Steel

Nanostructure Characterisation of Flow Formed Cr-Mo-V Steel using Transmission Kikuchi Diffraction Technique

Nowadays flow-forming has become a desired near net shape manufacturing method as it provides excellent mechanical properties with improved surface finish and significant manufacturing cost reduction. However, the material is subjected to excessive plastic deformation during flow-forming process, generating a very fine and complex microstructure. In addition, the intense dislocation density and residual stress that is generated in the component during processing makes the microstructure … Continue reading Nanostructure Characterisation of Flow Formed Cr-Mo-V Steel using Transmission Kikuchi Diffraction Technique

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Nickel, Small Punch, Superalloys

Deformation mechanisms of IN713C nickel based superalloy during Small Punch Testing

The role of local microstructure is critical in materials performance and integrity in a cast alloy. The grain size and grain boundary distributions as well as local texture can create various microstructure/microtexture clusters that cause deformation localisation in the alloy. Inconel 713C nickel base superalloys are used as turbocharger turbine wheels for modern diesel engines, produced via investment casting. In such an alloy localised deformation … Continue reading Deformation mechanisms of IN713C nickel based superalloy during Small Punch Testing

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Nickel, Superalloys

The effect of strain distribution on microstructural developments during forging in a newly developed nickel base superalloy

In the current study, the effect of strain distribution in a simple forging geometry on the propensity for recrystallization, and its impact on mechanical properties has been investigated in a newly developed experimental nickel-based superalloy. The new alloy was produced via a Powder Metallurgy (PM) route and was subsequently Hot Isostatic Processed (HIP), isothermally forged, and heat treated to produce a coarse grain microstructure with … Continue reading The effect of strain distribution on microstructural developments during forging in a newly developed nickel base superalloy

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Tensile, Titanium

The hierarchy of microstructure parameters affecting the tensile ductility in centrifugally cast and forged Ti-834 alloy during high temperature exposure in air

Ductility regression is the main concern in using Ti-834 titanium alloy at temperatures above 500 °C for aerospace applications. The reduction of ductility in titanium alloys at high temperatures is strongly correlated to the exposure time. In the current study the effect of prolonged exposure at 500 °C on the tensile ductility of two differently processed Ti-834 alloys was investigated. In order to simulate actual … Continue reading The hierarchy of microstructure parameters affecting the tensile ductility in centrifugally cast and forged Ti-834 alloy during high temperature exposure in air

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Creep, Fatigue

Computational modeling of creep-based fatigue as a means of selecting lead-free solder alloys

The primary aim of this investigation was to understand the effect of temperature fluctuations on a number of various solder materials namely SAC105, SAC305, SAC405 and Sn–36Pb–2Ag. To achieve this objective, three different classic joint assemblies (a ball joint, a test specimen joint and finger lead joint) were modeled which provided the foundation for the creep and fatigue behaviors simulation. Anand’s viscoplasticity as a constitutive … Continue reading Computational modeling of creep-based fatigue as a means of selecting lead-free solder alloys

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Steel

Investigation into the effect of process parameters on microstructural and physical properties of 316L stainless steel parts by selective laser melting

Additive manufacturing by selective laser melting (SLM) was used to investigate the effect of laser energy density on 316L stainless steel properties. Point distance and exposure time were varied and their impact on porosity, surface finish, microstructure, density and hardness, was evaluated. The surface roughness was primarily affected by point distance with increased point distance resulting in increased surface roughness, R a, from 10 to … Continue reading Investigation into the effect of process parameters on microstructural and physical properties of 316L stainless steel parts by selective laser melting

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Environmental

Establishing a quantifiable tarnish timeline for comparison of anti-tarnish processes in metals

Brass samples were controllably tarnished using the thioacetamide accelerated corrosion (ISO 4538:1995) and synthetic sweat (ISO 3160–2:2003) methods. Spectrophotometry, energy dispersive X-ray spectroscopy (EDX) and electrochemical impedance spectroscopy (EIS) were performed on samples tarnished for set exposure times over seven days. Synthetic sweat produced a loose surface corrosion layer, which limited the use of EIS and spectrophotometry, but for the thioacetamide method both measurements produced … Continue reading Establishing a quantifiable tarnish timeline for comparison of anti-tarnish processes in metals

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Environmental, Nickel, Superalloys

Localized microstructural characterization of a dissimilar metal electron beam weld joint from an aerospace component

Hydrogen induced cold cracking (HICC) and hydrogen embrittlement (HE) are influenced by the microstructural evolution, residual plastic strain (i.e. local misorientation), recrystallization of grains and the resultant grain boundary characteristic distribution (GBCD) brought about by welding processes. HICC and HE are known to cause failures in aerospace components and it is vitally important to quantify the microstructural evolution, degree of residual plastic strain and determine … Continue reading Localized microstructural characterization of a dissimilar metal electron beam weld joint from an aerospace component

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Creep, Steel

Constraints Imposed by the Wilshire Methodology on Creep Rupture Data and Procedures for Testing the Validity of Such Constraints: Illustration Using 1Cr-1Mo-0.25V Steel

A new parametric approach, termed the Wilshire equations, offers the realistic potential of being able to accurately life materials operating at in service conditions from accelerated test results lasting no more than 5000 hours. These Wilshire equations contain discontinuities that have in the literature been interpreted either in terms of changing deformation mechanisms or changes in where deformation occurs within a material (i.e., within boundaries or … Continue reading Constraints Imposed by the Wilshire Methodology on Creep Rupture Data and Procedures for Testing the Validity of Such Constraints: Illustration Using 1Cr-1Mo-0.25V Steel

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Creep, Steel

The importance of creep strain in linking together the Wilshire equations for minimum creep rates and times to various strains (including the rupture strain): An illustration using 1Cr-Mo-V rotor steel

This paper highlights the observation that the Wilshire equations for failure times and times to various strains, as reported in the original literature, may not be the most appropriate ones for all materials—including the one selected in this study. Further, such appropriateness can be determined by looking at the consistencies between the parameter estimates obtained using minimum creep rates in comparison to using failure times. … Continue reading The importance of creep strain in linking together the Wilshire equations for minimum creep rates and times to various strains (including the rupture strain): An illustration using 1Cr-Mo-V rotor steel

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