Characterization of AZ31B wrought magnesium alloy joints welded by high power fiber laser

Journal Article · Sat Oct 15 04:00:00 EDT 2011 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2011.07.002· OSTI ID:22066335

Zemin, Wang; Haiguo, Tang; Xiaoyan, Zeng

A 6 kW fiber laser is used to weld AZ31B wrought magnesium alloy and the characterization of welded joints are studied by the observations of bead size, microstructure and mechanical properties. The accepted joints without macro-defects can be obtained when the laser power is in the range of 2.5 to 4.0 kW. Typical hexagonal dendrites are observed in the fusion zone, whose average semi-axis length increases with increasing heat input or decreasing welding speed. The minimum ultimate tensile strength of welded joints reaches 227 MPa, 94.6% of the base metal. And when the heat input reduces to 48 J/mm or lower, the joints are fractured in the base metal, showing stronger failure strength compared to the base metal. For the joints ruptured in the weld metal, the fracture surface is characterized by a ductile-brittle mixed pattern consisting of both dimples and cleavages. Finally, the formation mechanism of pore in the welds is discussed and summarized by the pore morphologies on the fracture surface. - Highlights: {yields} Accepted joints of AZ31B Mg alloy are produced by high power fiber laser. {yields} Optimal welding parameters are summarized by experimental observations. {yields} Obvious hexagonal dendrites are observed in the fusion zone. {yields} The joints are stronger than base metal as the heat input is lower than 48 J/mm. {yields} Pore formation mechanism of welded joints is discussed and summarized.

• OSTI ID: 22066335
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Journal Issue: 10 Vol. 62; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CLEAVAGE
DENDRITES
FRACTURES
HEXAGONAL LATTICES
LASER WELDING
MAGNESIUM ALLOY-AZ31B
MORPHOLOGY
SURFACES
TENSILE PROPERTIES
WELDED JOINTS