TY - THES A1 - Shcheglov, Pavel T1 - Study of Vapour-Plasma Plume during High Power Fiber Laser Beam Influence on Metals N2 - Die wichtigsten Ergebnisse der Dissertation sind: 1. Experimentelle Untersuchungen der Dampf-Plasma-Fackel wurden beim Schweißen von niedriglegierten Stählen großer Blechdicke unter Einsatz der Strahlung eines Hochleistungsfaserlasers (10÷20 kW) durchgeführt. 2. Experimentell wurde festgestellt, dass die Temperatur sowie die Volumenkonzentration der freien Elektronen im laserinduzierten Schweißplasma vernachlässigbar gering sind (Т < 4500 К, n < 1015e cm -3). 3. Es wurde gezeigt, dass neben dem Schweißplasma, das mit einem relativ kleinen Volumen (5-10 mm) nahe der Metalloberfläche entsteht, die Schweißfackel einen größeren Teil (bis 60-70 mm) im oberen Bereich einnimmt, welcher aus der Wolke der kleinen Partikel aus kondensiertem Metalldampf besteht und die Laserstrahlung absorbieren kann. 4. Die experimentell gemessene durchschnittliche Größe der kondensierten Metallpartikel in der Schweißfackel beträgt je nach Fackelhöhe bzw. Schweißprozessparameter 80 nm bis 110 nm. Die Volumenkonzentration der Partikel in der Wolke an der Fackelachse beträgt ca. 1010 cm-3. 5. Die Extinktion der Prüfstrahlung im oberen Teil der Schweißfackel wird zum großen Teil von der Absorption der kleinen kondensierten Partikel verursacht. Der experimentell gemessene Extinktionskoeffizient für eine Prüfstrahlungswellenlänge von 1.3 μm hatte einen Wert von etwa einigen m-1 und ist damit wesentlich größer als der Koeffizient der inversen Bremsstrahlungsabsorption im Schweißplasma. 6. Schutzgaszufuhr (Ar, He) beim Schweißprozess führt zur effektiven Abkühlung des Schweißplasmas im unteren Teil der Fackel bis zur vollen Unterdrückung. Infolge des intensiveren Kondensationsprozesses über der Dampfkapillare kann aber dabei der Einfluss des oberen Teiles noch stärker werden. 7. Die Gesamtleistungsabschwächung des Hochleistungsfaserlaserstrahls, der durch die Schweißfackel zur Metalloberfläche gelangt, kann variierend einen Wert von bis zu 10% haben. Mit Rücksicht auf die zeitliche Dynamik kann dieser Effekt zu einer erheblichen Verschlechterung der Leistungsstabilität der Laserstrahlung führen, die den Dampfkapillareeingang erreicht. N2 - The most important results of the dissertation are: 1. Systematic experimental investigations of the vapour-plasma plume generated during deep penetration high-power (10÷20 kW) ytterbium fiber laser beamwelding of low-alloyed mild steel plates were carried out. 2. It was confirmed experimentally that free electron temperature and concentration in the laser- induced welding plasma plume are negligibly low (Т < 4500 К,ne < 10 15 cm-3). On the basis of these values it can be affirmed that absorption and refraction of high power fiber laser radiation in the welding plasma plume are not able to influence the welding quality in this case. 3. It was shown that the vapour-plasma welding plume is composed of the welding plasma generated in a relatively small area (5-10 mm height) near the metal surface and of an extensive upper part (up to 60-70 mm height) which consists of a small condensed metal vapour particle cloud and is able to absorb electromagnetic radiation. 4. Average condensed metal vapour particle diameter in the welding plume was measured experimentally to vary from 80 nm to 110 nm depending on the welding plume height as well as on the welding process parameters. Volume particle concentration in the cloud on the welding plume axis has a value of about 1010 cm-3. 5. Extinction of the probe laser radiation in the upper part of the welding plume is mainly caused by absorption in the small condensed metal vapour particles. The extinction coefficient at the probe radiation wavelength of 1.3 μm was measured experimentally to have a value of about a few units per meter which is much higher than the inverse Bremsstrahlung absorption coefficient in the welding plasma plume calculated for this radiation wavelength. 