Industries that rely on additive manufacturing of metallic parts, especially biomedical companies, require material science-based knowledge of how process parameters and methods affect the properties ...of manufactured elements, but such phenomena are incompletely understood. In this study, we investigated the influence of selective laser melting (SLM) process parameters and additional heat treatment on mechanical properties. The research included structural analysis of residual stress, microstructure, and scleronomic hardness in low-depth measurements. Tensile tests with specimen deformation analysis using digital image correlation (DIC) were performed as well. Experiment results showed it was possible to observe the porosity growth mechanism and its influence on the material strength. Specimens manufactured with 20% lower energy density had almost half the elongation, which was directly connected with the porosity growth during energy density reduction. Hot isostatic pressing (HIP) treatment allowed for a significant reduction of porosity and helped achieve properties similar to specimens manufactured using different levels of energy density.
•W-1%TiC powder was mechanically alloyed using the stainless steel milling system.•Two-step HIPping process of the powder was applied.•Up to 1200°C (1473K), thermal expansion parameters of two-step ...HIPped W-1%TiC alloy exhibits thermally unchanged values, comparable with a pure W rod.•To increase the relative density of the W-TiC alloy, the temperature of the first-step HIPping should be ∼1300°C (1573K) and higher.
In this work an influence of a fabrication route on the microstructure, thermal and mechanical properties of the W-1%TiC was studied. The W-1%TiC powder was mechanically alloyed using the stainless steel milling media. Two-step HIPping of the powder at 1300°C (1573K) and then at 1750°C (2023K) was performed. After second-step HIPping, in spite of 13.5% of porosity, bending stress and strain values were 300MPa and 2%, respectively. On the contrary, the grain growth (from 0.7 up to 22.0μm) and coarsening mechanisms of the TiC nanoparticles were observed. Up to 1200°C (1473K), thermal expansion parameters of two-step HIPped W-1%TiC alloy exhibited thermally unchanged values, comparable with a pure W rod, however, the thermal conductivity of the W-TiC alloy at RT was 26.5W/mK, and at 1200°C (1473K) this parameter increased up to 44.8W/mKmK.
The effects of consolidation process and low-energy ions (Ar+) irradiation on mechanical properties of 12% Cr, 2% W, 0.25% Ti, 0.25% Y2O3 (%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: 1014, 1015 and 1016 ions/cm2 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 implementation 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 mechanical test methods.
•Three ODS steel were consolidated with different methods: SPS, HIP and HE•Samples were submitted to low-energy Ar+ ion irradiation•Mechanical properties of virgin and after ion-irradiation materials were investigated•Significant change of mechanical parameters has been observed
•The HIPping parameters of the 14Cr–2W–0.3Ti–0.3Y2O3 ODS steel powder were investigated.•The density and microstructure of the tested specimens after HIPping were studied.•The mechanical properties, ...high temperature tensile tests, were performed.•Residual porosity was observed in all tested specimens.•HIPping pressure has negligible influence on the strength of the ODS steel however improves material ductility.
An oxide dispersion strengthened ferritic steel with a nominal composition of Fe–14Cr–2W–0.3Ti–0.3Y2O3 (in wt.%) was consolidated by hot isostatic pressing at 1150°C under various pressures in the range of 185–300MPa for 3h. The microstructure, microhardness and high temperature tensile properties of the steel were investigated. With increasing compaction pressure the density of specimens also increased, however OM and SEM observations revealed residual porosity in all tested specimens and similar ferritic microstructure with bimodal-like grains and numerous of large oxide particles, located at the grain boundaries. Mechanical testing revealed that compaction pressure has negligible influence on the hardness and tensile strength of the ODS steel, however improves the material ductility.
The work presents results of solution combustion method utilization for yttria (Y2O3) nanopowder fabrication. Experiments were carried out with four different reducing agents: urea, glycine, citric ...acid and malonic acid added in stoichiometric ratio. The reactions were investigated using simultaneous DSC/DTA thermal analysis. After synthesis the reaction products were calcined at temperature range of 800-1100°C and analyzed in terms of particle size, specific surface area and morphology. Best results were obtained for nanoyttria powder produced from glycine. After calcination at temperature of 1100°C the powder exhibits in a form of nanometric, globular particles of diameter <100 nm, according to SEM analysis. The dBET for thus obtained powder is 104 nm, however the powder is agglomerated as the particle size measured by dynamic light scattering analysis is 1190 nm (dV50).
In this study, mechanical properties of two ODS steels, characterized by the same chemical composition yet manufactured by using two different production methods, namely High Isostatic Pressure (HIP) ...and Hot Extrusion (HE), have been investigated at high temperature by nanoindentation technique. The hardness of the material was evaluated from room temperature up to 600 °C, while initial creep behavior was estimated at room temperature and at 600 °C. In order to better understand the mechanical response of the materials, especially impact of the surface effects, mechanical maps (hardness and reduced young modulus) have been created.
