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Control of solid-state phase transformations during the wire arc additive manufacturing process to reduce residual stress and deformation in deposits

Arnoulin, Pauline; Bertrand, Emmanuel; Couturier, Laurent; Gloaguen, David; Girault, Baptiste; Lee, Tung Lik; Kelleher, Joe; Morville, Simon; Courant, Bruno

Abstract

The heating and cooling conditions during the wire arc additive manufacturing process (WAAM) generate complex thermal, metallurgical and mechanical phenomena that induce stresses and strains within the part. They are mainly due to incompatibilities between local deformations induced by thermal expansion gradients. In steels, certain phase transformations, between ferrite, austenite and martensite, can also interfere with the state of stress and strain. To reduce residual stresses and strains, we propose to control solid-state phase transformations, through local chemical composition, to drive metallurgical deformations that counter thermal distorsions. To that end, we study the various phase transformations arising from the martensitic, austenitic and ferritic stainless steels combinations. The microstructure of the 12 alloys produced in situ are analysed and related to the deformation and residual stress state, measured by neutron diffraction, to reveal their correlations. Phase evolution has been shown to have a significant influence on the stress establishment in the part, with up to 66% less strain depending on the transformations encountered. These results enable us to identify the chemical compositions for which we obtain the least deformation and stress, and therefore the microstructures to be favoured. Finally, this study paves the way for the development of functionally graded materials produced by WAAM for improved final properties.

Full text

AAMS 2025 Control of solid-state phase transformations during the wire arc additive manufacturing process to reduce residual stress and deformation in deposits Pauline Arnoulin1,2,3, Emmanuel Bertrand3, Laurent Couturier3, David Gloaguen2, Baptiste Girault2, Tung Lik Lee4, Joe Kelleher4, Simon Morville1, Bruno Courant2 1IRT Jules Verne - Nantes Université, Institut de Recherche Technologique Jules Verne, programme PERFORM, F44340 Bouguenais, France 2GeM - Nantes Université, Ecole Centrale Nantes, CNRS, Institut de Recherche en Génie Civil et Mécanique, GeM, F-44600 Saint-Nazaire, France 3IMN - Nantes Université, CNRS, Institut des Matériaux de Nantes Jean Rouxel, IMN, F 44000 Nantes, France 4ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Didcot, OX11 0QX, United Kingdom Keywords: WAAM, Solid-State Phase Transformation, Strain, Stress, Microstructure. Abstract The heating and cooling conditions during the wire arc additive manufacturing process (WAAM) generate complex thermal, metallurgical and mechanical phenomena that induce stresses and strains within the part. They are mainly due to incompatibilities between local deformations induced by thermal expansion gradients. In steels, certain phase transformations, between ferrite, austenite and martensite, can also interfere with the state of stress and strain. To reduce residual stresses and strains, we propose to control solidstate phase transformations, through local chemical composition, to drive metallurgical deformations that counter thermal distorsions. To that end, we study the various phase transformations arising from the martensitic, austenitic and ferritic stainless steels combinations. The microstructure of the 12 alloys produced in situ are analysed and related to the deformation and residual stress state, measured by neutron diffraction, to reveal their correlations. Phase evolution has been shown to have a significant influence on the stress establishment in the part, with up to 66% less strain depending on the transformations encountered. These results enable us to identify the chemical compositions for which we obtain the least deformation and stress, and therefore the microstructures to be favoured. Finally, this study paves the way for the development of functionally graded materials produced by WAAM for improved final properties.