Growth morphologies and primary solidification modes in a dissimilar weld between a low-alloy steel and an austenitic stainless steel

Fanny Mas, Catherine Tassin, François Roch, Miguel Yescas, Patrick Todeschini, Yves Bréchet

Research output: Contribution to journalArticleResearchpeer-review

15 Citations (Scopus)

Abstract

Dissimilar welds close to the fusion boundary exhibit a variety of solidification microstructures that strongly impact their service behavior. Investigations were therefore undertaken to clarify the origins of the morphological and microstructural evolutions encountered in a 18MND5/309L dissimilar joint produced by submerged arc welding, using a combination of microstructural characterizations, thermodynamic computations, and solidification modelling. An unexpected evolution was observed in the solidification mode, from primary austenite towards primary ferrite with increasing growth rate. Solidification of austenite at the fusion boundary was assigned to its epitaxial growth on the metastable austenitic structure of the base metal resulting from an incipient melting mechanism. The evolution of the solidification mode toward primary ferrite was explained based on computations of the solute built up between austenite cells followed using the so-called “interface response function model”. Analyzing macro-and microstructural characteristic lengths with the published solidification model and data enabled evaluation of local values of the solidification rate, thermal gradient, and cooling rate close to the fusion boundary, thus providing useful data for numerical modelling of the submerged arc-welding process.

Original languageEnglish
Article number284
Number of pages21
JournalMetals
Volume8
Issue number4
DOIs
Publication statusPublished - 19 Apr 2018
Externally publishedYes

Keywords

  • Dissimilar steel welds
  • Epitaxial growth
  • Incipient melting
  • Solidification microstructure
  • Thermokinetic modelling
  • Welding

Cite this