different cooling rates of these two metals during laser welding. With this the tendency of transverse cracks also could be minimized significantly.

Porosity Formation after the Irradiation Termination of Laser

2013 ◽  
Vol 800 ◽  
pp. 201-204
Author(s):  
Wang Hong ◽  
Ling Yun Wang ◽  
Ri Sheng Li
Keyword(s):  
Surface Tension ◽  
Laser Welding ◽  
Continuous Wave ◽  
Laser Beams ◽  
Formation Mechanisms ◽  
Volume Of Fluid Method ◽  
Porosity Formation ◽  
Mode Laser ◽  
Melt Pool ◽  
Solidification Processes

Porosity is formed because of the keyhole collapse. The porosity formation is associated with the melt pool dynamics, the keyhole collapse and solidification processes. The objective of the paper is t to investigate porosity formation mechanisms and fluid flow in the melt pool using the volume of fluid method. The results indicate that the formation of porosity in continuous wave keyhole mode laser welding is associated to keyhole collapse, backfilling of liquid metal close the gas exit of the laser welding keyhole, surface tension of the gas/liquid interface play an important role in the backfilling downward to the keyhole right after laser beams left.Keywords: porosity; keyhole; collapse; welding; model

Melt-pool and keyhole dynamics during thin-plate laser welding of steel

1993 ◽  
Author(s):  
K. Williams ◽  
William O'Neill ◽  
William M. Steen
Keyword(s):  
Laser Welding ◽  
Thin Plate ◽  
Melt Pool ◽  
Keyhole Dynamics

Robust High-Speed Melt Pool Measurements for Laser Welding with Sputter Detection Capability

2007 ◽  
pp. 476-485 ◽  
Author(s):  
Nicolaj C. Stache ◽  
Henrik Zimmer ◽  
Jens Gedicke ◽  
Alexander Olowinsky ◽  
Til Aach
Keyword(s):  
Laser Welding ◽  
High Speed ◽  
Detection Capability ◽  
Melt Pool

Tracking and controlling the morphology evolution of 3D powder-bed fusion in situ using inline coherent imaging

2020 ◽  
Vol 32 ◽  
pp. 100978 ◽  
Author(s):  
Tristan G. Fleming ◽  
Stephen G.L. Nestor ◽  
Troy R. Allen ◽  
Mark A. Boukhaled ◽  
Nathan J. Smith ◽  
...  
Keyword(s):  
Morphology Evolution ◽  
Powder Bed Fusion ◽  
Coherent Imaging ◽  
Powder Bed ◽  
Inline Coherent Imaging
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