Avoidance of end crater imperfections at high-power laser beam welding of closed circumferential welds

Gook, Sergej; Üstündağ, Ömer; Gumenyuk, Andrey; Rethmeier, Michael

doi:10.1007/s40194-019-00841-x

Cited by 10 publications

(7 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such investigations must be carried out considering thermophysical properties of melt, such as surface tension and viscosity, to allow the laser beam oscillation technique to be transferred to SLM tubes made from nickel-based alloys to eliminate the formation of pores [22,23]. Further tests need to be made to improve the welding quality in the end crater area by defocusing the laser [24]. It can be mentioned positively that there were no hot cracks in the weld seams, despite the materials IN625 and IN718 being often susceptible to them.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Laser Welding of SLM-Manufactured Tubes Made of IN625 and IN718

et al. 2019

Self Cite

View full text Add to dashboard Cite

The advantage of selective laser melting (SLM) is its high accuracy and geometrical flexibility. Because the maximum size of the components is limited by the process chamber, possibilities must be found to combine several parts manufactured by SLM. An application where this is necessary, is, for example, the components of gas turbines, such as burners or oil return pipes, and inserts, which can be joined by circumferential welds. However, only a few investigations to date have been carried out for the welding of components produced by SLM. The object of this paper is, therefore, to investigate the feasibility of laser beam welding for joining SLM tube connections made of nickel-based alloys. For this purpose, SLM-manufactured Inconel 625 and Inconel 718 tubes were welded with a Yb:YAG disk laser and subsequently examined for residual stresses and defects. The results showed that the welds had no significant influence on the residual stresses. A good weld quality could be achieved in the seam circumference. However, pores and pore nests were found in the final overlap area, which meant that no continuous good welding quality could be accomplished. Pore formation was presumably caused by capillary instabilities when the laser power was ramped out.

show abstract

Section: Discussionmentioning

confidence: 99%

“…Further tests need to be made to improve the welding quality in the end crater area by defocusing the laser [24].…”

Section: Discussionmentioning

confidence: 99%

Laser Welding of SLM-Manufactured Tubes Made of IN625 and IN718

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…Bakir et al [27] and Kadoi et al [9] demonstrated an on-line/in situ monitoring system of the susceptibility to hot cracking during welding, applicable to laser beam welding. It is possible to make both longitudinal and circumferential joints ensuring the tightness of the joint [28], which is needed at the container. In special cases, two sources are combined to take advantage of their advantages, creating hybrid laser-arc welding [29][30][31].…”

Section: Requirements For the Ferrofluid Containermentioning

confidence: 99%

Laser welding of austenitic ferrofluid container for the KRAKsat satellite

Janiczak

Pańcikiewicz

2021

Weld World

View full text Add to dashboard Cite

The production of a ferrofluid container, intended for use in the KRAKsat (CubeSat type) satellite in space conditions, is presented. Mechanized laser beam welding for AISI 316L stainless steel test joint and container prototype was developed and tested. The welded test joints were examined by non-destructive visual, penetration and radiographic testing and destructive testing by macro- and microscopic examination, static tensile test, static bending test, and hardness measurements. The welded container prototype was examined by leak test, temperature-vacuum test and vibration test. Test joints’ evaluation showed a proper selection of welding parameters and expected quality of joints. Austenitic microstructure with small δ-ferrite content in base materials, heat-affected zones, and welds guarantees sufficient mechanical properties for this part geometry. The tensile strength range of test joints was 687–729 MPa, hardness range was 140–200 HV3, and the bending angle was 180°. Welding of the prototype container and testing of tightness, resistance to temperature changes, and vibration were successful. Compliance with flywheel design and manufacturing requirements will enable the launch of a research satellite into orbit with such a wheel.

show abstract

“…In recent studies on the mitigation of laser termination defects in autogenous laser keyhole welding of 8-mm-thick sections, Gook et al have investigated both laser power rampdown and laser defocusing termination methods [17]. The authors show that the transition from full penetration to partial penetration welding is prone to root sagging or solidification crack defects when either laser power ramp-down or laser defocusing is applied.…”

Section: Introductionmentioning

confidence: 99%

“…The main applications of laser defocusing are for post-weld laser treatment purposes, such as laser surface remelting to improve the weld topology, microstructure, and mechanical properties. The "smoothing layer" shown by Gook et al [17] is an example. Further examples were shown by Powell et al for improving the weld root uniformity [18] and Xu et al to try and reduce the weld hardness and improve the weld surface profile [19].…”

Section: Introductionmentioning

confidence: 99%

Study of the effect of inter-pass temperature on weld overlap start-stop defects and mitigation by application of laser defocusing

Lai

Ganguly

Suder

2021

Int J Adv Manuf Technol

View full text Add to dashboard Cite

Laser keyhole initiation and termination-related defects, such as cracking and keyhole cavities due to keyhole collapse, are a well-known issue in laser keyhole welding of thick section steels. In longitudinal welding, run-on and run-off plates are used to avoid this problem. However, such an approach is not applicable in circumferential welding where start/stop defects remain within the workpiece. These issues can hinder industry from applying laser keyhole welding for circumferential welding applications. In this paper, the effect of inter-pass temperature on laser keyhole initiation and termination at the weld overlap start-stop region was investigated. This study has identified that defects occurring within this region were due to laser termination rather than laser initiation because of keyhole instabilities regardless of the thermal cycle. The laser termination defects were mitigated by applying a laser defocusing termination regime to reduce the keyhole depth gradually and control the closure of the keyhole.

show abstract

Avoidance of end crater imperfections at high-power laser beam welding of closed circumferential welds

Cited by 10 publications

References 14 publications

Laser Welding of SLM-Manufactured Tubes Made of IN625 and IN718

Laser Welding of SLM-Manufactured Tubes Made of IN625 and IN718

Laser welding of austenitic ferrofluid container for the KRAKsat satellite

Study of the effect of inter-pass temperature on weld overlap start-stop defects and mitigation by application of laser defocusing

Contact Info

Product

Resources

About