Laser Welding of AZ31B Magnesium alloy in a Lap Joint configuration

• Research Objectives

  	Power (W)
  Surface condition	800	900	1000	1100
  As received
  Chemically treated (10 min.)
  Mechanically removed	No Weld	No Weld
  Plasma treated

  • Evaluate the feasibility of achieving the sound lap joint of AZ31B magnesium alloy sheets by a high power fiber laser.
  • Develop an optimal processing parameter window for a laser welding of AZ31B alloy.
• Issues in Welding of Magnesium Alloys
  • Porosity
    • Pre-existing pores
    • Chromate on surface
    • Hydrogen pores
    • Collapse of unstable keyhole
    • Evaporation of elements
  • Cracking
    • Large freezing temperature range
    • Large solidification shrinkage
    • High coefficient of thermal expansion
    • Low melting point intermetallic constituents
• Mitigating the effect of chromate 
  • Chemically treated (10 min.)
  • Mechanically removed
  • Plasma preheated
• Summary
  • Defect-free lap joints of AZ31B magnesium alloy in a lap joint configuration are achieved by combining a plasma arc with a single laser beam.
  • Mechanical property tests including microhardness and tensile-shear test are carried out for the different pre-treatment techniques.