6. Shielding gas (Ar or He) supplied to the welding area leads to intensive cooling of the welding plasma in the lower part of the welding plume down to its complete suppression. However, due to the more intensive metal vapour condensation process in the colder medium above the keyhole, the upper part influence can become even stronger. 7. Total attenuation of the high-power fiber laser beam propagating through the whole welding plume height to the metal surface was estimated to be about 10%. Considering the spatial dynamics of the probe light extinction signals it was concluded that the effect of metal vapour condensation over the keyhole during deep penetration high-power fiber laser metal welding is able to significantly worsen of the laser beam power stability when the beam reaches the keyhole inlet. T3 - BAM Dissertationsreihe - 88 KW - Particle diagnostics KW - Plume KW - Plasma diagnostics KW - Laser welding KW - Vapour condensation PY - 2012 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-703 SN - 978-3-9815134-3-1 SN - 1613-4249 VL - 88 SP - 1 EP - 125 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-70 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shcheglov, Pavel A1 - Gumenyuk, Andrey A1 - Gornushkin, Igor B. A1 - Rethmeier, Michael T1 - Experimental investigation of the laser-plume interaction during high power fiber laser welding N2 - The effect of the well-known plasma absorption and refraction in CO2-laser metal welding plumes is in case of high power solid state laser welding negligibly small. By contrast, the diffraction effects of shorter wavelength laser radiation are considerable. According to the results of preliminary studies, the fine condensed metal particles in the welding plume can lead to essential worsening of the laser beam quality. This work is devoted to the investigation of the lasermatter interaction during up to 20 kW ytterbium fiber laser welding of thick mild steel plates. The plume attenuation of a probe 1.3 µm wavelength diode laser beam as well as of continuous radiation in 250-600 nm wavelength range was measured during welding with and without Ar shielding gas supply. The measured results allow it to calculate average size and concentration of fine condensed metal particles in different plume areas using the multi-wavelength method and the Mie scattering theory. The plume temperature, which determines the condensation conditions, was measured by means of Fe I atom spectral line emission registration. The obtained results can be also of interest for remote metal treatment with high-power fiber or disc lasers. T2 - 30th ICALEO - International congress on applications of lasers & electro-optics CY - Orlando, FL, USA DA - 2011-10-23 PY - 2011 SN - 978-0-912035-94-9 SP - Paper 1606, 637 EP - 645 AN - OPUS4-24921 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Petrovskii, V.N. A1 - Uspenskii, S.A. A1 - Shcheglov, Pavel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Investigation of a vapor-plasma welding torch induced by a high-power ytterbium fiber laser KW - Laser welding KW - Condensation KW - Diagnostic of the torch PY - 2011 SN - 2079-5629 VL - 2 IS - 2 SP - 159 EP - 165 PB - MAIK Nauka AN - OPUS4-24811 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shcheglov, Pavel A1 - Uspenskii, S.A. A1 - Gumenyuk, Andrey A1 - Petrovskii, V.N. A1 - Rethmeier, Michael A1 - Yermachenko, V. M. T1 - Plume attenuation of laser radiation during high power fiber laser welding N2 - The results of an in-situ plume-laser interaction measurement during welding of mild steel with a 5 kW ytterbium fiber laser are reported. A measurement of the attenuation of probe laser beam passing through the plume has allowed to estimate the plume characteristics like the size of the extinction area and the spatial distribution of the extinction coefficient. The power loss of the fiber laser radiation propagating through the whole plume length was calculated. Together with a measured temporal characteristics of extinction the result indicates a significant decreasing of the laser radiation stability, which can lead to the formation of the macroscopic welding