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Root formation and mechanical properties in laser keyhole welding of 15 mm thick HSLA steel

Abstract

Deep penetration laser welding is promising in joining thick (> 10 mm) steel sections. Focused laser beam by drilling vapour cavity, the keyhole, generates deep and narrow welds. Full penetration single-pass joining has a persistent problem with root quality where humping is one of the most frequent imperfection. This strongly hampers the use of high-power laser for thick plate welding. A 16 kW disk laser was used for single-pass welding of 15 mm thick plates in a butt joint configuration. Root humping occurred within a wide range of welding parameters. This provides narrow processing window. By adding an arc source to the laser beam process, the tendency of root humping increases. To achieve humping-free welds and consistent root quality over length, a delicate balance of process parameters is required. High heat input (> 0.50 kJ/mm) was positive to achieve a combination of low hardness (< 325 HV) and good Charpy toughness at -50 °C (> 50 J).
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Category

Academic article

Language

English

Author(s)

Affiliation

  • SINTEF Industry / Materials and Nanotechnology
  • Denmark
  • Finland
  • Norwegian public roads administration

Year

2021

Published in

IOP Conference Series: Materials Science and Engineering

ISSN

1757-8981

Volume

1135

View this publication at Norwegian Research Information Repository