Influence of Laser Beam Wobbling Parameters on Microstructure and Properties of 316L Stainless Steel Multi Passed Repaired Parts

Abstract

The results of experimental studies of repair of the supporting structure components made of 316L steel multi-pass laser cladding with filler wire are presented. The influence of the wobbling mode parameters, welding speed, and laser power on the formation of the deposited metal during multi-pass laser cladding with filler wire of 316L steel samples into a narrow slot groove, 6 mm deep and 3 mm wide, are shown. Non-destructive testing, metallographic studies, and mechanical tests of the deposited metal before and after heat treatment (2 h at 450 °C) were carried out. Based on the results of experimental studies, the optimal modes of laser beam wobbling were selected (amplitude—1.3 mm, frequency—100 Hz) at which the formation of a bead of optimal dimensions (height—1672 μm, width—3939 μm, depth of penetration into the substrate—776 μm) was ensured. A laser cladding technology with ESAB OK Autrode 316L filler wire has been developed, which has successfully passed the certification for conformity with the ISO 15614-11 standard. Studies of the chemical elements’ distribution before and after heat treatment showed that, after heat treatment along the grain boundaries, particles with a significantly higher Mo content (5.50%) were found in the sample, presumably precipitated phases. Microstructure studies and microhardness measurements showed that the upper part metal of the third pass, which has a lower microhardness (75% of base metal), higher ferrite content, and differently oriented dendritic austenite, significantly differs from the rest of the cladded metal.

Effect of Y2O3 Content on Microstructure and Wear Resistance of Laser Cladding Layer of Stellite-6 Alloy

“…The temperature gradient in the middle of the fusion coating was small, the undercooling increased, and the dilution rate had little effect, resulting in the generation of a large number of cellular crystals. The top tissue had the fastest cooling rate due to its minimum temperature gradient, proximity to the surface, and the blowing effect of the protected gas [20]. Moreover, the rare earth element Y acted as a heterogeneous nucleation point in the coating, thus forming a large number of equiaxed crystals and small network crystals.…”

Laser metal deposition repair of stainless steel 316L parts

“…This peak is approximately 400 µm thick on each side. For the HAZ, this increase in hardness can be explained by the formation of delta ferrite, which has a higher plasticity than austenite and causes an increase in hardness [160,181]. For the fusion zone near the interface, Balit et al [101] explained the presence of a peak of hardness by the finer microstructure of the bead in contact with the substrate and related it to the epitaxial growth of the bead grains on the substrate grains during solidification.…”