The Paton Welding Journal, 2026, №09

2026 №09 (05)

DOI of Article 10.37434/tpwj2026.09.06

2026 №09 (07)

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The Paton Welding Journal, 2026, #9, 56-63 pages

Influence of laser spot diameter on track formation and melt pool penetration in LPBF-process of 316L steel

S.V. Adzhamskyi^1,2, R.V. Podolskyi^1,3,4, T.V. Balakhanova³, O.E. Baranovskaya³, S.I. Badyuk^1,4, N.P. Togobytska⁵

¹LLC “Additive Laser Technology of Ukraine” 31v Serhiy Podolynskyi Str., 49000, Dnipro, Ukraine
²Institute of Transport Systems and Technologies of the NASU 5 Pysarzhevskyi Str., 49000, Dnipro, Ukraine
³Z.I. Nekrasov Iron and Steel Institute of the NASU 1 Akad. Starodubova Squ., 49000, Dnipro, Ukraine E-mail: rostislavpodolskij@gmail.com
⁴Institute of Applied Control Systems of the NASU 42 Akad. Glushkova Prosp., 03187, Kyiv, Ukraine
⁵HTW University of Applied Sciences 8 Triskovallie Str., 10318, Berlin, Germany

Abstract
This study systematically investigates the influence of key laser powder bed fusion (LPBF) process parameters, namely laser spot diameter, laser power, and scanning speed, on the crystallization front geometry of single tracks produced in 316L austenitic stainless steel. Particular attention was paid to evaluating the effect of laser spot diameter. Experimental investigations were performed using a laser processing system equipped with ytterbium fiber lasers featuring a Gaussian beam profile. Single-track experiments were conducted over a wide range of processing conditions, with laser power varying from 150 to 500 W, scanning speed from 700 to 1000 mm/s, and laser spot diameter from 75 to 175 μm. The results demonstrated that the highest track continuity and process stability were achieved with a 75 μm laser spot diameter combined with a laser power of 175‒200 W and a scanning speed of 1000 mm/s. Increasing the laser spot diameter over 125 μm required a significant increase in laser power to maintain stable melting, accompanied by a noticeable reduction in track stability. At a spot diameter of 175 μm, capillary instability and droplet formation were observed even at high laser power and moderate scanning speeds. Further analysis showed that the optimal melt pool depth-to-width ratio exceeding 0.8, characteristic of the keyhole melting mode, was achieved exclusively with the laser spot diameter of 75 μm. In contrast, larger spot diameters produced shallower melt pools, in such a way increasing the probability of defect formation in the final components.
Keywords: LPBF-technology, single track scanning, laser spot diameter, scanning process parameters

Received: 26.07.2026
Received in revised form: 27.04.2026
Accepted: 24.09.2026

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Suggested Citation

S.V. Adzhamskyi, R.V. Podolskyi, T.V. Balakhanova, O.E. Baranovskaya, S.I. Badyuk, N.P. Togobytska (2026) Influence of laser spot diameter on track formation and melt pool penetration in LPBF-process of 316L steel. The Paton Welding J., 09, 56-63. https://doi.org/10.37434/tpwj2026.09.06

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