Effect of laser welding on the mechanical and degradation behaviour of Fe-20Mn-0.6C bioabsorbable alloy

Abstract

The present work aims at exploring the influence of laser welding on the functional behaviour of a Fe-20Mn-0.6C (wt.%) bioabsorbable alloy. At first, the selection of the most suitable process speed (40 mm/s) was done in order to obtain a full penetration joint with limited taper. Then, microstructural and mechanical analyses of welded sheets confirmed suitable performance of the joint, without porosity, thus preserving chemical composition, mechanical resistance and ductility even after welding. In particular, the base material comprised both γ austenite and ε martensite, while the welded samples showed a further type of martensite, namely α’. Moreover, ultimate tensile strength (1095 MPa and 1104 MPa in base and welded material, respectively) and elongation to failure (61.3% and 60.9%, respectively) were almost not influenced by the welding process. Considering the absorbable nature of these alloys, static immersion degradation tests were carried out, and confirmed that the surface of the welded bead did not exhibit a significant variation of the material degradation rate after 14 days in modified Hanks’ solution. Finally, a significant accumulation of degradation products, mainly (Fe,Mn)CO3, was observed along the joining line.

Keywords

• Bioabsorbable metallic compounds
• Laser welding
• Fe-Mn alloys
• Microstructure
• Mechanical properties
• In vitro degradation