defects. KW - Laser welding KW - Plume KW - Beam attenuation KW - Particles PY - 2011 DO - https://doi.org/10.1002/lapl.201110010 SN - 1612-2011 VL - 8 IS - 6 SP - 475 EP - 480 PB - Wiley-VCH CY - Berlin AN - OPUS4-24812 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shcheglov, Pavel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael A1 - Petrovskiy, V. T1 - Condensed metal particles influence on the process of high power fiber laser thick metal welding T2 - 22th International Conference "Laser in Science, Technology, Medicine" CY - Gelendzhik, Russia DA - 2011-09-20 PY - 2011 AN - OPUS4-24769 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shcheglov, Pavel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael A1 - Uspenskiy, S. A1 - Petrovskiy, V. A1 - Yermachenko, V. M. T1 - Influence of the welding plume on laser rediation during high power fiber laser welding T2 - 20th International Laser Physics Workshop LHPYS`11 CY - Sarajevo, Bosnia and Herzegovina DA - 2011-07-11 PY - 2011 AN - OPUS4-24770 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shcheglov, Pavel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Plume investigation during high power fiber laser welding T2 - The Fifth International Conference "Laser TEchnologies in Welding and Materials Processing" CY - Crimea, Ukraine DA - 2011-05-24 PY - 2011 AN - OPUS4-24771 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shcheglov, Pavel A1 - Uspenskiy, S. A1 - Petrovskiy, V. A1 - Yermachenko, V. M. T1 - Line and continuum emission spectroscopy of the high power ytterbium fiber laser welding plume under Ar and He shielding atmosphere T2 - 20th International Laser Physics Workshop LHPYS`11 CY - Sarajevo, Bosnia and Herzegovina DA - 2011-07-11 PY - 2011 AN - OPUS4-24772 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Uspenskiy, S.A. A1 - Shcheglov, Pavel A1 - Petrovskiy, V.N. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Spectral diagnostics of a vapor-plasma plume produced during welding with a high-power ytterbium fiber laser N2 - We have conducted spectroscopic studies of the welding plasma formed in the process of welding with an ytterbium fiber laser delivering output power of up to 20 kW. The influence of shielding gases (Ar, He) on different parts of the welding plume is investigated. The absorption coefficient of the laser radiation by the welding-plume plasma is estimated. Scattering of 532-nm probe radiation from particles of the condensed metal vapor within the caustic of a high-power fiber laser beam is measured. Based on the obtained results, conclusions are made on the influence of the plasma formation and metal vapor condensation on the radiation of the high-power fiber laser and the stability of the welding process. PY - 2013 DO - https://doi.org/10.1134/S0030400X13070205 SN - 0030-400X SN - 1562-6911 VL - 115 IS - 1 SP - 140 EP - 146 PB - MAIK Nauka/Interperiodica Publ. / Pleiades Publishing, Ltd. CY - Moscow AN - OPUS4-28983 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael A1 - Shcheglov, Pavel A1 - Uspenskiy, S.A. T1 - SPEKTRAL'NAYa DIAGNOSTIKA PARO-PLAZMENNOGO FAKELA PRI SVARKE MOShchNYM ITTERBIEVYM VOLOKONNYM LAZEROM PY - 2013 DO - https://doi.org/10.7868/S0030403413070209 SN - 0030-4034 VL - 115 IS - 1 SP - 160 EP - 167 PB - Akad. Verl. CY - Moskva [u.a.] AN - OPUS4-29262 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shcheglov, Pavel A1 - Gumenyuk, Andrey A1 - Gornushkin, Igor B. A1 - Rethmeier, Michael A1 - Petrovskiy, V.N. T1 - Vapor-plasma plume investigation during high-power fiber laser welding N2 - This work is devoted to the investigation of the laser–matter interaction during up to 20 kW ytterbium fiber laser welding of thick mild steel plates. The plume attenuation of a probe 1.3 µm wavelength diode laser beam as well as of continuous radiation in the 250–600 nm wavelength range was measured during welding with and without Ar shielding gas supply. The measured results allow the calculation of the average size and concentration of fine condensed metal particles in different plume areas