Contents lists available at ScienceDirect Surface & Coatings Technology journal homepage: www.elsevier.com/locate/surfcoat Influence of consolidation process on functional properties of steels M. Frelek-Kozak a, ⁎ , L. Kurpaska a , E. Wyszkowska a , J. Jagielski a,b , W. Pawlak a , I. Jozwik a,b , M. Chmielewski b , K. Perkowski c , M. Lewandowska d a National Center for Nuclear Research, st. A. Sołtana 7/23, Otwock-Świerk, Poland b Institute of Electronic Materials Technology, st.Wólczynska 133, 01-919 Warsaw, Poland c Institute of Ceramics and Building Materials, Postepu 9, 02-676 Warsaw, Poland d Warsaw University of Technology, st. Wołoska 14, 00-001 Warsaw, Poland ARTICLE INFO Keywords: ODS steel Ion irradiation Mechanical properties Nanoindentation Consolidation process ABSTRACT The effects of consolidation process and low-energy ions (Ar + ) irradiation on mechanical properties of 12% Cr, 2% W, 0.25% Ti, 0.25% Y 2 O 3 (%wt.) ODS RAF steel were investigated. Three types of samples, fabricated with different methods: Spark Plasma Sintering (SPS), Hot Isostatic Pressing (HIP) and Hot Extrusion (HE) were studied. The microstructure of obtained specimens were characterized by using High Resolution Scanning Electron Microscopy (HR-SEM) and Electron Backscatter Diffraction Analysis (EBSD) techniques. Each material was submitted to low energy (160 keV) Ar + ion irradiation with fluences: 10 14 , 10 15 and 10 16 [ions/cm 2 ] what corresponds to ~4 dpa of material damage. Mechanical properties were evaluated in micro- and nano-scale, using Vickers micro-hardness HV0.1 and nanoindentation method (NI). Conducted research shows that materials manufactured by using SPS and HIP processes exhibits very similar mechanical properties, although im- plementation of the first technique provide slightly better mechanical parameters of the specimen. Moreover, conducted in different volumetric scales experiments show that similar results were obtained by different me- chanical test methods. 1. Introduction Ferritic oxide dispersion strengthening (ODS) steels are one of the most promising candidate materials for future nuclear applications. For example they are considered as structural elements of IV-gen reactors or for fusion [1–4]. Properties of these materials allows to expect that ODS steels will withstand extremely harsh environmental conditions such as: intensive radiation, high temperature, exposure for corrosive coolants, complex force fields over years or even decades of continuous service. Its uniqueness is an effect of microstructural features, such as high density of dislocation, very fine-grained microstructure and the most important – addition of nanoparticles (especially (Y-Ti-O or Y-Al-O) [3,5,6]. Presence of nano-precipitations has an indisputable ad- vantages, although these elements make fabrication process more complicated. Due to the extremely poor solubility and wettability in liquid steel of main strengthening elements - yttrium and oxygen, ODS steels are fabricated with use of mechanical alloying (MA), followed by powder metallurgy processes [7]. MA process includes mixing ele- mental powders in high energy ball mills where powder particles are repeatedly flattened, cold welded, fractured and re-welded [8]. Ob- tained powder-alloy is consolidated in the next step. One may name three main consolidation techniques which are commonly used: Spark Plasma Sintering (SPS) [9–11], Hot Isostatic Pressing (HIP) [9,12] and Hot Extrusion (HE) [11,13]. It is well-known that processing history is one of the vital factor affecting materials' properties. Materials hot extruded exhibit a morphological and crystallographic texture [14,15], whereas materials consolidated with other methods display much more random initial texture and more equiaxed morphology [12]. Moreover, consolidation process affects also a thermo-mechanical behavior of bulk material. Dadé et al. [12] have proved that material after HIP process shows strongly delayed recrystallization kinetics comparing to HE material with the same chemical composition and submitted to the same level of deformation. Despite the mentioned data, there is a lack of knowledge including the influence of consolidation method on stability of functional properties of ODS steels. For this reason, an objective of this work is to evaluate the role of consolidation process (HIP, HE and SPS) on stability of mechanical properties of ODS steel. Assessment of the mechanical changes were investigated by using nano and micro scale methods. Tested materials were exposured to the impact of ion-irradiation. This procedure is fast, safe, fully-controlled and commonly used to imitate the nuclear reactor environment [3,5,9]. https://doi.org/10.1016/j.surfcoat.2018.02.049 Received 10 October 2017; Received in revised form 7 February 2018; Accepted 13 February 2018 ⁎ Corresponding author. E-mail address: malgorzata.frelek@ncbj.gov.pl (M. Frelek-Kozak). Surface & Coatings Technology xxx (xxxx) xxx–xxx 0257-8972/ © 2018 Elsevier B.V. All rights reserved. Please cite this article as: Frelek-Kozak, M., Surface & Coatings Technology (2018), https://doi.org/10.1016/j.surfcoat.2018.02.049