Characterisation of IN718 nickle superalloy power bed fusion laser additive manufacturing

Suresh Kumar, Saikrishna (author), Klobčar, Damjan (mentor), Cao, Emmy Yu (comentor)

The proposed research investigates additively manufactured Ni-based superalloy Inconel 718 subjected to two distinct post-processing routes: ageing heat treatment and Hot Isostatic Pressing (HIP). A comprehensive characterization was carried out using optical microscopy, SEM imaging, EDS analysis, porosity quantification, grain size measurements, NbC volume fraction analysis, and Vickers hardness testing. The study aims to establish correlations between processing pathways, resulting microstructures, and their influence on mechanical performance, with particular focus on hardness and fatigue behavior. Since the fatigue reliability of LPBF-produced Inconel 718 is strongly limited by microstructural characters, the results highlight that lower porosity, moderate grain size, and a controlled NbC distribution contribute to enhanced hardness and fatigue life. Among the examined conditions, sample C3 (Heat treatment and HIP) exhibited the most favorable fatigue performance, while sample B7 (Heat treated) had the lowest fatige life.

• Language: English
• Keywords: additive manufacturing, nickel superalloy, inconel IN718, scanning electron microscopy, energy dispersive X-ray spectroscopy
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Year: 2025
• Number of pages: XV, 58 str.
• PID: 20.500.12556/RUL-175024
• UDC: 620.178.3: 543.456:669.245(043.2)
• COBISS.SI-ID: 258929667
• Publication date in RUL: 14.10.2025

Secondary language

• Language: Slovenian
• Title: Karakterizacija mikrostrukture nikljeve superzlitine INCONEL IN718 izdelane z laserskim taljenjem prahu na podlago

Abstract

Raziskava preučuje dodajalno izdelano superzlitino na osnovi niklja (Inconel 718), ki je bila podvržena dvema različnima postopkoma naknadne obdelave: izločevalnem utrjevanju in vročemu izostatičnemu stiskanju (HIP). Celovita karakterizacija je bila vključevala svetlobno mikroskopijo, SEM in EDS analizo, analizo poroznosti, meritev velikosti zrn, analizo volumskega deleža NbC in merjenje trdote po Vickersu. Namen študije je bil vzpostaviti korelacije med naknadno obdelavo, mikrostrukturami in mehanskimi lastnostnimi, s posebnim poudarkom na trdoti in odpornosti na utrujanje. Odpornost na utrujanje dodajalno izdelanega Inconela 718, izdelanega z laserskim spajanjem prahu na podlago, je močno odvisna od mikrostrukture. Rezultati kažejo, da nižja poroznost, zmerna velikost zrn in enakomerna porazdelitev NbC prispevajo k višji trdoti in odpornosti na utrujanje. Med preučevanimi pogoji je vzorec C3 (toplotno obdelan in HIP) dosegel največjo odpornost na utrujanje, vzorec B7 (toplotno obdelan) pa je imel najnižjo odpornost na utrujanje.

• Keywords: dodajalna izdelava, nikeljeva superzlitina, inconel IN718, skenirna elektronska mikroskopija (SEM), energijsko disperzna rentgenska spektroskopija (EDS)