A1 Journal article (refereed), original research

Filler Metal Mixing Behaviour of 10 mm Thick Stainless Steel Butt-Joint Welds Produced with Laser-Arc Hybrid and Laser Cold-Wire Processes


Publication Details
Authors: Karhu Miikka, Kujanpää Veli, Eskelinen Harri, Salminen Antti
Publication year: 2019
Language: English
Related Journal or Series Information: Applied sciences
Volume number: 9
Issue number: 8
Start page: 1
End page: 21
Number of pages: 21
eISSN: 2076-3417
JUFO-Level of this publication: 1
Open Access: Not an Open Access publication

Abstract

In thick section laser welding, filler metal addition is usually required to improve jointfit-up tolerances or to control the chemical composition of the weld metal. With deep and narrowwelds produced using an over-alloyed filler metal, it may be challenging to ensure that the fillermetal and its elements are homogeneously mixed and evenly distributed throughout the fusionzone. Inhomogeneous filler metal mixing can cause unfavourable changes to weld metal chemistryand microstructure. Filler metal mixing behaviour in laser-arc hybrid and laser cold-wire weldingis studied in this work. Welding tests were conducted on 10 mm thick butt-welded joints of AISI316L austenitic stainless steel. An overmatching type 2205 duplex stainless steel filler wire wasused to obtain a composition contrast between the base metal and filler metal. Energy dispersivespectroscopy (EDS) with chromium as the trace element was used for element mapping and stepwisecharacterization of the weld cross-section samples. Optical metallography was used to observepossible inhomogeneous filler metal mixing behaviour like local acute changes in macro- andmicrostructural features. The results showed a clear difference in filler metal mixing between theweld surface part (upper half) of the weld and the weld root part (lower half) in 10 mm thick weldedcross-sections for closed root gap of I-groove welds or when the gap was only 0.4 mm. In narrowI-groove preparations, inhomogeneous mixing phenomena were more pronounced in laser cold-wirewelds than in laser-arc hybrid welds. In both welding processes, a combination of trailing wirefeeding and the use of a wider groove enabled filler metal to be introduced deeper into the bottom ofthe groove and improved mixing in the root portion of the welds.


Last updated on 2020-20-03 at 10:03