Energy Transfer Modes in Pulsed Laser Seam Welding

Chelladurai, A. M.; Gopal, K.A.; Murugan, S.; Venugopal, S.; Jayakumar, T.

doi:10.1080/10426914.2014.965829

Cited by 25 publications

(9 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The longitudinal GB and relevant crack at the center of molten track are similar to the laser welding process as observed in Ref. [34]. Notably, the molten track observed in Fig.…”

Section: Grain Boundary Growth Behavior Of Crackssupporting

confidence: 78%

Cracking Behavior in Additively Manufactured Pure Tungsten

Wang

et al. 2018

Acta Metall. Sin. (Engl. Lett.)

View full text Add to dashboard Cite

In this study, near fully dense (96.5%) pure tungsten bulks were additively manufactured and the cracking behavior was investigated. A crack network with a spacing of * 100 lm was observed in the fabricated bulks. It was observed that the laser scanning strategy, which could tailor the microstructure, affected the crack distribution pattern in fabricated tungsten. The calculated surface temperature difference (7300 K) was much higher than the cracking criterion (800 K) of tungsten, indicating that cracking is almost inevitable in laser additive manufacturing of tungsten. It could be concluded that crack network formed because the cracks emerged in every laser molten track and then interconnected in the layer-by-layer building process.

show abstract

“…The longitudinal GB and relevant crack at the center of molten track are similar to the laser welding process as observed in Ref. [34]. Notably, the molten track observed in Fig.…”

Section: Grain Boundary Growth Behavior Of Crackssupporting

confidence: 78%

Cracking Behavior in Additively Manufactured Pure Tungsten

Wang

et al. 2018

Acta Metall. Sin. (Engl. Lett.)

View full text Add to dashboard Cite

show abstract

“…This feature can more readily be seen in the aspect ratio (LWeld/WWeld) as shown in Figure 5b. The flattening of the aspect ratio is a sign of the transition from conduction and keyhole welds, which has also been observed previously 27 .…”

Section: A Weld Cross-sectionsupporting

confidence: 84%

Time-Resolved Absorptance and Melt Pool Dynamics during Intense Laser Irradiation of a Metal

et al. 2018

View full text Add to dashboard Cite

This work of the U.S. Government is not subject to U.S. copyright. I. AbstractHigh irradiance lasers incident on metal surfaces create a complex, dynamic process through which the metal can rapidly change from highly reflective to strongly absorbing. Absolute knowledge of this process underpins important industrial laser processes like laser welding, cutting, and metal additive manufacturing. Determining the time-dependent absorptance of the laser light by a material is important, not only for gaining a fundamental understanding of the light-matter interaction, but also for improving process design in manufacturing. Measurements of the dynamic optical absorptance are notoriously difficult due to the rapidly changing nature of the absorbing medium. This data is also of vital importance to process modelers whose complex simulations need reliable, accurate input data; yet, there is very little available. In this work, we measure the time-dependent, reflected light during a 10 ms laser spot weld using an integrating sphere apparatus. From this, we calculate the dynamic absorptance for 1070 nm wavelength light incident on 316L stainless steel. The time resolution of our experiment (< 1 µs) allows for the determination of the precise conditions under which several important physical phenomena occur, such as melt and keyhole formation. The average absorptances determined optically were compared to calorimetrically-determined values, and it was found that the calorimeter severely underestimated the absorbed energy due to mass lost during the spot weld. Weld nugget cross-sections are also presented in order to verify our interpretation of the optical results, as well as provide experimental data for weld model validation. II.Figure 1: a. Optical profilometry data and cross section of a sample representative of that used in this study. b. Optical microscope image of same location as used in a.

show abstract

“…Laser processing conditions that promote FZ with a depth/width ratio smaller than 0.4 are classified as conduction mode [31]. This mode, characterized by a shallower and wider FZ, shows greater stability of the melting pool [32] and is more adequate for coating purposes. All FZs obtained using energy densities in the 24-65 J/mm 2 range (not shown here) exhibited the conduction mode, including that shown in Figure 2.…”

Section: Morphological Structural and Microstructural Characterizationmentioning

confidence: 99%

Less-rigid coating in Ti obtained by laser surface alloying with Nb

Carvalho

Sallica-Leva

Encinas

et al. 2018

Surface and Coatings Technology

View full text Add to dashboard Cite

The fabrication of parts with stiffness gradation specifically designed to attain higher mechanical and/or biomedical performance is receiving increasing scientific and technological interest. This work reports the use of laser surface alloying to introduce Nb into the surface layer of Ti pieces and thus obtain continuous coatings composed of Ti-Nb alloys. By controlling the laser processing parameters, coatings with lower Young`s modulus and higher hardness compared to the substrate, practically free of cracks and with very low porosity were obtained, using energy densities in the range of 24 to 65 J/mm 2. However, compositional heterogeneity mainly due to microsegregation during the solidification process was observed. Increasing the energy density resulted in deeper fusion zones, which increased the substrate fusion and thus decreased the Nb content and produced a coating with a microstructure predominantly composed of α/α' acicular phase. On the other hand, the Nb content of the coatings produced with lower energy densities was high enough (~20-30 % in mass) to (meta)stabilize the less-rigid α'' and β phases, which promoted the highest reductions in the Young`s modulus of the investigated coatings. Besides the lower stiffness, all coatings presented at least twice the hardness of the substrate. Maps of the properties constructed from the nanoindentation results showed that, despite the compositional heterogeneity, homogenous values of Young`s modulus and hardness were attained and *Manuscript Click here to view linked References the change in the interface region was gradual, in agreement with the concept of functionally graded materials.

show abstract

Energy Transfer Modes in Pulsed Laser Seam Welding

Cited by 25 publications

References 23 publications

Cracking Behavior in Additively Manufactured Pure Tungsten

Cracking Behavior in Additively Manufactured Pure Tungsten

Time-Resolved Absorptance and Melt Pool Dynamics during Intense Laser Irradiation of a Metal

Less-rigid coating in Ti obtained by laser surface alloying with Nb

Contact Info

Product

Resources

About