Name: SERAFIM LUIZ PÊGO JÚNIOR
Publication date: 25/09/2026
Examining board:
Name |
Role |
|---|---|
| ADONIAS RIBEIRO FRANCO JUNIOR | Examinador Externo |
| CARLOS AUGUSTO CARDOSO PASSOS | Presidente |
| MARCOS TADEU D AZEREDO ORLANDO | Examinador Interno |
Summary: Duplex stainless steels combine high mechanical strength and corrosion resistance due to their two-phase microstructure of ferrite and austenite. This study looked at the effect of laser welding on the microstructural, mechanical, and thermal characteristics of Lean Duplex Stainless Steel UNS S32304. The material, supplied in strips 72.0 mm wide and 1.9 mm thick, was characterized before and after welding using optical microscopy, X-ray diffraction (XRD), image analysis, Vickers
microhardness, and thermal diffusivity by Laser Flash Analysis (LFA). The results confirmed the presence of ferrite and austenite, with no evidence of significant formation of harmful phases. The material as received had about 45% austenite and
55% ferrite, while the weld zone showed an increase in the ferrite fraction, reaching around 85% due to the high cooling rates of laser welding. The average thermal diffusivity dropped from about 2.16 × 107 m2/s in the as-received material to values
between 1.39 × 107 and 1.85 × 107 m2/s after welding. The microhardness also changed along the joint, with an average of around 211 HV in the welded condition, compared to 326 HV for austenite and 274 HV for ferrite in the as-received material. It can be concluded that laser welding promoted significant changes in the phase distribution and in the thermal and mechanical properties of UNS S32304, mainly in the fusion zone and the heat-affected zone, without evidence of compromising the stability of the main phases.
Keywords: duplex stainless steel; UNS S32304; laser welding; microstructure; X-ray diffraction; Vickers microhardness; hermal diffusivity.
