Purpose: of this paper was to analyze the influence of the basic parameters of laser
welding (i.e. laser beam power and welding speed, as well as energy input) of butt joints of
the 2.0 mm thick stainless steel AISI 304 sheets on the weld shape and joint quality.
Design/methodology/approach: The preliminary trials of simulated laser welding by
melting the austenitic stainless steel sheets (the so called bead-on-plate welding), as
well as the welding of the test butt joints, were carried out using the high-power diode
laser (HPDL) ROFIN DL 020, without the additional material (the technique of autogenous
welding). A crucial parameter that determines both the mechanical properties and the
corrosive resistance of a joint (the region of a weld and HAZ - heat affected zone) in the
case of stainless steels with austenitic structure is energy input, which should be kept at a
minimum, and at the same time full penetration and a proper shape of the fusion zone should
be ensured. The investigations included the macrostructure and microstructure observations
by light microscopy, researches of mechanical properties in a static tensile test and also
microhardness measurements made by Vickers method.
Findings: The results have shown that it is possible to provide a proper shape of the weld
of fine-grained structure and narrow heat affected zone, but it requires careful selection of
the welding parameters, especially a low energy input. The microhardness measurements
showed that the in case of welding the butt joints using the high-power diode laser in HAZ
area a slight increase in microhardness to approx. 185HV0.2 compared to base material
(160-169HV0.2) and a decrease in microhardness in the fusion zone (FZ) to approx. 140-
150HV0.2 have been observed. All welded sample broke from the joint during the testing at
tensile stress between 585 MPa and 605 MPa with corresponding percentage elongation in
the range of 45-57%. It can be found that the joints strength is not less than the strength of
the base metal of 2.0 mm thick AISI 304 austenitic stainless steel sheet.
Research limitations/implications: Studies of the weldability of stainless steels indicate
that the basic influence on the quality of welded joints and reduction of thermal distortions
has the heat input of welding, moreover the highest quality of welded joints of austenitic
stainless steel sheets are ensured only by laser welding.
Practical implications: The laser welding technology can be directly applied for welding
of austenitic steel AISI 304 sheets 2.0 mm thick.
Originality/value: Application of high power diode laser for welding of austenitic stainless
steel AISI 304.
MICROSTRUCTURAL INHOMOGENEITY OF PHASE COMPOSITION AND GRAIN STRUCTURE IN ELECTRON BEAM WIRE-FEED ADDITIVE MANUFACTURED AISI 304 STAINLESS STEEL
