High-temperature Fatigue and Creep Performance of Additively Manufactured NiCu-based Alloy

Abstract

NiCu-based alloys are frequently employed as a key material for heat exchangers and superheated steam systems where the emphasis is put on the resistance against metal dusting and corrosion in harsh environments and, at the same time, excellent mechanical properties at elevated temperatures. The present contribution delivers the experimental results on high-temperature fatigue and creep performance of additively manufactured NiCu-based Alloy 400 and compares it with conventionally produced material. The fatigue tests were performed in symmetrical force control loading in laboratory air at elevated temperatures. Standard constant stress uniaxial creep tests were carried out up to the rupture at applied stresses ranging from 30 to 150 MPa and temperatures between 600–880°C in a protective argon atmosphere. Results indicate inferior fatigue and creep properties of additively manufactured Alloy 400. This detrimental effect of the manufacturing process on mechanical properties can be caused by several factors, including the orientation of the building direction relative to the loading direction, strong texture in 〈011〉 direction, and also by the presence of defects revealed by means of scanning electron microscopy on fracture surfaces of additively manufactured materials.