using the multi-wavelength method and the Mie scattering theory. The plume temperature, which determines the condensation conditions, was measured by means of Fe I atom spectral line emission registration. The spatial distribution of the extinction coefficient in the welding plume was measured and the plume attenuation of the high-power fiber laser beam during the welding process was estimated. PY - 2013 DO - https://doi.org/10.1088/1054-660X/23/1/016001 SN - 1054-660X SN - 1531-8494 VL - 23 IS - 016001 SP - 1 EP - 7 PB - MAIK Nauka/Interperiodica Publ. CY - Moscow AN - OPUS4-27280 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shcheglov, Pavel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael A1 - Uspensky, S.A. A1 - Petrovsky, V.N. T1 - Study of welding plume in high-power fiber laser welding T2 - LTWMP '11 - 5th International conference "Laser technologies in welding and materials processing" CY - Crimea, Ukraine DA - 2011-05-24 PY - 2011 SP - 142 EP - 147 AN - OPUS4-25473 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gumenyuk, Andrey A1 - Petrovskiy, V.N. A1 - Rethmeier, Michael A1 - Shcheglov, Pavel A1 - Uspenskiy, S.A. T1 - Condensed metal particles influence during the high power fiber laser welding N2 - Different types of lasers are used nowadays for a number of technological Solutions, Modem high power solid-state lasers with high brightness of Radiation like Fiber or disc lasers find ever more applications in welding technology. Apart from the replacement of the CC>2-iasers traditionaHy used fcr these purposes, they provide new technological possibilities of metal treatment, such as using industrial robots and remote welding with high power laser radiation. The possibility of flexible optical fiber delivery of the radiation to any point gives a great technological advantage and permits welding processes to be realized with complicated weld seam geomelries and different positions using a minimum of additional fixtures. The short wavelength of the high power solid state lasers (1.07 ’m) causes another advantage. The coefflcient of inverse 170 Bremsstrahlung absorption from free electrons in plasma for such radiation is about 100 times lower than for the COi-iaser radiation. Owing to this fact, using the solid state lasers allows it to avoid a negative influence of the welding plume. However, a short wavelength can lead to another kind of laser Radiation attenuation, which is connected with the formation of a cloud consisting of small metal particles that absorb and scatter laser radiation. This cloud arises due to the condensation of hot metal vapor by flying out from the deep Penetration channel and broadening in relatively cold atmosphere over the metal Surface. Some theoretical and experimental approaches were made in advance in Order to estimate the influence of the Condensed particles on laser radiation and welding quality. In this paper a systematic study including the determination of the Cloud size and its dynamical characteristics is presented. The results were obtained within the scope of the first stage of the metal vapor condensation process Investigation during welding with high power fiber lasers. T2 - International Conference 'Lasers in Science, Technology, Medicine' CY - Moscow, Russia DA - 19.09.2011 PY - 2011 VL - 22 SP - 170 EP - 177 AN - OPUS4-29166 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shcheglov, Pavel A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Study of welding plume during high power fiber laser welding T2 - Scientific Session NRNU "MEPhI" 2011 CY - Moscow, Russia DA - 2011-02-01 PY - 2011 AN - OPUS4-23323 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Shcheglov, Pavel A1 - Gumenyuk, Andrey A1 - Gornushkin, Igor B. A1 - Rethmeier, Michael T1 - Experimental Investigation of the Laser-Plume Interaction during High Power Fiber Laser Welding T2 - 30th International Congress on Applications of Laser & Electro-Optics (ICALEO) CY - Orlando, FL, USA DA - 2011-10-23 PY - 2011 AN - OPUS4-24768 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -