Characterisation of local grain size variation of welded structural steel

Pauli Lehto*, Jani Romanoff, Heikki Remes, Teemu Sarikka

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

30 Citations (Scopus)
200 Downloads (Pure)


Previously, it has been shown that the grain size distribution plays an important role in the mechanical properties of welded steel. In the previous investigation, the volume-weighted average grain size has been shown to capture the influence of grain size distribution, resulting in a better fitting Hall–Petch relationship between grain size and hardness. However, the previous studies exclude the effects arising from local variation in grain size. In this paper, the grain size measurement methods are extended for the characterisation of the local grain size variation, which is significant for welded joints and can have an adverse effect on mechanical properties. The local gradient of grain size variation and its dependency on measurement direction are considered. In addition, examples of grain size and hardness variation are shown for S355 base metal and two weld metals, and characteristic differences are highlighted and discussed. The coarse-grained areas of a heterogeneous microstructure are found to have lower hardness than fine-grained areas. However, the surrounding microstructure, i.e. local grain size gradient, has an influence on the measured hardness values.

Original languageEnglish
Pages (from-to)673-688
Number of pages16
JournalWelding in the World
Issue number4
Early online date22 Mar 2016
Publication statusPublished - 1 Jul 2016
MoE publication typeA1 Journal article-refereed


  • Grain size
  • Hardness
  • Measurement
  • Microstructure
  • Structural steels
  • Weld metal


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