Publicação

Dissimilar welding of CoCrFeMnNi high entropy alloy to 316 stainless steel

Detalhes bibliográficos
Resumo:	High entropy alloys have gathered recent attention due to their extraordinary mechanical properties. And with that comes the desire to couple those properties with others from different materials, through dissimilar welding. In this work, gas tungsten arc welding is used to fuse together a CoCrFeMnNi high entropy alloy to a commercially available 316 stainless steel. The objective is to try to add the former's high fracture toughness and ductility to the latter's excellent corrosion resistance and see if it can be employed in structural-oriented applications. Two different samples were made to compare the influ- ence of post-weld heat treatments on the microstructure and mechanical properties. The microstructure study and evaluation were done resorting to optical and electron microscopy and X-ray diffraction. The mechanical properties were determined using a microdurometer and tensile testing. The microstructure was then assessed and correlated with the results of the mechanical tests. The results show a significant difference in hardness throughout the welded joints. The as-rolled sample shows a decrease of about 200 HV between the CoCrFeMnNi and the 316 stainless steel with a hardness value of about 150 HV in the fusion zone. The as-annealed sample maintains a constant HV value throughout the welded joint, of around 160 to 170 HV. This is coherent with the electron microscopy observations and may be a result of a new solid solution forming in the fusion zone. The tensile tests show both samples fractured at the fusion zone. This difference in ductility and hardness can be explained by the increase in grain size and stress relief from the annealing.
Autores principais:	Mestre, Martim Francisco Palma
Assunto:	High Entropy Alloy tainless Steel Dissimilar Welding Gas Tungsten Arc Welding Annealing Mechanical Properties
Ano:	2023
País:	Portugal
Tipo de documento:	dissertação de mestrado
Tipo de acesso:	acesso aberto
Instituição associada:	Universidade Nova de Lisboa
Idioma:	inglês
Origem:	Repositório Institucional da UNL

Descrição
Resumo:	High entropy alloys have gathered recent attention due to their extraordinary mechanical properties. And with that comes the desire to couple those properties with others from different materials, through dissimilar welding. In this work, gas tungsten arc welding is used to fuse together a CoCrFeMnNi high entropy alloy to a commercially available 316 stainless steel. The objective is to try to add the former's high fracture toughness and ductility to the latter's excellent corrosion resistance and see if it can be employed in structural-oriented applications. Two different samples were made to compare the influ- ence of post-weld heat treatments on the microstructure and mechanical properties. The microstructure study and evaluation were done resorting to optical and electron microscopy and X-ray diffraction. The mechanical properties were determined using a microdurometer and tensile testing. The microstructure was then assessed and correlated with the results of the mechanical tests. The results show a significant difference in hardness throughout the welded joints. The as-rolled sample shows a decrease of about 200 HV between the CoCrFeMnNi and the 316 stainless steel with a hardness value of about 150 HV in the fusion zone. The as-annealed sample maintains a constant HV value throughout the welded joint, of around 160 to 170 HV. This is coherent with the electron microscopy observations and may be a result of a new solid solution forming in the fusion zone. The tensile tests show both samples fractured at the fusion zone. This difference in ductility and hardness can be explained by the increase in grain size and stress relief from the annealing.