The effect of laser, Hybrid Laser-Tungsten inert gas (HLT) and Hybrid Laser-Metal inert gas (HLM) welding processes on the microstructure and mechanical properties of 5.6 mm thick 316L(N) stainless...

Laser and hybrid laser welding of type 316L(N) austenitic stainless steel plates

A pathway to mitigate macrosegregation of laser-arc hybrid Al-Si welds through beam oscillation

Determination of optimum hybrid laser–TIG welding process variables for achieving the maximum depth of penetration (DOP) in type 316LN stainless steel has been carried out using a genetic algorithm (GA). Nd:YAG pulsed laser and the TIG heat source were coupled at the weld pool to carry out hybrid welding. Design of experiments approach was used to generate the experimental design matrix. Bead-on-plate welds were carried out based on the design matrix. The input variables considered were laser power, pulse frequency, pulse duration, and TIG current. The response variable considered was the DOP. Multiple-regression model was developed correlating the process variables with the DOP using the generated data. The regression model was used for evaluating the objective function in GA. GA-based model was developed and it produced a set of solutions. Tournament and roulette wheel selection methods were used during the execution of GA. It was found that both the selection methods identified similar welding ...

Optimization of hybrid laser–TIG welding of 316LN stainless steel using genetic algorithm

Investigation on microstructure and mechanical properties of NV E690 steel joint by laser-MIG hybrid welding

In the heat-treated condition, 18% Ni maraging steels have a microstructure of aged martensite and essentially no austenite. However, austenite can form if the material is overaged. This has been termed as austenite reversion, a subject which has received much attention, because it importantly influences properties and performance of the steel. Reversion of austenite in fusion zones of weld joints in these steels has also been widely studied. Because of microsegregation, austenite reversion in the fusion zone is accelerated. Reverted austenite in the fusion zone strongly influences the performance of the weld joints. The present review critically analyses the published work on austenite reversion and its effects on properties and performance, covering both base metal and weld joints.

Austenite reversion in 18% Ni maraging steel and its weldments

Maraging steel 250 grade plates of 10 mm thickness were welded in single pass using a laser-arc hybrid welding (LHW) setup comprising 3.5 kW CO2 laser and synergic pulse metal inert gas (MIG) welding power source at a welding speed of 1 m/min. The influence of single-pass welding on the bead characteristics, microstructure, and mechanical properties was investigated. The size and volume fraction of reverted austenite was effectively reduced in the fusion zone. Moreover, the width of the heat-affected zones (HAZ) was reduced and the microhardness results did not show significant softening in the HAZ after post weld aging. Tensile testing of the welds in transverse direction showed 97.3% weld efficiency. The fusion zone exhibited KIc fracture toughness of 77.4 MPa√m which was affected by the distribution pattern of reverted austenite. The study vividly brings out the process advantages of LHW for accomplishing thick section welds of maraging steel in single pass with narrow groove and lesser filler wire con...

Single Pass Laser-Arc Hybrid Welding of Maraging Steel Thick Sections

The present work is directed towards understanding the role of filler addition in laser-MIG hybrid welding (LHW) process as compared with that in autogenous laser welding (ALW) process during welding of 10-mm-thick maraging steel plates. Addition of filler wire is beneficial in improving the edge bridging between the parts to be welded and also in improving the fusion zone microstructure. Single-pass LHW of the 10-mm-thick maraging steel plates was performed using a combination of 3.5-kW CO2 laser and synergic pulse MIG welding power source at a welding speed of 1 m/min. MIG filler wire with reduced solutes such as Mo and Ti contents was used for the LHW process. Simultaneously, double-sided single-pass ALW of similar plates was performed. The role of filler wire addition on the microstructure and mechanical properties of the LHW fusion zone (FZ) was studied and compared with that of ALW FZ. The usage of filler wire resulted in less solutes in the LHW FZ after welding, and hence, the volume fraction of “reverted austenite (RA)” formed during aging was minimized when compared with ALW FZ. During transverse weld tensile testing, the ALW welds yielded higher tensile properties when compared with the LHW weld due to their fine grain structure and high number density of precipitates. Whereas the KIc fracture toughness of the ALW FZ was low with the KIc value of 49.5 MPa√m due to the presence of the high amount of RA as compared with LHW which exhibited the KIc value of 77.5 MPa√m. The study vividly brings out the advantages of LHW process in improving the microstructure of the fusion zone due to the addition of filler wire.

Swati Ghosh

Papers

Single Pass Laser-Arc Hybrid Welding of Maraging Steel Thick Sections

Comparison of laser-MIG hybrid and autogenous laser welding of M250 maraging steel thick sections—understanding the role of filler wire addition